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• Determining cause of high NFS/IO utilization without iotop

  - by Matt

  I have a server that is doing an NFSv4 export for user's home directories. There are roughly 25 users (mostly developers/analysts) and about 40 servers mounting the home directory export. Performance is miserable, with users often seeing multi-second lags for simple commands (like ls, or writing a small text file). Sometimes the home directory mount completely hangs for minutes, with users getting "permission denied" errors. The hardware is a Dell R510 with dual E5620 CPUs and 8 GB RAM. There are eight 15k 2.5” 600 GB drives (Seagate ST3600057SS) configured in hardware RAID-6 with a single hot spare. RAID controller is a Dell PERC H700 w/512MB cache (Linux sees this as a LSI MegaSAS 9260). OS is CentOS 5.6, home directory partition is ext3, with options “rw,data=journal,usrquota”. I have the HW RAID configured to present two virtual disks to the OS: /dev/sda for the OS (boot, root and swap partitions), and /dev/sdb for the home directories. What I find curious, and suspicious, is that the sda device often has very high utilization, even though it only contains the OS. I would expect this virtual drive to be idle almost all the time. The system is not swapping, according to "free" and "vmstat". Why would there be major load on this device? Here is a 30-second snapshot from iostat: Time: 09:37:28 AM Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sda 0.00 44.09 0.03 107.76 0.13 607.40 11.27 0.89 8.27 7.27 78.35 sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sda2 0.00 44.09 0.03 107.76 0.13 607.40 11.27 0.89 8.27 7.27 78.35 sdb 0.00 2616.53 0.67 157.88 2.80 11098.83 140.04 8.57 54.08 4.21 66.68 sdb1 0.00 2616.53 0.67 157.88 2.80 11098.83 140.04 8.57 54.08 4.21 66.68 dm-0 0.00 0.00 0.03 151.82 0.13 607.26 8.00 1.25 8.23 5.16 78.35 dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 dm-2 0.00 0.00 0.67 2774.84 2.80 11099.37 8.00 474.30 170.89 0.24 66.84 dm-3 0.00 0.00 0.67 2774.84 2.80 11099.37 8.00 474.30 170.89 0.24 66.84 Looks like iotop is the ideal tool to use to sniff out these kinds of issues. But I'm on CentOS 5.6, which doesn't have a new enough kernel to support that program. I looked at Determining which process is causing heavy disk I/O?, and besides iotop, one of the suggestions said to do a "echo 1 /proc/sys/vm/block_dump". I did that (after directing kernel messages to tempfs). In about 13 minutes I had about 700k reads or writes, roughly half from kjournald and the other half from nfsd: # egrep " kernel: .*(READ|WRITE)" messages | wc -l 768439 # egrep " kernel: kjournald.*(READ|WRITE)" messages | wc -l 403615 # egrep " kernel: nfsd.*(READ|WRITE)" messages | wc -l 314028 For what it's worth, for the last hour, utilization has constantly been over 90% for the home directory drive. My 30-second iostat keeps showing output like this: Time: 09:36:30 PM Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sda 0.00 6.46 0.20 11.33 0.80 71.71 12.58 0.24 20.53 14.37 16.56 sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sda2 0.00 6.46 0.20 11.33 0.80 71.71 12.58 0.24 20.53 14.37 16.56 sdb 137.29 7.00 549.92 3.80 22817.19 43.19 82.57 3.02 5.45 1.74 96.32 sdb1 137.29 7.00 549.92 3.80 22817.19 43.19 82.57 3.02 5.45 1.74 96.32 dm-0 0.00 0.00 0.20 17.76 0.80 71.04 8.00 0.38 21.21 9.22 16.57 dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 dm-2 0.00 0.00 687.47 10.80 22817.19 43.19 65.48 4.62 6.61 1.43 99.81 dm-3 0.00 0.00 687.47 10.80 22817.19 43.19 65.48 4.62 6.61 1.43 99.82

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• No device file for partition on logical volume (Linux LVM)

  - by Brian

  I created a logical volume (scandata) containing a single ext3 partition. It is the only logical volume in its volume group (case4t). Said volume group is comprised by 3 physical volumes, which are three primary partitions on a single block device (/dev/sdb). When I created it, I could mount the partition via the block device /dev/mapper/case4t-scandatap1. Since last reboot the aforementioned block device file has disappeared. It may be of note -- I'm not sure -- that my superior (a college professor) had prompted this reboot by running sudo chmod -R [his name] /usr/bin, which obliterated all suid in its path, preventing the both of us from sudo-ing. That issue has been (temporarily) rectified via this operation. Now I'll cut the chatter and get started with the terminal dumps: $ sudo pvs; sudo vgs; sudo lvs Logging initialised at Sat Jan 8 11:42:34 2011 Set umask to 0077 Scanning for physical volume names PV VG Fmt Attr PSize PFree /dev/sdb1 case4t lvm2 a- 819.32G 0 /dev/sdb2 case4t lvm2 a- 866.40G 0 /dev/sdb3 case4t lvm2 a- 47.09G 0 Wiping internal VG cache Logging initialised at Sat Jan 8 11:42:34 2011 Set umask to 0077 Finding all volume groups Finding volume group "case4t" VG #PV #LV #SN Attr VSize VFree case4t 3 1 0 wz--n- 1.69T 0 Wiping internal VG cache Logging initialised at Sat Jan 8 11:42:34 2011 Set umask to 0077 Finding all logical volumes LV VG Attr LSize Origin Snap% Move Log Copy% Convert scandata case4t -wi-a- 1.69T Wiping internal VG cache $ sudo vgchange -a y Logging initialised at Sat Jan 8 11:43:14 2011 Set umask to 0077 Finding all volume groups Finding volume group "case4t" 1 logical volume(s) in volume group "case4t" already active 1 existing logical volume(s) in volume group "case4t" monitored Found volume group "case4t" Activated logical volumes in volume group "case4t" 1 logical volume(s) in volume group "case4t" now active Wiping internal VG cache $ ls /dev | grep case4t case4t $ ls /dev/mapper case4t-scandata control $ sudo fdisk -l /dev/case4t/scandata Disk /dev/case4t/scandata: 1860.5 GB, 1860584865792 bytes 255 heads, 63 sectors/track, 226203 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x00049bf5 Device Boot Start End Blocks Id System /dev/case4t/scandata1 1 226203 1816975566 83 Linux $ sudo parted /dev/case4t/scandata print Model: Linux device-mapper (linear) (dm) Disk /dev/mapper/case4t-scandata: 1861GB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 32.3kB 1861GB 1861GB primary ext3 $ sudo fdisk -l /dev/sdb Disk /dev/sdb: 1860.5 GB, 1860593254400 bytes 255 heads, 63 sectors/track, 226204 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x00000081 Device Boot Start End Blocks Id System /dev/sdb1 1 106955 859116006 83 Linux /dev/sdb2 113103 226204 908491815 83 Linux /dev/sdb3 106956 113102 49375777+ 83 Linux Partition table entries are not in disk order $ sudo parted /dev/sdb print Model: DELL PERC 6/i (scsi) Disk /dev/sdb: 1861GB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 32.3kB 880GB 880GB primary reiserfs 3 880GB 930GB 50.6GB primary 2 930GB 1861GB 930GB primary I find it a bit strange that partition one above is said to be reiserfs, or if it matters -- it was previously reiserfs, but LVM recognizes it as a PV. To reiterate, neither /dev/mapper/case4t-scandatap1 (which I had used previously) nor /dev/case4t/scandata1 (as printed by fdisk) exists. And /dev/case4t/scandata (no partition number) cannot be mounted: $sudo mount -t ext3 /dev/case4t/scandata /mnt/new mount: wrong fs type, bad option, bad superblock on /dev/mapper/case4t-scandata, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so All I get on syslog is: [170059.538137] VFS: Can't find ext3 filesystem on dev dm-0. Thanks in advance for any help you can offer, Brian P.S. I am on Ubuntu GNU/Linux 2.6.28-11-server (Jaunty) (out of date, I know -- that's on the laundry list).

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• reiserfsck on lvm

  - by DaDaDom

  It seems like my filesystem got corrupted somehow during the last reboot of my server. I can't fsck some logical volumes anymore. The setup: root@rescue ~ # cat /mnt/rescue/etc/fstab proc /proc proc defaults 0 0 /dev/md0 /boot ext3 defaults 0 2 /dev/md1 / ext3 defaults,errors=remount-ro 0 1 /dev/systemlvm/home /home reiserfs defaults 0 0 /dev/systemlvm/usr /usr reiserfs defaults 0 0 /dev/systemlvm/var /var reiserfs defaults 0 0 /dev/systemlvm/tmp /tmp reiserfs noexec,nosuid 0 2 /dev/sda5 none swap defaults,pri=1 0 0 /dev/sdb5 none swap defaults,pri=1 0 0 [UPDATE] First question: what "part" should I check for bad blocks? The logical volume, the underlying /dev/md or the /dev/sdx below that? Is doing what I am doing the right way to go? [/UPDATE] The errormessage when checking /dev/systemlvm/usr: root@rescue ~ # reiserfsck /dev/systemlvm/usr reiserfsck 3.6.19 (2003 www.namesys.com) [...] Will read-only check consistency of the filesystem on /dev/systemlvm/usr Will put log info to 'stdout' Do you want to run this program?[N/Yes] (note need to type Yes if you do):Yes ########### reiserfsck --check started at Wed Feb 3 07:10:55 2010 ########### Replaying journal.. Reiserfs journal '/dev/systemlvm/usr' in blocks [18..8211]: 0 transactions replayed Checking internal tree.. Bad root block 0. (--rebuild-tree did not complete) Aborted Well so far, let's try --rebuild-tree: root@rescue ~ # reiserfsck --rebuild-tree /dev/systemlvm/usr reiserfsck 3.6.19 (2003 www.namesys.com) [...] Will rebuild the filesystem (/dev/systemlvm/usr) tree Will put log info to 'stdout' Do you want to run this program?[N/Yes] (note need to type Yes if you do):Yes Replaying journal.. Reiserfs journal '/dev/systemlvm/usr' in blocks [18..8211]: 0 transactions replayed ########### reiserfsck --rebuild-tree started at Wed Feb 3 07:12:27 2010 ########### Pass 0: ####### Pass 0 ####### Loading on-disk bitmap .. ok, 269716 blocks marked used Skipping 8250 blocks (super block, journal, bitmaps) 261466 blocks will be read 0%....20%....40%....60%....80%....100% left 0, 11368 /sec 52919 directory entries were hashed with "r5" hash. "r5" hash is selected Flushing..finished Read blocks (but not data blocks) 261466 Leaves among those 13086 Objectids found 53697 Pass 1 (will try to insert 13086 leaves): ####### Pass 1 ####### Looking for allocable blocks .. finished 0% left 12675, 0 /sec The problem has occurred looks like a hardware problem (perhaps memory). Send us the bug report only if the second run dies at the same place with the same block number. mark_block_used: (39508) used already Aborted Bad. But let's do it again as mentioned: [...] Flushing..finished Read blocks (but not data blocks) 261466 Leaves among those 13085 Objectids found 54305 Pass 1 (will try to insert 13085 leaves): ####### Pass 1 ####### Looking for allocable blocks .. finished 0%... left 12127, 958 /sec The problem has occurred looks like a hardware problem (perhaps memory). Send us the bug report only if the second run dies at the same place with the same block number. build_the_tree: Nothing but leaves are expected. Block 196736 - internal Aborted Same happens every time, only the actual error message changes. Sometimes I get mark_block_used: (somenumber) used already, other times the block number changes. Seems like something is REALLY broken. Are there any chances I can somehow get the partitions to work again? It's a server to which I don't have physical access directly (hosted server). Thanks in advance!

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• Moving users folder on Windows-7 to another partition - bad idea?

  - by Donat

  Hi, I'd like to re-submit here a question posted by Benjol on Aug 17at 5:57 "Moving users folder on Windows Vista to another partition - bad idea?" (I can't post one than one link until I earn "10 reputation" and removed my "answer" there to post my follow-up questions here). I am anxiously getting ready at long last to to carry out a clean install (using custom install option) from Vista to Windows-7 Home Premium 64bit with the free upgrade I received late October. For my Vista system I successfully set-up last Summer a multi-partitions scheme with Users and Program Data on a a different partition than the operating system (see link below, and its subsequent links in my comment for details). http://tuts4tech.net/2009/08/05/windows-7-move-the-users-and-program-files-directories-to-a-different-partition/comment-page-1/#comment-562 I was planning a similar set-up for windows 7, a little more streamlined, with OS, Program Files on C:, Users and Program Data on D:, and TV media recording on a separate partition. Reading the Question submitted by Benjol, I am second guessing too. Is moving Users and Program Data on a different partition than the default primary partition with OS and Program Files such a good idea? The couple of people I talked to at the official Microsoft Windows 7 booth at CES 2010 gave the same answer to the intention of moving the Users profile folder to another partition. In a nutshell, they all told me that they used to do this in XP and less in Vista but not anymore with Windows 7... "It is stable, after two months still no problem" I had the feeling it was a scripted answer to emphasize how Windows 7 is so stable and efficient... (Will Windows-7 system not become bugged down over the course of several months to a year or two? Only time will tell) Long story short, I share the same view than Benjol expressed with respect to being "able to backup and restore system and user data independently." I just received a 2TB usb2, eSATA external hard drive as a back-up drive, which includes NTI Shadow 4 (4.1.0.150) for back-up solution. I took note of the issue with NTUSER.DAT and I will read more about Volume Shadow Copy Service (VSS) for Windows 7. I am willing to put the effort if placing Users and Program Data on a different partition would allow to restore a fresher OS+Program image when the system gets bugged down. Questions: Is it such a bad idea? What is the "easy route" referred by Benjol in his post? Is it to just relocate folders to another partition using the Folder property tool? (It is not practical for several users and might not provide a straightforward restore process of just OS and Program Files when needed.) I am starting to learn about Windows 7 libraries. Would Windows 7 libraries be another alternative to achieve this? All this reading to decide how to organize the partition scheme for my custom system is starting to be confusing. I apologize for this lengthy Question. It is my first day here on SuperUser and I am just learning how different from a discussion thread it is. Thank you in advance for all your suggestions and comments. Donat

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• RHCS: GFS2 in A/A cluster with common storage. Configuring GFS with rgmanager

  - by Pavel A

  I'm configuring a two node A/A cluster with a common storage attached via iSCSI, which uses GFS2 on top of clustered LVM. So far I have prepared a simple configuration, but am not sure which is the right way to configure gfs resource. Here is the rm section of /etc/cluster/cluster.conf: <rm> <failoverdomains> <failoverdomain name="node1" nofailback="0" ordered="0" restricted="1"> <failoverdomainnode name="rhc-n1"/> </failoverdomain> <failoverdomain name="node2" nofailback="0" ordered="0" restricted="1"> <failoverdomainnode name="rhc-n2"/> </failoverdomain> </failoverdomains> <resources> <script file="/etc/init.d/clvm" name="clvmd"/> <clusterfs name="gfs" fstype="gfs2" mountpoint="/mnt/gfs" device="/dev/vg-cs/lv-gfs"/> </resources> <service name="shared-storage-inst1" autostart="0" domain="node1" exclusive="0" recovery="restart"> <script ref="clvmd"> <clusterfs ref="gfs"/> </script> </service> <service name="shared-storage-inst2" autostart="0" domain="node2" exclusive="0" recovery="restart"> <script ref="clvmd"> <clusterfs ref="gfs"/> </script> </service> </rm> This is what I mean: when using clusterfs resource agent to handle GFS partition, it is not unmounted by default (unless force_unmount option is given). This way when I issue clusvcadm -s shared-storage-inst1 clvm is stopped, but GFS is not unmounted, so a node cannot alter LVM structure on shared storage anymore, but can still access data. And even though a node can do it quite safely (dlm is still running), this seems to be rather inappropriate to me, since clustat reports that the service on a particular node is stopped. Moreover if I later try to stop cman on that node, it will find a dlm locking, produced by GFS, and fail to stop. I could have simply added force_unmount="1", but I would like to know what is the reason behind the default behavior. Why is it not unmounted? Most of the examples out there silently use force_unmount="0", some don't, but none of them give any clue on how the decision was made. Apart from that I have found sample configurations, where people manage GFS partitions with gfs2 init script - https://alteeve.ca/w/2-Node_Red_Hat_KVM_Cluster_Tutorial#Defining_The_Resources or even as simply as just enabling services such as clvm and gfs2 to start automatically at boot (http://pbraun.nethence.com/doc/filesystems/gfs2.html), like: chkconfig gfs2 on If I understand the latest approach correctly, such cluster only controls whether nodes are still alive and can fence errant ones, but such cluster has no control over the status of its resources. I have some experience with Pacemaker and I'm used to that all resources are controlled by a cluster and an action can be taken when not only there are connectivity issues, but any of the resources misbehave. So, which is the right way for me to go: leave GFS partition mounted (any reasons to do so?) set force_unmount="1". Won't this break anything? Why this is not the default? use script resource <script file="/etc/init.d/gfs2" name="gfs"/> to manage GFS partition. start it at boot and don't include in cluster.conf (any reasons to do so?) This may be a sort of question that cannot be answered unambiguously, so it would be also of much value for me if you shared your experience or expressed your thoughts on the issue. How does for example /etc/cluster/cluster.conf look like when configuring gfs with Conga or ccs (they are not available to me since for now I have to use Ubuntu for the cluster)? Thanks you very much!

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• md/raid:md2: cannot start dirty degraded array, kernel panic

  - by nl-x

  After having made use of a remote power switch, my server did not come back online. When I went to the datacenter and reboot the computer on the spot I see the server booting (I see the centos progress bar with running almost all the way to the end) and eventually giving the following messages: md/raid:md2: cannot start dirty degraded array. md/raid:md2: failed to run raid set. md: pers->run() failed ... md/raid:md2: cannot start dirty degraded array. md/raid:md2: failed to run raid set. md: pers->run() failed ... Kernel panic - not syncing: Attempted to kill init! Pid: 1, comm: init not tainted 2.6.32-279.1.1.el6.i686 #1 Call Trace: [<c083bfbc>] ? panic+0x68/0x11c [<c045a501>] ? do_exit+0x741/0x750 [<c045a54c>] ? do_group_exit+0x3c/0xa0 [<c045a5c1>] ? sys_exit_group+0x11/0x20 [<c083eba4>] ? syscall_call+0x7/0xb [<c083007b>] ? cmos_wake_setup+0x62/0x112 The server runs CentOS and has software raid, and I don't have backups of the raid settings. The only backup I have is of /home and the database dumps. (Glad to at least have those though.) Since the server is an old Dell PowerEdge 1750 with no CD-ROM drive, I have no way of booting the machine from a boot disk. I also remember in the past that the server also wouldn't boot from a bootable USB disk. So the only way I know how to boot the server is to go to the datacenter, pick up the server and take it to the office. Screw open the server. Attach a cdrom drive to an IDE slot on the motherboard. And then boot it. I am hoping you guys could help me avoid this. I have looked a bit through the boot options and I found the following boot options. When CentOS is about to boot and interrupt the boot-countdown: CentOS (2.6.32-279.1.1.el63.i686) CentOS Linux (2.6.32-71.29.1.el6.i686) centos (2.6.32-71.el6.i686) I think the first configuration is the default one, because choosing that gets me to the above mentioned kernel panic. The other ones end with something like "Sleeping forever". I can press 'e' to edit boot commands, press 'a' to modify kernel arguments and press 'c' for grub command line. The command line gives a grub prompt. But I have no idea how to get the system to boot without (trying to) access the dirty partitions. What I want to do is off course: - boot the machine - check hard drive for errors - mark the drive as clean

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• volume group disappeared after xfs_check run

  - by John P

  EDIT** I have a volume group consisting of 5 RAID1 devices grouped together into a lvm and formatted with xfs. The 5th RAID device lost its RAID config (cat /proc/mdstat does not show anything). The two drives are still present (sdj and sdk), but they have no partitions. The LVM appeared to be happily using sdj up until recently. (doing a pvscan showed the first 4 RAID1 devices + /dev/sdj) I removed the LVM from the fstab, rebooted, then ran xfs_check on the LV. It ran for about half an hour, then stopped with an error. I tried rebooting again, and this time when it came up, the logical volume was no longer there. It is now looking for /dev/md5, which is gone (though it had been using /dev/sdj earlier). /dev/sdj was having read errors, but after replacing the SATA cable, those went away, so the drive appears to be fine for now. Can I modify the /etc/lvm/backup/dedvol, change the device to /dev/sdj and do a vgcfgrestore? I could try doing a pvcreate --uuid KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ /dev/sdj to make it recognize it, but I'm afraid that would erase the data on the drive UPDATE: just changing the pv to point to /dev/sdj did not work vgcfgrestore --file /etc/lvm/backup/dedvol dedvol Couldn't find device with uuid 'KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ'. Cannot restore Volume Group dedvol with 1 PVs marked as missing. Restore failed. pvscan /dev/sdj: read failed after 0 of 4096 at 0: Input/output error Couldn't find device with uuid 'KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ'. Couldn't find device with uuid 'KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ'. Couldn't find device with uuid 'KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ'. Couldn't find device with uuid 'KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ'. PV /dev/sdd2 VG VolGroup00 lvm2 [74.41 GB / 0 free] PV /dev/md2 VG dedvol lvm2 [931.51 GB / 0 free] PV /dev/md3 VG dedvol lvm2 [931.51 GB / 0 free] PV /dev/md0 VG dedvol lvm2 [931.51 GB / 0 free] PV /dev/md4 VG dedvol lvm2 [931.51 GB / 0 free] PV unknown device VG dedvol lvm2 [1.82 TB / 63.05 GB free] Total: 6 [5.53 TB] / in use: 6 [5.53 TB] / in no VG: 0 [0 ] vgscan Reading all physical volumes. This may take a while... /dev/sdj: read failed after 0 of 4096 at 0: Input/output error /dev/sdj: read failed after 0 of 4096 at 2000398843904: Input/output error Found volume group "VolGroup00" using metadata type lvm2 Found volume group "dedvol" using metadata type lvm2 vgdisplay dedvol --- Volume group --- VG Name dedvol System ID Format lvm2 Metadata Areas 5 Metadata Sequence No 10 VG Access read/write VG Status resizable MAX LV 0 Cur LV 1 Open LV 0 Max PV 0 Cur PV 5 Act PV 5 VG Size 5.46 TB PE Size 4.00 MB Total PE 1430796 Alloc PE / Size 1414656 / 5.40 TB Free PE / Size 16140 / 63.05 GB VG UUID o1U6Ll-5WH8-Pv7Z-Rtc4-1qYp-oiWA-cPD246 dedvol { id = "o1U6Ll-5WH8-Pv7Z-Rtc4-1qYp-oiWA-cPD246" seqno = 10 status = ["RESIZEABLE", "READ", "WRITE"] flags = [] extent_size = 8192 # 4 Megabytes max_lv = 0 max_pv = 0 physical_volumes { pv0 { id = "Msiee7-Zovu-VSJ3-Y2hR-uBVd-6PaT-Ho9v95" device = "/dev/md2" # Hint only status = ["ALLOCATABLE"] flags = [] dev_size = 1953519872 # 931.511 Gigabytes pe_start = 384 pe_count = 238466 # 931.508 Gigabytes } pv1 { id = "ZittCN-0x6L-cOsW-v1v4-atVN-fEWF-e3lqUe" device = "/dev/md3" # Hint only status = ["ALLOCATABLE"] flags = [] dev_size = 1953519872 # 931.511 Gigabytes pe_start = 384 pe_count = 238466 # 931.508 Gigabytes } pv2 { id = "NRNo0w-kgGr-dUxA-mWnl-bU5v-Wld0-XeKVLD" device = "/dev/md0" # Hint only status = ["ALLOCATABLE"] flags = [] dev_size = 1953519872 # 931.511 Gigabytes pe_start = 384 pe_count = 238466 # 931.508 Gigabytes } pv3 { id = "2EfLFr-JcRe-MusW-mfAs-WCct-u4iV-W0pmG3" device = "/dev/md4" # Hint only status = ["ALLOCATABLE"] flags = [] dev_size = 1953519872 # 931.511 Gigabytes pe_start = 384 pe_count = 238466 # 931.508 Gigabytes } pv4 { id = "KZron2-pPTr-ZYeQ-PKXX-4Woq-6aNc-AG4rRJ" device = "/dev/md5" # Hint only status = ["ALLOCATABLE"] flags = [] dev_size = 3907028992 # 1.81935 Terabytes pe_start = 384 pe_count = 476932 # 1.81935 Terabytes } }

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• how to adjust the size of the root partition on live arch linux system (/dev/mapper/arch_root-image)

  - by leon

  Summary: I created a bootable usb drive with a live Bridge linux (ARCH based) on it. Everything works fine. The live system mounts a device called /dev/mapper/arch_root-image as its ext4 root partition (/ mount point). The problem is that I dont know how to control the size of this partition. This is not a Bridge specific issue (also happens with Archbang) Detail: My usb drive has a dos partition table with 2 ext2 partitions $ fdisk -l /dev/sdb Disk /dev/sdb: 29,8 GiB, 32006733824 bytes, 62513152 sectors Unités : secteur de 1 × 512 = 512 octets Taille de secteur (logique / physique) : 512 octets / 512 octets taille d'E/S (minimale / optimale) : 512 octets / 512 octets Type d'étiquette de disque : dos Identifiant de disque : 0x0007b7e2 Périphérique Amorçage Début Fin Blocs Id Système /dev/sdb1 * 2048 2002943 1000448 83 Linux /dev/sdb2 2002944 32258047 15127552 83 Linux sdb1 is approx 1GB and sdb2 is 14GB. The live system is on sdb1. sdb2 is empty. Now when I boot the live system, its filesystem looks like this: $ mount proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) sys on /sys type sysfs (rw,nosuid,nodev,noexec,relatime) dev on /dev type devtmpfs (rw,nosuid,relatime,size=505272k,nr_inodes=126318,mode=755) run on /run type tmpfs (rw,nosuid,nodev,relatime,mode=755) /dev/sda1 on /run/archiso/bootmnt type ext2 (ro,relatime) cowspace on /run/archiso/cowspace type tmpfs (rw,relatime,size=772468k,mode=755) /dev/loop0 on /run/archiso/sfs/root-image type squashfs (ro,relatime) /dev/mapper/arch_root-image on / type ext4 (rw,relatime) securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev) devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000) tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,mode=755) cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd) pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime) cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset) cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct,cpu) cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory) cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices) cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer) cgroup on /sys/fs/cgroup/net_cls type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls) cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio) mqueue on /dev/mqueue type mqueue (rw,relatime) debugfs on /sys/kernel/debug type debugfs (rw,relatime) hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime) configfs on /sys/kernel/config type configfs (rw,relatime) systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=36,pgrp=1,timeout=300,minproto=5,maxproto=5,direct) tmpfs on /tmp type tmpfs (rw) tmpfs on /etc/pacman.d/gnupg type tmpfs (rw,relatime,mode=755) As we can see, the root partition is from the device /dev/mapper/arch_root-image and my problem is that the live system recognizes it as a 3.9GB drive $ df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/arch_root-image 3.9G 1.9G 2.1G 48% / dev 494M 0 494M 0% /dev run 503M 23M 481M 5% /run /dev/sda1 962M 590M 324M 65% /run/archiso/bootmnt cowspace 755M 32M 723M 5% /run/archiso/cowspace /dev/loop0 520M 520M 0 100% /run/archiso/sfs/root-image tmpfs 503M 132K 503M 1% /dev/shm tmpfs 503M 0 503M 0% /sys/fs/cgroup tmpfs 503M 360K 503M 1% /tmp tmpfs 503M 896K 503M 1% /etc/pacman.d/gnupg My question is how is this size controled? I suspect this is related to the content of the aitab file which is part of the Bridge iso image: $ cat aitab # <img> <mnt> <arch> <sfs_comp> <fs_type> <fs_size> root-image / i686 xz ext4 50% I have read https://wiki.archlinux.org/index.php/archiso#aitab but found no clue

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• A failed disk (Pay for professional service or SpinRite?)(new edit)

  - by huggie

  EDIT: After much negotiating and begging and seeing through promotion smoke screen, thanks to the nice representative who took my case, I now know that the engineer has already fixed my NTFS partition (I guess it might be a bad block in the partition table?). She told me that the problem was considered minor, and I should be able to boot normally and just copy stuff out. Whew..I'm glad I didn't agree to the NTD $16,000 deal. New question (should this be in a new thread?): is it safer to use the linux "dd" command or is it better to boot normally into Windows XP and just copy stuff out? EDIT2: Thanks to all the help. I give the best answer to Console as it's most directed related to my question. But many suggestion are helpful and informational. ---- ORIGINAL POST BELOW --- Hi, in my previous post (You don't need to read but it's at http://superuser.com/questions/48838/windows-xp-a-disk-read-error-occurred), I said that my hard disk was not booting and is showing "a disk read error occurred". I took it to a recovery professional. A representative responded today told me that the NTFS partitions have a "NTFS partition system crash". I have no idea what that means. The engineer handling my drive will not be available for contact till tomorrow. Now the company charges me NTD (New Taiwan Dollar) $16,000 to recover lost data, that's kind of a lot considering that my graduate student monthly stipend is currently NTD $32,000 (max. allowed by regulation, may be lower, may change depend on funding). Now I'm weighting in between the options. Option A: let the professional recovers it with the half of my monthly stipend. If file/directories I designated are not recovered I don't pay a penny. (other than the initial examination fee of NTD $1000 which I've already paid.) Option B: let me try SpinRite, if failed, back to Option A. I spoke to the representative at the company they recommended me not to handle it on my own (yeah of course that's what they all want to say, right?), and at the price tag the disk error is probably relatively minor and data recoverable. But the representative really did not have detailed information of the disk failure so I didn't take her recommendation readily. Though one thing I heed was that she said that what they would do is to duplicate the disk before attempting discovery, so there would be no data loss (Is this true? can't duplicating invoke further data loss?). That sounds very good to me. Or maybe a third option: Option C: Negotiate with them to pay them to duplicate the disk hopefully for a much smaller price tag. Let me try SpinRite, if failed, back to Option A. This is a difficult decision. Ultimately I want my data back, but if a cheaper way is available to achieve the same thing... Can operating with SpinRite also corrupt data in someway? I've no idea what happened to my drive. I'll attempt to contact the engineer and hope to get it clarified and make an edit here.

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• Backup, Migrate or Clone Failing CentOS 4 (LVM)

  - by Hegelworm

  I've been running a BlueQuartz CentOS 4 system (Nuonce.net distro) for a few years now and although the hard drive (Deskstar) has always been a bit noisy, on a few recent occasions I've heard it having trouble spinning up. Basically, I want to clone this drive to a similar sized one (80 Gig). I've spent many hours reading upon dd, dd_rescue, rsync, clonezilla and LVM mirroring yet the sheer number of options and nightmarish accounts has left me frozen - unable to make an informed decision as to how to start. I've made a few attempts. dd failed after about 2 hours, as, although the drives appeared to be identical on the surface (ATA Seagate Barracudas, Thai not Chinese), the destination drive is slightly smaller. My most recent attempt involved using a Debian CD to format the new drive and then rsync-ing everything over and editing the new drive's grub and fstab to reflect the changes. No joy here either as I hadn't chosen LVM when partitioning the destination drive and it wouldn't boot. As you can probably tell, I'm out of my depth here and a panic-invoking mixture of caution and frustration has prompted me to sign up here. The server itself, although not strictly a production environment, has a very specific installation of Festival, LAME and ffMpeg and provides the back-end for a Text-to-Speech jQuery plugin that I've built over the last 2 years. I'm also planning to rebuild the whole TTS system on Debian as the existing CentOS system still has PHP4 etc. For now though, I'd really like to just shift everything over to a new drive. As this is my first post, please feel free to lay any house rules on me that I might've overlooked; I've been hovering around StackOverflow for a while now but have only just signed up. Many thanks. Update: Thanks for your responses so far - it's much appreciated and makes me feel a little more confident when I can double-check things here. I had the idea of doing a fresh install of CentOS (from the original disk) on the new drive so the partitions and LVM were all set up correctly (after disconnecting my source drive to prevent painful mistakes). I then booted into rescue mode from the same CD, and, to avoid a conflicting label, changed the /boot partition's label using e2label to /bootnew. I then changed the VolGroup name using lvm vgrename from VolGroup00 to VolGroup001. I could then boot with both drives in. After mounting the new drive (via its VolGroup001 alias) into /newhd, I rsync-ed over everything I could to the new drive, using -avr switches and backslashes. Like mentioned here. I then disconnected my original source drive again, booted from the liveCD again, changed back the boot partition label from /bootnew to /boot using e2label and then renamed the VolGroup back to VolGroup00. I then rebooted and it went through the familiar start-up routine only to not find a host of files in proc, usr, lib, var etc. The boot did complete but there were lots of red 'FAILS'. I could log in with my existing creds, but the network was kaput, I couldn't startX (desktop GUI) and there were also a few (a lot) of error messages pertaining to iptables. Back to square one. I naively thought I'd nailed it. Shall I just buy a bigger hard drive and attempt the dd route? I've read that this can mess with LVM setups and there's the added risk of working on two unmounted drives at once with a low-level tool. Thanks again.

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• Introducing Oracle VM Server for SPARC

  - by Honglin Su

  As you are watching Oracle's Virtualization Strategy Webcast and exploring the great virtualization offerings of Oracle VM product line, I'd like to introduce Oracle VM Server for SPARC --  highly efficient, enterprise-class virtualization solution for Sun SPARC Enterprise Systems with Chip Multithreading (CMT) technology. Oracle VM Server for SPARC, previously called Sun Logical Domains, leverages the built-in SPARC hypervisor to subdivide supported platforms' resources (CPUs, memory, network, and storage) by creating partitions called logical (or virtual) domains. Each logical domain can run an independent operating system. Oracle VM Server for SPARC provides the flexibility to deploy multiple Oracle Solaris operating systems simultaneously on a single platform. Oracle VM Server also allows you to create up to 128 virtual servers on one system to take advantage of the massive thread scale offered by the CMT architecture. Oracle VM Server for SPARC integrates both the industry-leading CMT capability of the UltraSPARC T1, T2 and T2 Plus processors and the Oracle Solaris operating system. This combination helps to increase flexibility, isolate workload processing, and improve the potential for maximum server utilization. Oracle VM Server for SPARC delivers the following: Leading Price/Performance - The low-overhead architecture provides scalable performance under increasing workloads without additional license cost. This enables you to meet the most aggressive price/performance requirement Advanced RAS - Each logical domain is an entirely independent virtual machine with its own OS. It supports virtual disk mutipathing and failover as well as faster network failover with link-based IP multipathing (IPMP) support. Moreover, it's fully integrated with Solaris FMA (Fault Management Architecture), which enables predictive self healing. CPU Dynamic Resource Management (DRM) - Enable your resource management policy and domain workload to trigger the automatic addition and removal of CPUs. This ability helps you to better align with your IT and business priorities. Enhanced Domain Migrations - Perform domain migrations interactively and non-interactively to bring more flexibility to the management of your virtualized environment. Improve active domain migration performance by compressing memory transfers and taking advantage of cryptographic acceleration hardware. These methods provide faster migration for load balancing, power saving, and planned maintenance. Dynamic Crypto Control - Dynamically add and remove cryptographic units (aka MAU) to and from active domains. Also, migrate active domains that have cryptographic units. Physical-to-virtual (P2V) Conversion - Quickly convert an existing SPARC server running the Oracle Solaris 8, 9 or 10 OS into a virtualized Oracle Solaris 10 image. Use this image to facilitate OS migration into the virtualized environment. Virtual I/O Dynamic Reconfiguration (DR) - Add and remove virtual I/O services and devices without needing to reboot the system. CPU Power Management - Implement power saving by disabling each core on a Sun UltraSPARC T2 or T2 Plus processor that has all of its CPU threads idle. Advanced Network Configuration - Configure the following network features to obtain more flexible network configurations, higher performance, and scalability: Jumbo frames, VLANs, virtual switches for link aggregations, and network interface unit (NIU) hybrid I/O. Official Certification Based On Real-World Testing - Use Oracle VM Server for SPARC with the most sophisticated enterprise workloads under real-world conditions, including Oracle Real Application Clusters (RAC). Affordable, Full-Stack Enterprise Class Support - Obtain worldwide support from Oracle for the entire virtualization environment and workloads together. The support covers hardware, firmware, OS, virtualization, and the software stack. SPARC Server Virtualization Oracle offers a full portfolio of virtualization solutions to address your needs. SPARC is the leading platform to have the hard partitioning capability that provides the physical isolation needed to run independent operating systems. Many customers have already used Oracle Solaris Containers for application isolation. Oracle VM Server for SPARC provides another important feature with OS isolation. This gives you the flexibility to deploy multiple operating systems simultaneously on a single Sun SPARC T-Series server with finer granularity for computing resources.  For SPARC CMT processors, the natural level of granularity is an execution thread, not a time-sliced microsecond of execution resources. Each CPU thread can be treated as an independent virtual processor. The scheduler is naturally built into the CPU for lower overhead and higher performance. Your organizations can couple Oracle Solaris Containers and Oracle VM Server for SPARC with the breakthrough space and energy savings afforded by Sun SPARC Enterprise systems with CMT technology to deliver a more agile, responsive, and low-cost environment. Management with Oracle Enterprise Manager Ops Center The Oracle Enterprise Manager Ops Center Virtualization Management Pack provides full lifecycle management of virtual guests, including Oracle VM Server for SPARC and Oracle Solaris Containers. It helps you streamline operations and reduce downtime. Together, the Virtualization Management Pack and the Ops Center Provisioning and Patch Automation Pack provide an end-to-end management solution for physical and virtual systems through a single web-based console. This solution automates the lifecycle management of physical and virtual systems and is the most effective systems management solution for Oracle's Sun infrastructure. Ease of Deployment with Configuration Assistant The Oracle VM Server for SPARC Configuration Assistant can help you easily create logical domains. After gathering the configuration data, the Configuration Assistant determines the best way to create a deployment to suit your requirements. The Configuration Assistant is available as both a graphical user interface (GUI) and terminal-based tool. Oracle Solaris Cluster HA Support The Oracle Solaris Cluster HA for Oracle VM Server for SPARC data service provides a mechanism for orderly startup and shutdown, fault monitoring and automatic failover of the Oracle VM Server guest domain service. In addition, applications that run on a logical domain, as well as its resources and dependencies can be controlled and managed independently. These are managed as if they were running in a classical Solaris Cluster hardware node. Supported Systems Oracle VM Server for SPARC is supported on all Sun SPARC Enterprise Systems with CMT technology. UltraSPARC T2 Plus Systems ·   Sun SPARC Enterprise T5140 Server ·   Sun SPARC Enterprise T5240 Server ·   Sun SPARC Enterprise T5440 Server ·   Sun Netra T5440 Server ·   Sun Blade T6340 Server Module ·   Sun Netra T6340 Server Module UltraSPARC T2 Systems ·   Sun SPARC Enterprise T5120 Server ·   Sun SPARC Enterprise T5220 Server ·   Sun Netra T5220 Server ·   Sun Blade T6320 Server Module ·   Sun Netra CP3260 ATCA Blade Server Note that UltraSPARC T1 systems are supported on earlier versions of the software.Sun SPARC Enterprise Systems with CMT technology come with the right to use (RTU) of Oracle VM Server, and the software is pre-installed. If you have the systems under warranty or with support, you can download the software and system firmware as well as their updates. Oracle Premier Support for Systems provides fully-integrated support for your server hardware, firmware, OS, and virtualization software. Visit oracle.com/support for information about Oracle's support offerings for Sun systems. For more information about Oracle's virtualization offerings, visit oracle.com/virtualization.

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• Getting Started with Media Browser for Windows Media Center

  - by DigitalGeekery

  If you are a Windows Media Center user, you’ll really want to check out Media Browser. The Media Browser plug-in for Windows Media Center takes your digital media files and displays them in a visually appealing, user friendly interface, complete with images and metadata. Requirements Windows 7 or Vista Microsoft .Net 3.5 Framework  Preparing your Media Files For Media Browser to be able to automatically download images and metadata for your media libraries, your files will have to be correctly named. For example, if you have an mp4 file of the movie Batman Begins, it needs to be named Batman Begins.mp4. It cannot be Batmanbegins.mp4 or Batman-begins.mp4. Otherwise, it’s unlikely that Media Browser will display images and metadata. If you find some of your files aren’t pulling cover art or metadata, double-check the official title of the media on a site like IMBD.com. TV Show files TV show files are handled a bit differently. Every TV series in your collection must have a main folder with the show’s name and individual subfolders for each season. Here is an example of folder structure and supported naming conventions. TV Shows\South Park\Season 1\s01e01 – episode 1.mp4 TV Shows\South Park\Season 1\South Park 1×01 – episode 1.mp4 TV Shows\South Park\Season 1\101 – episode 1.mp4  Note: You need to always have a Season 1 folder even if the show only has only one season. If you have several seasons of a particular show, but don’t happen to have Season 1, simply create a blank season 1 folder. Without a season 1 folder, other seasons will not display properly. Installation and Configuration Download and run the latest Media Browser .msi file by taking the defaults. (Download link below) When you reach the final window, leave the “Configure initial settings” box checked, and click “Finish.” You may get a pop up window informing you that folder permissions are not set correctly for Media Browser. Click “Yes.” Adding Your Media The Browser Configuration Tool should have opened automatically. If not, you can open it by going to Start > All Programs > Media Browser > Media Browser Configuration Wizard. To begin adding media files, click “Add.” Browse for a folder that contains media files and click “OK.” Here we are adding a folder with a group of movie files. You can add multiple folders to each media library. For example, if you have movie files stored in 4 or 5 different folders, you can add them all under a single library in Media Browser.  To add additional folders, click the “Add” button on the right side under your currently added folder. The “Add” button to the left will add an additional Media Library, such as one for TV Shows. When you are finished, close out of the Media Browser Configuration Tool. Open Windows Media Center. You will see Media Browser tile on the main interface. Click to open it. When you initially open Media Browser, you will be prompted to run the initial configuration. Click “OK.” You will see a few general configuration options. The important option is the Metadata. Leave this option checked (it is by default) if you wish to pull images & other metadata for your media. When finished, click “Continue,” and then “OK” to restart Media Browser. When you re-enter Media Browser you’ll see your Media Categories listed below, and recently added files in the main display. Click on a Media Library to view the files.   Click “View” at the top to check out some of the different display options to choose from. Below you see can “Detail.” This presents your videos in a list to the left. When you hover over a title, the synopsis and cover art is displayed to the right. “Cover Flow” displays your titles in a right to left format with mirror cover art. “Thumb Strip” displays your titles in a strip along the bottom with a synopsis, image, and movie data above. Configurations Settings and options can be changed through the Media Browser Configuration Tool, or directly in Media Browser by clicking on the “Wrench” at the bottom right of the main Media Browser page. Certain settings may only be available in one location or the other. Some will be available in both places.   Plug-ins and Themes Media Browser features a variety of Plug-ins and Themes that can add optional customization and slick visual appeal. To install plug-ins or themes, open the Media Browser Configuration Tool. Click on the “plug-ins” tab, and then the “More Plug-ins…” button. Note: Clicking on “Advanced” at the top will reveal several additional configuration tabs. Browse the list of plug-ins on the left. When you find want you like, select it and then click “Install.” When the install is complete, you’ll see them listed under “Installed Plug-ins.” To activate any installed theme, click on the “Display” tab. Select it from the Visual Theme drop down list. Close out of the Media Browser Configuration Tool when finished. Some themes, such as the “Diamond” theme shown below, include optional views and settings which can be accessed through a configuration button at the top of the screen. Clicking on the movie gives you additional images and information such as a synopsis, runtime, IMDB rating…   … and even actors and character names.   All that’s left is to hit “Play” when you’re ready to watch.   Conclusion Media Browser is a fantastic plug-in that brings an entirely different level of media management and aesthetics to Windows Media Center. There are numerous additional customizations and configurations we have not covered here such as adding film trailers, music support, and integrating Recorded TV. Media Browser will run on both Windows 7 and Vista. Extenders are also supported but may require additional configuration. Download Media Browser Similar Articles Productive Geek Tips Using Netflix Watchnow in Windows Vista Media Center (Gmedia)Schedule Updates for Windows Media CenterIntegrate Hulu Desktop and Windows Media Center in Windows 7Add Color Coding to Windows 7 Media Center Program GuideIntegrate Boxee with Media Center in Windows 7 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 If it were only this easy SyncToy syncs Files and Folders across Computers on a Network (or partitions on the same drive) Classic Cinema Online offers 100’s of OnDemand Movies OutSync will Sync Photos of your Friends on Facebook and Outlook Windows 7 Easter Theme YoWindoW, a real time weather screensaver

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• SSIS Lookup component tuning tips

  - by jamiet

  Yesterday evening I attended a London meeting of the UK SQL Server User Group at Microsoft’s offices in London Victoria. As usual it was both a fun and informative evening and in particular there seemed to be a few questions arising about tuning the SSIS Lookup component; I rattled off some comments and figured it would be prudent to drop some of them into a dedicated blog post, hence the one you are reading right now. Scene setting A popular pattern in SSIS is to use a Lookup component to determine whether a record in the pipeline already exists in the intended destination table or not and I cover this pattern in my 2006 blog post Checking if a row exists and if it does, has it changed? (note to self: must rewrite that blog post for SSIS2008). Fundamentally the SSIS lookup component (when using FullCache option) sucks some data out of a database and holds it in memory so that it can be compared to data in the pipeline. One of the big benefits of using SSIS dataflows is that they process data one buffer at a time; that means that not all of the data from your source exists in the dataflow at the same time and is why a SSIS dataflow can process data volumes that far exceed the available memory. However, that only applies to data in the pipeline; for reasons that are hopefully obvious ALL of the data in the lookup set must exist in the memory cache for the duration of the dataflow’s execution which means that any memory used by the lookup cache will not be available to be used as a pipeline buffer. Moreover, there’s an obvious correlation between the amount of data in the lookup cache and the time it takes to charge that cache; the more data you have then the longer it will take to charge and the longer you have to wait until the dataflow actually starts to do anything. For these reasons your goal is simple: ensure that the lookup cache contains as little data as possible. General tips Here is a simple tick list you can follow in order to tune your lookups: Use a SQL statement to charge your cache, don’t just pick a table from the dropdown list made available to you. (Read why in SELECT *... or select from a dropdown in an OLE DB Source component?) Only pick the columns that you need, ignore everything else Make the database columns that your cache is populated from as narrow as possible. If a column is defined as VARCHAR(20) then SSIS will allocate 20 bytes for every value in that column – that is a big waste if the actual values are significantly less than 20 characters in length. Do you need DT_WSTR typed columns or will DT_STR suffice? DT_WSTR uses twice the amount of space to hold values that can be stored using a DT_STR so if you can use DT_STR, consider doing so. Same principle goes for the numerical datatypes DT_I2/DT_I4/DT_I8. Only populate the cache with data that you KNOW you will need. In other words, think about your WHERE clause! Thinking outside the box It is tempting to build a large monolithic dataflow that does many things, one of which is a Lookup. Often though you can make better use of your available resources by, well, mixing things up a little and here are a few ideas to get your creative juices flowing: There is no rule that says everything has to happen in a single dataflow. If you have some particularly resource intensive lookups then consider putting that lookup into a dataflow all of its own and using raw files to pass the pipeline data in and out of that dataflow. Know your data. If you think, for example, that the majority of your incoming rows will match with only a small subset of your lookup data then consider chaining multiple lookup components together; the first would use a FullCache containing that data subset and the remaining data that doesn’t find a match could be passed to a second lookup that perhaps uses a NoCache lookup thus negating the need to pull all of that least-used lookup data into memory. Do you need to process all of your incoming data all at once? If you can process different partitions of your data separately then you can partition your lookup cache as well. For example, if you are using a lookup to convert a location into a [LocationId] then why not process your data one region at a time? This will mean your lookup cache only has to contain data for the location that you are currently processing and with the ability of the Lookup in SSIS2008 and beyond to charge the cache using a dynamically built SQL statement you’ll be able to achieve it using the same dataflow and simply loop over it using a ForEach loop. Taking the previous data partitioning idea further … a dataflow can contain more than one data path so why not split your data using a conditional split component and, again, charge your lookup caches with only the data that they need for that partition. Lookups have two uses: to (1) find a matching row from the lookup set and (2) put attributes from that matching row into the pipeline. Ask yourself, do you need to do these two things at the same time? After all once you have the key column(s) from your lookup set then you can use that key to get the rest of attributes further downstream, perhaps even in another dataflow. Are you using the same lookup data set multiple times? If so, consider the file caching option in SSIS 2008 and beyond. Above all, experiment and be creative with different combinations. You may be surprised at what works. Final  thoughts If you want to know more about how the Lookup component differs in SSIS2008 from SSIS2005 then I have a dedicated blog post about that at Lookup component gets a makeover. I am on a mini-crusade at the moment to get a BULK MERGE feature into the database engine, the thinking being that if the database engine can quickly merge massive amounts of data in a similar manner to how it can insert massive amounts using BULK INSERT then that’s a lot of work that wouldn’t have to be done in the SSIS pipeline. If you think that is a good idea then go and vote for BULK MERGE on Connect. If you have any other tips to share then please stick them in the comments. Hope this helps! @Jamiet Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Use an Ubuntu Live CD to Securely Wipe Your PC’s Hard Drive

  - by Trevor Bekolay

  Deleting files or quickly formatting a drive isn’t enough for sensitive personal information. We’ll show you how to get rid of it for good using a Ubuntu Live CD. When you delete a file in Windows, Ubuntu, or any other operating system, it doesn’t actually destroy the data stored on your hard drive, it just marks that data as “deleted.” If you overwrite it later, then that data is generally unrecoverable, but if the operating system don’t happen to overwrite it, then your data is still stored on your hard drive, recoverable by anyone who has the right software. By securely delete files or entire hard drives, your data will be gone for good. Note: Modern hard drives are extremely sophisticated, as are the experts who recover data for a living. There is no guarantee that the methods covered in this article will make your data completely unrecoverable; however, they will make your data unrecoverable to the majority of recovery methods, and all methods that are readily available to the general public. Shred individual files Most of the data stored on your hard drive is harmless, and doesn’t reveal anything about you. If there are just a few files that you know you don’t want someone else to see, then the easiest way to get rid of them is a built-in Linux utility called shred. Open a terminal window by clicking on Applications at the top-left of the screen, then expanding the Accessories menu and clicking on Terminal. Navigate to the file that you want to delete using cd to change directories and ls to list the files and folders in the current directory. As an example, we’ve got a file called BankInfo.txt on a Windows NTFS-formatted hard drive. We want to delete it securely, so we’ll call shred by entering the following in the terminal window: shred <file> which is, in our example: shred BankInfo.txt Notice that our BankInfo.txt file still exists, even though we’ve shredded it. A quick look at the contents of BankInfo.txt make it obvious that the file has indeed been securely overwritten. We can use some command-line arguments to make shred delete the file from the hard drive as well. We can also be extra-careful about the shredding process by upping the number of times shred overwrites the original file. To do this, in the terminal, type in: shred –remove –iterations=<num> <file> By default, shred overwrites the file 25 times. We’ll double this, giving us the following command: shred –remove –iterations=50 BankInfo.txt BankInfo.txt has now been securely wiped on the physical disk, and also no longer shows up in the directory listing. Repeat this process for any sensitive files on your hard drive! Wipe entire hard drives If you’re disposing of an old hard drive, or giving it to someone else, then you might instead want to wipe your entire hard drive. shred can be invoked on hard drives, but on modern file systems, the shred process may be reversible. We’ll use the program wipe to securely delete all of the data on a hard drive. Unlike shred, wipe is not included in Ubuntu by default, so we have to install it. Open up the Synaptic Package Manager by clicking on System in the top-left corner of the screen, then expanding the Administration folder and clicking on Synaptic Package Manager. wipe is part of the Universe repository, which is not enabled by default. We’ll enable it by clicking on Settings > Repositories in the Synaptic Package Manager window. Check the checkbox next to “Community-maintained Open Source software (universe)”. Click Close. You’ll need to reload Synaptic’s package list. Click on the Reload button in the main Synaptic Package Manager window. Once the package list has been reloaded, the text over the search field will change to “Rebuilding search index”. Wait until it reads “Quick search,” and then type “wipe” into the search field. The wipe package should come up, along with some other packages that perform similar functions. Click on the checkbox to the left of the label “wipe” and select “Mark for Installation”. Click on the Apply button to start the installation process. Click the Apply button on the Summary window that pops up. Once the installation is done, click the Close button and close the Synaptic Package Manager window. Open a terminal window by clicking on Applications in the top-left of the screen, then Accessories > Terminal. You need to figure our the correct hard drive to wipe. If you wipe the wrong hard drive, that data will not be recoverable, so exercise caution! In the terminal window, type in: sudo fdisk -l A list of your hard drives will show up. A few factors will help you identify the right hard drive. One is the file system, found in the System column of  the list – Windows hard drives are usually formatted as NTFS (which shows up as HPFS/NTFS). Another good identifier is the size of the hard drive, which appears after its identifier (highlighted in the following screenshot). In our case, the hard drive we want to wipe is only around 1 GB large, and is formatted as NTFS. We make a note of the label found under the the Device column heading. If you have multiple partitions on this hard drive, then there will be more than one device in this list. The wipe developers recommend wiping each partition separately. To start the wiping process, type the following into the terminal: sudo wipe <device label> In our case, this is: sudo wipe /dev/sda1 Again, exercise caution – this is the point of no return! Your hard drive will be completely wiped. It may take some time to complete, depending on the size of the drive you’re wiping. Conclusion If you have sensitive information on your hard drive – and chances are you probably do – then it’s a good idea to securely delete sensitive files before you give away or dispose of your hard drive. The most secure way to delete your data is with a few swings of a hammer, but shred and wipe from a Ubuntu Live CD is a good alternative! 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• Analytic functions – they’re not aggregates

  - by Rob Farley

  SQL 2012 brings us a bunch of new analytic functions, together with enhancements to the OVER clause. People who have known me over the years will remember that I’m a big fan of the OVER clause and the types of things that it brings us when applied to aggregate functions, as well as the ranking functions that it enables. The OVER clause was introduced in SQL Server 2005, and remained frustratingly unchanged until SQL Server 2012. This post is going to look at a particular aspect of the analytic functions though (not the enhancements to the OVER clause). When I give presentations about the analytic functions around Australia as part of the tour of SQL Saturdays (starting in Brisbane this Thursday), and in Chicago next month, I’ll make sure it’s sufficiently well described. But for this post – I’m going to skip that and assume you get it. The analytic functions introduced in SQL 2012 seem to come in pairs – FIRST_VALUE and LAST_VALUE, LAG and LEAD, CUME_DIST and PERCENT_RANK, PERCENTILE_CONT and PERCENTILE_DISC. Perhaps frustratingly, they take slightly different forms as well. The ones I want to look at now are FIRST_VALUE and LAST_VALUE, and PERCENTILE_CONT and PERCENTILE_DISC. The reason I’m pulling this ones out is that they always produce the same result within their partitions (if you’re applying them to the whole partition). Consider the following query: SELECT     YEAR(OrderDate),     FIRST_VALUE(TotalDue)         OVER (PARTITION BY YEAR(OrderDate)               ORDER BY OrderDate, SalesOrderID               RANGE BETWEEN UNBOUNDED PRECEDING                         AND UNBOUNDED FOLLOWING),     LAST_VALUE(TotalDue)         OVER (PARTITION BY YEAR(OrderDate)               ORDER BY OrderDate, SalesOrderID               RANGE BETWEEN UNBOUNDED PRECEDING                         AND UNBOUNDED FOLLOWING),     PERCENTILE_CONT(0.95)         WITHIN GROUP (ORDER BY TotalDue)         OVER (PARTITION BY YEAR(OrderDate)),     PERCENTILE_DISC(0.95)         WITHIN GROUP (ORDER BY TotalDue)         OVER (PARTITION BY YEAR(OrderDate)) FROM Sales.SalesOrderHeader ; This is designed to get the TotalDue for the first order of the year, the last order of the year, and also the 95% percentile, using both the continuous and discrete methods (‘discrete’ means it picks the closest one from the values available – ‘continuous’ means it will happily use something between, similar to what you would do for a traditional median of four values). I’m sure you can imagine the results – a different value for each field, but within each year, all the rows the same. Notice that I’m not grouping by the year. Nor am I filtering. This query gives us a result for every row in the SalesOrderHeader table – 31465 in this case (using the original AdventureWorks that dates back to the SQL 2005 days). The RANGE BETWEEN bit in FIRST_VALUE and LAST_VALUE is needed to make sure that we’re considering all the rows available. If we don’t specify that, it assumes we only mean “RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW”, which means that LAST_VALUE ends up being the row we’re looking at. At this point you might think about other environments such as Access or Reporting Services, and remember aggregate functions like FIRST. We really should be able to do something like: SELECT     YEAR(OrderDate),     FIRST_VALUE(TotalDue)         OVER (PARTITION BY YEAR(OrderDate)               ORDER BY OrderDate, SalesOrderID               RANGE BETWEEN UNBOUNDED PRECEDING                         AND UNBOUNDED FOLLOWING) FROM Sales.SalesOrderHeader GROUP BY YEAR(OrderDate) ; But you can’t. You get that age-old error: Msg 8120, Level 16, State 1, Line 5 Column 'Sales.SalesOrderHeader.OrderDate' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause. Msg 8120, Level 16, State 1, Line 5 Column 'Sales.SalesOrderHeader.SalesOrderID' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause. Hmm. You see, FIRST_VALUE isn’t an aggregate function. None of these analytic functions are. There are too many things involved for SQL to realise that the values produced might be identical within the group. Furthermore, you can’t even surround it in a MAX. Then you get a different error, telling you that you can’t use windowed functions in the context of an aggregate. And so we end up grouping by doing a DISTINCT. SELECT DISTINCT     YEAR(OrderDate),         FIRST_VALUE(TotalDue)              OVER (PARTITION BY YEAR(OrderDate)                   ORDER BY OrderDate, SalesOrderID                   RANGE BETWEEN UNBOUNDED PRECEDING                             AND UNBOUNDED FOLLOWING),         LAST_VALUE(TotalDue)             OVER (PARTITION BY YEAR(OrderDate)                   ORDER BY OrderDate, SalesOrderID                   RANGE BETWEEN UNBOUNDED PRECEDING                             AND UNBOUNDED FOLLOWING),     PERCENTILE_CONT(0.95)          WITHIN GROUP (ORDER BY TotalDue)         OVER (PARTITION BY YEAR(OrderDate)),     PERCENTILE_DISC(0.95)         WITHIN GROUP (ORDER BY TotalDue)         OVER (PARTITION BY YEAR(OrderDate)) FROM Sales.SalesOrderHeader ; I’m sorry. It’s just the way it goes. Hopefully it’ll change the future, but for now, it’s what you’ll have to do. If we look in the execution plan, we see that it’s incredibly ugly, and actually works out the results of these analytic functions for all 31465 rows, finally performing the distinct operation to convert it into the four rows we get in the results. You might be able to achieve a better plan using things like TOP, or the kind of calculation that I used in http://sqlblog.com/blogs/rob_farley/archive/2011/08/23/t-sql-thoughts-about-the-95th-percentile.aspx (which is how PERCENTILE_CONT works), but it’s definitely convenient to use these functions, and in time, I’m sure we’ll see good improvements in the way that they are implemented. Oh, and this post should be good for fellow SQL Server MVP Nigel Sammy’s T-SQL Tuesday this month.

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• Listing common SQL Code Smells.

  - by Phil Factor

  Once you’ve done a number of SQL Code-reviews, you’ll know those signs in the code that all might not be well. These ’Code Smells’ are coding styles that don’t directly cause a bug, but are indicators that all is not well with the code. . Kent Beck and Massimo Arnoldi seem to have coined the phrase in the "OnceAndOnlyOnce" page of www.C2.com, where Kent also said that code "wants to be simple". Bad Smells in Code was an essay by Kent Beck and Martin Fowler, published as Chapter 3 of the book ‘Refactoring: Improving the Design of Existing Code’ (ISBN 978-0201485677) Although there are generic code-smells, SQL has its own particular coding habits that will alert the programmer to the need to re-factor what has been written. See Exploring Smelly Code   and Code Deodorants for Code Smells by Nick Harrison for a grounding in Code Smells in C# I’ve always been tempted by the idea of automating a preliminary code-review for SQL. It would be so useful to trawl through code and pick up the various problems, much like the classic ‘Lint’ did for C, and how the Code Metrics plug-in for .NET Reflector by Jonathan 'Peli' de Halleux is used for finding Code Smells in .NET code. The problem is that few of the standard procedural code smells are relevant to SQL, and we need an agreed list of code smells. Merrilll Aldrich made a grand start last year in his blog Top 10 T-SQL Code Smells.However, I'd like to make a start by discovering if there is a general opinion amongst Database developers what the most important SQL Smells are. One can be a bit defensive about code smells. I will cheerfully write very long stored procedures, even though they are frowned on. I’ll use dynamic SQL occasionally. You can only use them as an aid for your own judgment and it is fine to ‘sign them off’ as being appropriate in particular circumstances. Also, whole classes of ‘code smells’ may be irrelevant for a particular database. The use of proprietary SQL, for example, is only a ‘code smell’ if there is a chance that the database will have to be ported to another RDBMS. The use of dynamic SQL is a risk only with certain security models. As the saying goes,  a CodeSmell is a hint of possible bad practice to a pragmatist, but a sure sign of bad practice to a purist. Plamen Ratchev’s wonderful article Ten Common SQL Programming Mistakes lists some of these ‘code smells’ along with out-and-out mistakes, but there are more. The use of nested transactions, for example, isn’t entirely incorrect, even though the database engine ignores all but the outermost: but it does flag up the possibility that the programmer thinks that nested transactions are supported. If anything requires some sort of general agreement, the definition of code smells is one. I’m therefore going to make this Blog ‘dynamic, in that, if anyone twitters a suggestion with a #SQLCodeSmells tag (or sends me a twitter) I’ll update the list here. If you add a comment to the blog with a suggestion of what should be added or removed, I’ll do my best to oblige. In other words, I’ll try to keep this blog up to date. The name against each 'smell' is the name of the person who Twittered me, commented about or who has written about the 'smell'. it does not imply that they were the first ever to think of the smell! Use of deprecated syntax such as *= (Dave Howard) Denormalisation that requires the shredding of the contents of columns. (Merrill Aldrich) Contrived interfaces Use of deprecated datatypes such as TEXT/NTEXT (Dave Howard) Datatype mis-matches in predicates that rely on implicit conversion.(Plamen Ratchev) Using Correlated subqueries instead of a join   (Dave_Levy/ Plamen Ratchev) The use of Hints in queries, especially NOLOCK (Dave Howard /Mike Reigler) Few or No comments. Use of functions in a WHERE clause. (Anil Das) Overuse of scalar UDFs (Dave Howard, Plamen Ratchev) Excessive ‘overloading’ of routines. The use of Exec xp_cmdShell (Merrill Aldrich) Excessive use of brackets. (Dave Levy) Lack of the use of a semicolon to terminate statements Use of non-SARGable functions on indexed columns in predicates (Plamen Ratchev) Duplicated code, or strikingly similar code. Misuse of SELECT * (Plamen Ratchev) Overuse of Cursors (Everyone. Special mention to Dave Levy & Adrian Hills) Overuse of CLR routines when not necessary (Sam Stange) Same column name in different tables with different datatypes. (Ian Stirk) Use of ‘broken’ functions such as ‘ISNUMERIC’ without additional checks. Excessive use of the WHILE loop (Merrill Aldrich) INSERT ... EXEC (Merrill Aldrich) The use of stored procedures where a view is sufficient (Merrill Aldrich) Not using two-part object names (Merrill Aldrich) Using INSERT INTO without specifying the columns and their order (Merrill Aldrich) Full outer joins even when they are not needed. (Plamen Ratchev) Huge stored procedures (hundreds/thousands of lines). Stored procedures that can produce different columns, or order of columns in their results, depending on the inputs. Code that is never used. Complex and nested conditionals WHILE (not done) loops without an error exit. Variable name same as the Datatype Vague identifiers. Storing complex data  or list in a character map, bitmap or XML field User procedures with sp_ prefix (Aaron Bertrand)Views that reference views that reference views that reference views (Aaron Bertrand) Inappropriate use of sql_variant (Neil Hambly) Errors with identity scope using SCOPE_IDENTITY @@IDENTITY or IDENT_CURRENT (Neil Hambly, Aaron Bertrand) Schemas that involve multiple dated copies of the same table instead of partitions (Matt Whitfield-Atlantis UK) Scalar UDFs that do data lookups (poor man's join) (Matt Whitfield-Atlantis UK) Code that allows SQL Injection (Mladen Prajdic) Tables without clustered indexes (Matt Whitfield-Atlantis UK) Use of "SELECT DISTINCT" to mask a join problem (Nick Harrison) Multiple stored procedures with nearly identical implementation. (Nick Harrison) Excessive column aliasing may point to a problem or it could be a mapping implementation. (Nick Harrison) Joining "too many" tables in a query. (Nick Harrison) Stored procedure returning more than one record set. (Nick Harrison) A NOT LIKE condition (Nick Harrison) excessive "OR" conditions. (Nick Harrison) User procedures with sp_ prefix (Aaron Bertrand) Views that reference views that reference views that reference views (Aaron Bertrand) sp_OACreate or anything related to it (Bill Fellows) Prefixing names with tbl_, vw_, fn_, and usp_ ('tibbling') (Jeremiah Peschka) Aliases that go a,b,c,d,e... (Dave Levy/Diane McNurlan) Overweight Queries (e.g. 4 inner joins, 8 left joins, 4 derived tables, 10 subqueries, 8 clustered GUIDs, 2 UDFs, 6 case statements = 1 query) (Robert L Davis) Order by 3,2 (Dave Levy) MultiStatement Table functions which are then filtered 'Sel * from Udf() where Udf.Col = Something' (Dave Ballantyne) running a SQL 2008 system in SQL 2000 compatibility mode(John Stafford)

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• J2EE Applications, SPARC T4, Solaris Containers, and Resource Pools

  - by user12620111

  I've obtained a substantial performance improvement on a SPARC T4-2 Server running a J2EE Application Server Cluster by deploying the cluster members into Oracle Solaris Containers and binding those containers to cores of the SPARC T4 Processor. This is not a surprising result, in fact, it is consistent with other results that are available on the Internet. See the "references", below, for some examples. Nonetheless, here is a summary of my configuration and results. (1.0) Before deploying a J2EE Application Server Cluster into a virtualized environment, many decisions need to be made. I'm not claiming that all of the decisions that I have a made will work well for every environment. In fact, I'm not even claiming that all of the decisions are the best possible for my environment. I'm only claiming that of the small sample of configurations that I've tested, this is the one that is working best for me. Here are some of the decisions that needed to be made: (1.1) Which virtualization option? There are several virtualization options and isolation levels that are available. Options include: Hard partitions:  Dynamic Domains on Sun SPARC Enterprise M-Series Servers Hypervisor based virtualization such as Oracle VM Server for SPARC (LDOMs) on SPARC T-Series Servers OS Virtualization using Oracle Solaris Containers Resource management tools in the Oracle Solaris OS to control the amount of resources an application receives, such as CPU cycles, physical memory, and network bandwidth. Oracle Solaris Containers provide the right level of isolation and flexibility for my environment. To borrow some words from my friends in marketing, "The SPARC T4 processor leverages the unique, no-cost virtualization capabilities of Oracle Solaris Zones"  (1.2) How to associate Oracle Solaris Containers with resources? There are several options available to associate containers with resources, including (a) resource pool association (b) dedicated-cpu resources and (c) capped-cpu resources. I chose to create resource pools and associate them with the containers because I wanted explicit control over the cores and virtual processors.  (1.3) Cluster Topology? Is it best to deploy (a) multiple application servers on one node, (b) one application server on multiple nodes, or (c) multiple application servers on multiple nodes? After a few quick tests, it appears that one application server per Oracle Solaris Container is a good solution. (1.4) Number of cluster members to deploy? I chose to deploy four big 64-bit application servers. I would like go back a test many 32-bit application servers, but that is left for another day. (2.0) Configuration tested. (2.1) I was using a SPARC T4-2 Server which has 2 CPU and 128 virtual processors. To understand the physical layout of the hardware on Solaris 10, I used the OpenSolaris psrinfo perl script available at http://hub.opensolaris.org/bin/download/Community+Group+performance/files/psrinfo.pl: test# ./psrinfo.pl -pv The physical processor has 8 cores and 64 virtual processors (0-63) The core has 8 virtual processors (0-7)   The core has 8 virtual processors (8-15)   The core has 8 virtual processors (16-23)   The core has 8 virtual processors (24-31)   The core has 8 virtual processors (32-39)   The core has 8 virtual processors (40-47)   The core has 8 virtual processors (48-55)   The core has 8 virtual processors (56-63)     SPARC-T4 (chipid 0, clock 2848 MHz) The physical processor has 8 cores and 64 virtual processors (64-127)   The core has 8 virtual processors (64-71)   The core has 8 virtual processors (72-79)   The core has 8 virtual processors (80-87)   The core has 8 virtual processors (88-95)   The core has 8 virtual processors (96-103)   The core has 8 virtual processors (104-111)   The core has 8 virtual processors (112-119)   The core has 8 virtual processors (120-127)     SPARC-T4 (chipid 1, clock 2848 MHz) (2.2) The "before" test: without processor binding. I started with a 4-member cluster deployed into 4 Oracle Solaris Containers. Each container used a unique gigabit Ethernet port for HTTP traffic. The containers shared a 10 gigabit Ethernet port for JDBC traffic. (2.3) The "after" test: with processor binding. I ran one application server in the Global Zone and another application server in each of the three non-global zones (NGZ):  (3.0) Configuration steps. The following steps need to be repeated for all three Oracle Solaris Containers. (3.1) Stop AppServers from the BUI. (3.2) Stop the NGZ. test# ssh test-z2 init 5 (3.3) Enable resource pools: test# svcadm enable pools (3.4) Create the resource pool: test# poolcfg -dc 'create pool pool-test-z2' (3.5) Create the processor set: test# poolcfg -dc 'create pset pset-test-z2' (3.6) Specify the maximum number of CPU's that may be addd to the processor set: test# poolcfg -dc 'modify pset pset-test-z2 (uint pset.max=32)' (3.7) bash syntax to add Virtual CPUs to the processor set: test# (( i = 64 )); while (( i < 96 )); do poolcfg -dc "transfer to pset pset-test-z2 (cpu $i)"; (( i = i + 1 )) ; done (3.8) Associate the resource pool with the processor set: test# poolcfg -dc 'associate pool pool-test-z2 (pset pset-test-z2)' (3.9) Tell the zone to use the resource pool that has been created: test# zonecfg -z test-z1 set pool=pool-test-z2 (3.10) Boot the Oracle Solaris Container test# zoneadm -z test-z2 boot (3.11) Save the configuration to /etc/pooladm.conf test# pooladm -s (4.0) Results. Using the resource pools improves both throughput and response time: (5.0) References: System Administration Guide: Oracle Solaris Containers-Resource Management and Oracle Solaris Zones Capitalizing on large numbers of processors with WebSphere Portal on Solaris WebSphere Application Server and T5440 (Dileep Kumar's Weblog)  http://www.brendangregg.com/zones.html Reuters Market Data System, RMDS 6 Multiple Instances (Consolidated), Performance Test Results in Solaris, Containers/Zones Environment on Sun Blade X6270 by Amjad Khan, 2009.

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• Guide to MySQL & NoSQL, Webinar Q&A

  - by Mat Keep

  0 0 1 959 5469 Homework 45 12 6416 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin; mso-ansi-language:EN-US;} Yesterday we ran a webinar discussing the demands of next generation web services and how blending the best of relational and NoSQL technologies enables developers and architects to deliver the agility, performance and availability needed to be successful. Attendees posted a number of great questions to the MySQL developers, serving to provide additional insights into areas like auto-sharding and cross-shard JOINs, replication, performance, client libraries, etc. So I thought it would be useful to post those below, for the benefit of those unable to attend the webinar. Before getting to the Q&A, there are a couple of other resources that maybe useful to those looking at NoSQL capabilities within MySQL: - On-Demand webinar (coming soon!) - Slides used during the webinar - Guide to MySQL and NoSQL whitepaper  - MySQL Cluster demo, including NoSQL interfaces, auto-sharing, high availability, etc.  So here is the Q&A from the event  Q. Where does MySQL Cluster fit in to the CAP theorem? A. MySQL Cluster is flexible. A single Cluster will prefer consistency over availability in the presence of network partitions. A pair of Clusters can be configured to prefer availability over consistency. A full explanation can be found on the MySQL Cluster & CAP Theorem blog post.  Q. Can you configure the number of replicas? (the slide used a replication factor of 1) Yes. A cluster is configured by an .ini file. The option NoOfReplicas sets the number of originals and replicas: 1 = no data redundancy, 2 = one copy etc. Usually there's no benefit in setting it >2. Q. Interestingly most (if not all) of the NoSQL databases recommend having 3 copies of data (the replication factor).    Yes, with configurable quorum based Reads and writes. MySQL Cluster does not need a quorum of replicas online to provide service. Systems that require a quorum need > 2 replicas to be able to tolerate a single failure. Additionally, many NoSQL systems take liberal inspiration from the original GFS paper which described a 3 replica configuration. MySQL Cluster avoids the need for a quorum by using a lightweight arbitrator. You can configure more than 2 replicas, but this is a tradeoff between incrementally improved availability, and linearly increased cost. Q. Can you have cross node group JOINS? Wouldn't that run into the risk of flooding the network? MySQL Cluster 7.2 supports cross nodegroup joins. A full cross-join can require a large amount of data transfer, which may bottleneck on network bandwidth. However, for more selective joins, typically seen with OLTP and light analytic applications, cross node-group joins give a great performance boost and network bandwidth saving over having the MySQL Server perform the join. Q. Are the details of the benchmark available anywhere? According to my calculations it results in approx. 350k ops/sec per processor which is the largest number I've seen lately The details are linked from Mikael Ronstrom's blog The benchmark uses a benchmarking tool we call flexAsynch which runs parallel asynchronous transactions. It involved 100 byte reads, of 25 columns each. Regarding the per-processor ops/s, MySQL Cluster is particularly efficient in terms of throughput/node. It uses lock-free minimal copy message passing internally, and maximizes ID cache reuse. Note also that these are in-memory tables, there is no need to read anything from disk. Q. Is access control (like table) planned to be supported for NoSQL access mode? Currently we have not seen much need for full SQL-like access control (which has always been overkill for web apps and telco apps). So we have no plans, though especially with memcached it is certainly possible to turn-on connection-level access control. But specifically table level controls are not planned. Q. How is the performance of memcached APi with MySQL against memcached+MySQL or any other Object Cache like Ecache with MySQL DB? With the memcache API we generally see a memcached response in less than 1 ms. and a small cluster with one memcached server can handle tens of thousands of operations per second. Q. Can .NET can access MemcachedAPI? Yes, just use a .Net memcache client such as the enyim or BeIT memcache libraries. Q. Is the row level locking applicable when you update a column through memcached API? An update that comes through memcached uses a row lock and then releases it immediately. Memcached operations like "INCREMENT" are actually pushed down to the data nodes. In most cases the locks are not even held long enough for a network round trip. Q. Has anyone published an example using something like PHP? I am assuming that you just use the PHP memcached extension to hook into the memcached API. Is that correct? Not that I'm aware of but absolutely you can use it with php or any of the other drivers Q. For beginner we need more examples. Take a look here for a fully worked example Q. Can I access MySQL using Cobol (Open Cobol) or C and if so where can I find the coding libraries etc? A. There is a cobol implementation that works well with MySQL, but I do not think it is Open Cobol. Also there is a MySQL C client library that is a standard part of every mysql distribution Q. Is there a place to go to find help when testing and/implementing the NoSQL access? If using Cluster then you can use the [email protected] alias or post on the MySQL Cluster forum Q. Are there any white papers on this?  Yes - there is more detail in the MySQL Guide to NoSQL whitepaper If you have further questions, please don’t hesitate to use the comments below!

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• SQL University: What and why of database refactoring

  - by Mladen Prajdic

  This is a post for a great idea called SQL University started by Jorge Segarra also famously known as SqlChicken on Twitter. It’s a collection of blog posts on different database related topics contributed by several smart people all over the world. So this week is mine and we’ll be talking about database testing and refactoring. In 3 posts we’ll cover: SQLU part 1 - What and why of database testing SQLU part 2 - What and why of database refactoring SQLU part 3 - Tools of the trade This is a second part of the series and in it we’ll take a look at what database refactoring is and why do it. Why refactor a database To know why refactor we first have to know what refactoring actually is. Code refactoring is a process where we change module internals in a way that does not change that module’s input/output behavior. For successful refactoring there is one crucial thing we absolutely must have: Tests. Automated unit tests are the only guarantee we have that we haven’t broken the input/output behavior before refactoring. If you haven’t go back ad read my post on the matter. Then start writing them. Next thing you need is a code module. Those are views, UDFs and stored procedures. By having direct table access we can kiss fast and sweet refactoring good bye. One more point to have a database abstraction layer. And no, ORM’s don’t fall into that category. But also know that refactoring is NOT adding new functionality to your code. Many have fallen into this trap. Don’t be one of them and resist the lure of the dark side. And it’s a strong lure. We developers in general love to add new stuff to our code, but hate fixing our own mistakes or changing existing code for no apparent reason. To be a good refactorer one needs discipline and focus. Now we know that refactoring is all about changing inner workings of existing code. This can be due to performance optimizations, changing internal code workflows or some other reason. This is a typical black box scenario to the outside world. If we upgrade the car engine it still has to drive on the road (preferably faster) and not fly (no matter how cool that would be). Also be aware that white box tests will break when we refactor. What to refactor in a database Refactoring databases doesn’t happen that often but when it does it can include a lot of stuff. Let us look at a few common cases. Adding or removing database schema objects Adding, removing or changing table columns in any way, adding constraints, keys, etc… All of these can be counted as internal changes not visible to the data consumer. But each of these carries a potential input/output behavior change. Dropping a column can result in views not working anymore or stored procedure logic crashing. Adding a unique constraint shows duplicated data that shouldn’t exist. Foreign keys break a truncate table command executed from an application that runs once a month. All these scenarios are very real and can happen. With the proper database abstraction layer fully covered with black box tests we can make sure something like that does not happen (hopefully at all). Changing physical structures Physical structures include heaps, indexes and partitions. We can pretty much add or remove those without changing the data returned by the database. But the performance can be affected. So here we use our performance tests. We do have them, right? Just by adding a single index we can achieve orders of magnitude performance improvement. Won’t that make users happy? But what if that index causes our write operations to crawl to a stop. again we have to test this. There are a lot of things to think about and have tests for. Without tests we can’t do successful refactoring! Fixing bad code We all have some bad code in our systems. We usually refer to that code as code smell as they violate good coding practices. Examples of such code smells are SQL injection, use of SELECT *, scalar UDFs or cursors, etc… Each of those is huge code smell and can result in major code changes. Take SELECT * from example. If we remove a column from a table the client using that SELECT * statement won’t have a clue about that until it runs. Then it will gracefully crash and burn. Not to mention the widely unknown SELECT * view refresh problem that Tomas LaRock (@SQLRockstar on Twitter) and Colin Stasiuk (@BenchmarkIT on Twitter) talk about in detail. Go read about it, it’s informative. Refactoring this includes replacing the * with column names and most likely change to application using the database. Breaking apart huge stored procedures Have you ever seen seen a stored procedure that was 2000 lines long? I have. It’s not pretty. It hurts the eyes and sucks the will to live the next 10 minutes. They are a maintenance nightmare and turn into things no one dares to touch. I’m willing to bet that 100% of time they don’t have a single test on them. Large stored procedures (and functions) are a clear sign that they contain business logic. General opinion on good database coding practices says that business logic has no business in the database. That’s the applications part. Refactoring such behemoths requires writing lots of edge case tests for the stored procedure input/output behavior and then start to refactor it. First we split the logic inside into smaller parts like new stored procedures and UDFs. Those then get called from the master stored procedure. Once we’ve successfully modularized the database code it’s best to transfer that logic into the applications consuming it. This only leaves the stored procedure with common data manipulation logic. Of course this isn’t always possible so having a plethora of performance and behavior unit tests is absolutely necessary to confirm we’ve actually improved the codebase in some way.   Refactoring is not a popular chore amongst developers or managers. The former don’t like fixing old code, the latter can’t see the financial benefit. Remember how we talked about being lousy at estimating future costs in the previous post? But there comes a time when it must be done. Hopefully I’ve given you some ideas how to get started. In the last post of the series we’ll take a look at the tools to use and an example of testing and refactoring.

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• I Clobbered a Leopard with a Window Last Night

  - by D'Arcy Lussier

  I’ve had my 15” Mac Book Pro for a little over a year now, and its hands-down the best laptop I’ve ever owned…hardware wise. And I tried, I really really tried, to like OSX. I even bought Parallels so I could run Windows 7 and all my development tools while still trying to live in an OSX world. But in the end, I missed Windows too much. There were just too many shortcomings with OSX that kept me from being productive. For one thing, Office for Mac is *not* Office for Windows. The applications are written by different teams, and Excel on the Mac is just different enough to be painful. The VM experience was adequate, but my MBP would heat up like crazy when running it and the experience trying to get Windows apps to interact with an OSX file system was awkward. And I found I was in the VM more than I thought I’d be. iMovie is not as easy to use for doing simple movie editing as Windows Movie Maker. There’s no free blog editing software for OSX that’s on par with Windows Live Writer. And really, all I was using OSX for was Twitter (which I can use a Windows client for) and web browsing (also something Windows can provide obviously). So I had to ask myself – why am I forcing myself to use an operating system I don’t like, on a laptop that can support Windows 7? And so I paved my MBP and am happily running Windows 7 on it…and its fantastic! All the good stuff with the hardware is still there with the goodness of Win 7. Happy happy. I did run into some snags doing this though, and that’s really what this blog post is about – things to be aware of if you want to install Win 7 directly on your MBP metal. First, Ensure You Have Your Original Mac Install Disk This was a warning my buddy Dylan, who’s been running Win 7 on his MBP for a while now, gave me early on. The reason you need that original disk is that the hardware drivers you need are all located there. Apparently you can’t easily download them, so make sure you have them ahead of time. Second, Forget BootCamp The only reason you need BootCamp is if you still want the option to boot into OSX. If you don’t, then you don’t need BootCamp. In fact, you don’t even need BootCamp to install Win 7. What you *will* need though is a DVD with Win 7 burnt on it. Apple doesn’t support bootable USB drives. Well, actually they do for Mac Book Airs which don’t come with optical drives…but to get it working you’ll need to edit a system file of BootCamp so your make of MBP is included in an XML document, and even then you *still* are using BootCamp meaning you’ll be making an OSX partition. So don’t worry about BootCamp, just burn a Windows 7 disc, put it into the DVD drive, and restart your MBP. Third, Know The Secret Commands So after putting in the Windows 7 DVD and restarting your MBP, you’ll want to hold down the ‘C’ key during boot up. This tells the MBP that it should boot from the DVD drive instead of the hard drive. Interestingly, it appears you don’t have to do this if its the Mac OSX install disc (more on that in a second), but regardless – hold down C and Windows will start the install process. Next up is the partition process. You’ll notice that there’s a partition called ETI or something like that. This has to do with the drive format that Apple uses and how they partition their system drives. What I did – I blew it away! At first I didn’t, but I was told I couldn’t install Windows on the remaining space due to the different drive format. Blowing away the ETI partition (and all other partitions) allowed me to continue the Windows install. *REMEMBER –  No warranty is provided or implied, just telling you what I did and how I got it to work. Ok, so now Windows is installed and I’m rebooting. Everything looks good, but I need drivers! So I put in the OSX install DVD and run the BootCamp assistant which installs all the Windows drivers I need. Fantastic! Oh, I need to restart – no problem. OH NO, PROBLEM! I left the OSX install DVD in the drive and now the MBP wants to boot from the drive and install OSX! I’m not holding down the C key, what the heck?! Ok, well there must be a way to eject this disk…hmm…no physical button on the side…the eject button doesn’t seem to work on the keyboard…no little pin hole to insert something to force the disc out…well what the…?! It turns out, if you want to eject a disc at boot up, you need (and I kid you not) to plug a mouse into the laptop and hold down the right-click button while its booting. This ejected the disc for me. Seriously. Finally, Things You Should Be Aware Of Once you have Windows up and running there’s a few things you need to be aware of, mainly new keyboard shortcuts. For instance, on the Mac keyboard there is no Home, End, PageUp or PageDown. There’s also no obvious way to do something like select large amounts of text (like you would by holding Shift-Home at the end of a line of text for instance). So here’s some shortcuts you need to know: Home – fn + left arrow End – fn + right arrow Select a line of text as you would with the Home key – Shift + fn + left arrow Select a line of text as you would with the End key – Shift + fn + right arrow Page Up – fn + up arrow Page Down – fn + down arrow Also, you’ll notice that the awesome Mac track pad doesn’t respond to taps as clicks. No fear, this is just a setting that needs to be altered in the BootCamp control panel (that controls the Mac Hardware-specific settings within Windows, you can access it easily from the system tray icon) One other thing, battery life seems a bit lower than with OSX, but then again I’m also doing more than Twitter or web browsing on this thing now. Conclusion My laptop runs awesome now that I have Windows 7 on there. It’s obviously up to individual taste, but for me I just didn’t see benefits to living in an OSX world when everything I needed lived in Windows. And also, I finally am back to an operating system that doesn’t require me to eject a USB drive before physically removing it! It’s 2012 folks, how has this not been fixed?! D

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• Oracle Certification and virtualization Solutions.

  - by scoter

  As stated in official MOS ( My Oracle Support ) document 249212.1 support for Oracle products on non-Oracle VM platforms follow exactly the same stance as support for VMware and, so, the only x86 virtualization software solution certified for any Oracle product is "Oracle VM". Based on the fact that: Oracle VM is totally free ( you have the option to buy Oracle-Support ) Certified is pretty different from supported ( OracleVM is certified, others could be supported ) With Oracle VM you may not require to reproduce your issue(s) on physical server Oracle VM is the only x86 software solution that allows hard-partitioning *** *** see details to these Oracle public links: http://www.oracle.com/technetwork/server-storage/vm/ovm-hardpart-168217.pdf http://www.oracle.com/us/corporate/pricing/partitioning-070609.pdf people started asking to migrate from third party virtualization software (ex. RH KVM, VMWare) to Oracle VM. Migrating RH KVM guest to Oracle VM. OracleVM has a built-in P2V utility ( Official Documentation ) but in some cases we can't use it, due to : network inaccessibility between hypervisors ( KVM and OVM ) network slowness between hypervisors (KVM and OVM) size of the guest virtual-disks Here you'll find a step-by-step guide to "manually" migrate a guest machine from KVM to OVM. 1. Verify source guest characteristics. Using KVM web console you can verify characteristics of the guest you need to migrate, such as: CPU Cores details Defined Memory ( RAM ) Name of your guest Guest operating system Disks details ( number and size ) Network details ( number of NICs and network configuration ) 2. Export your guest in OVF / OVA format.  The export from Redhat KVM ( kernel virtual machine ) will create a structured export of your guest: [root@ovmserver1 mnt]# lltotal 12drwxrwx--- 5 36 36 4096 Oct 19 2012 b8296fca-13c4-4841-a50f-773b5139fcee b8296fca-13c4-4841-a50f-773b5139fcee is the ID of the guest exported from RH-KVM [root@ovmserver1 mnt]# cd b8296fca-13c4-4841-a50f-773b5139fcee/[root@ovmserver1 b8296fca-13c4-4841-a50f-773b5139fcee]# ls -ltrtotal 12drwxr-x--- 4 36 36 4096 Oct 19  2012 masterdrwxrwx--- 2 36 36 4096 Oct 29  2012 dom_mddrwxrwx--- 4 36 36 4096 Oct 31  2012 images images contains your virtual-disks exported [root@ovmserver1 b8296fca-13c4-4841-a50f-773b5139fcee]# cd images/[root@ovmserver1 images]# ls -ltratotal 16drwxrwx--- 5 36 36 4096 Oct 19  2012 ..drwxrwx--- 2 36 36 4096 Oct 31  2012 d4ef928d-6dc6-4743-b20d-568b424728a5drwxrwx--- 2 36 36 4096 Oct 31  2012 4b241ea0-43aa-4f3b-ab7d-2fc633b491a1drwxrwx--- 4 36 36 4096 Oct 31  2012 .[root@ovmserver1 images]# cd d4ef928d-6dc6-4743-b20d-568b424728a5/[root@ovmserver1 d4ef928d-6dc6-4743-b20d-568b424728a5]# ls -ltotal 5169092-rwxr----- 1 36 36 187904819200 Oct 31  2012 4c03b1cf-67cc-4af0-ad1e-529fd665dac1-rw-rw---- 1 36 36          341 Oct 31  2012 4c03b1cf-67cc-4af0-ad1e-529fd665dac1.meta[root@ovmserver1 d4ef928d-6dc6-4743-b20d-568b424728a5]# file 4c03b1cf-67cc-4af0-ad1e-529fd665dac14c03b1cf-67cc-4af0-ad1e-529fd665dac1: LVM2 (Linux Logical Volume Manager) , UUID: sZL1Ttpy0vNqykaPahEo3hK3lGhwspv 4c03b1cf-67cc-4af0-ad1e-529fd665dac1 is the first exported disk ( physical volume ) [root@ovmserver1 d4ef928d-6dc6-4743-b20d-568b424728a5]# cd ../4b241ea0-43aa-4f3b-ab7d-2fc633b491a1/[root@ovmserver1 4b241ea0-43aa-4f3b-ab7d-2fc633b491a1]# ls -ltotal 5568076-rwxr----- 1 36 36 107374182400 Oct 31  2012 9020f2e1-7b8a-4641-8f80-749768cc237a-rw-rw---- 1 36 36          341 Oct 31  2012 9020f2e1-7b8a-4641-8f80-749768cc237a.meta[root@ovmserver1 4b241ea0-43aa-4f3b-ab7d-2fc633b491a1]# file 9020f2e1-7b8a-4641-8f80-749768cc237a9020f2e1-7b8a-4641-8f80-749768cc237a: x86 boot sector; partition 1: ID=0x83, active, starthead 1, startsector 63, 401562 sectors; partition 2: ID=0x82, starthead 0, startsector 401625, 65529135 sectors; startsector 63, 401562 sectors; partition 2: ID=0x82, starthead 0, startsector 401625, 65529135 sectors; partition 3: ID=0x83, starthead 254, startsector 65930760, 8385930 sectors; partition 4: ID=0x5, starthead 254, startsector 74316690, 135395820 sectors, code offset 0x48 9020f2e1-7b8a-4641-8f80-749768cc237a is the second exported disk, with partition 1 bootable 3. Prepare the new guest on Oracle VM. By Ovm-Manager we can prepare the guest where we will move the exported virtual-disks; under the Tab "Servers and VMs": click on  and create your guest with parameters collected before (point 1): - add NICs on different networks: - add virtual-disks; in this case we add two disks of 1.0 GB each one; we will extend the virtual disk copying the source KVM virtual-disk ( see next steps ) - verify virtual-disks created ( under Repositories tab ) 4. Verify OVM virtual-disks names. [root@ovmserver1 VirtualMachines]# grep -r hyptest_rdbms * 0004fb0000060000a906b423f44da98e/vm.cfg:OVM_simple_name = 'hyptest_rdbms' [root@ovmserver1 VirtualMachines]# cd 0004fb0000060000a906b423f44da98e [root@ovmserver1 0004fb0000060000a906b423f44da98e]# more vm.cfgvif = ['mac=00:21:f6:0f:3f:85,bridge=0004fb001089128', 'mac=00:21:f6:0f:3f:8e,bridge=0004fb00101971d'] OVM_simple_name = 'hyptest_rdbms' vnclisten = '127.0.0.1' disk = ['file:/OVS/Repositories/0004fb00000300004f17b7368139eb41/ VirtualDisks/0004fb000012000097c1bfea9834b17d.img,xvda,w', 'file:/OVS/Repositories/0004fb00000300004f17b7368139eb41/VirtualDisks/ 0004fb0000120000cde6a11c3cb1d0be.img,xvdb,w'] vncunused = '1' uuid = '0004fb00-0006-0000-a906-b423f44da98e' on_reboot = 'restart' cpu_weight = 27500 memory = 32768 cpu_cap = 0 maxvcpus = 8 OVM_high_availability = True maxmem = 32768 vnc = '1' OVM_description = '' on_poweroff = 'destroy' on_crash = 'restart' name = '0004fb0000060000a906b423f44da98e' guest_os_type = 'linux' builder = 'hvm' vcpus = 8 keymap = 'en-us' OVM_os_type = 'Oracle Linux 5' OVM_cpu_compat_group = '' OVM_domain_type = 'xen_hvm' disk2 ovm ==> /OVS/Repositories/0004fb00000300004f17b7368139eb41/VirtualDisks/ 0004fb0000120000cde6a11c3cb1d0be.img disk1 ovm ==> /OVS/Repositories/0004fb00000300004f17b7368139eb41/VirtualDisks/ 0004fb000012000097c1bfea9834b17d.img Summarizing disk1 --source ==> /mnt/b8296fca-13c4-4841-a50f-773b5139fcee/images/4b241ea0-43aa-4f3b-ab7d-2fc633b491a1/9020f2e1-7b8a-4641-8f80-749768cc237a disk1 --dest ==> /OVS/Repositories/0004fb00000300004f17b7368139eb41/VirtualDisks/ 0004fb000012000097c1bfea9834b17d.img disk2 --source ==> /mnt/b8296fca-13c4-4841-a50f-773b5139fcee/images/d4ef928d-6dc6-4743-b20d-568b424728a5/4c03b1cf-67cc-4af0-ad1e-529fd665dac1 disk2 --dest ==> /OVS/Repositories/0004fb00000300004f17b7368139eb41/VirtualDisks/ 0004fb0000120000cde6a11c3cb1d0be.img 5. Copy KVM exported virtual-disks to OVM virtual-disks. Keeping your Oracle VM guest stopped you can copy KVM exported virtual-disks to OVM virtual-disks; what I did is only to locally mount the filesystem containing the exported virtual-disk ( by an usb device ) on my OVS; the copy automatically resize OVM virtual-disks ( previously created with a size of 1GB ) . nohup cp /mnt/b8296fca-13c4-4841-a50f-773b5139fcee/images/4b241ea0-43aa-4f3b-ab7d-2fc633b491a1/9020f2e1-7b8a-4641-8f80-749768cc237a /OVS/Repositories/0004fb00000300004f17b7368139eb41/VirtualDisks/0004fb000012000097c1bfea9834b17d.img & nohup cp /mnt/b8296fca-13c4-4841-a50f-773b5139fcee/images/d4ef928d-6dc6-4743-b20d-568b424728a5/4c03b1cf-67cc-4af0-ad1e-529fd665dac1 /OVS/Repositories/0004fb00000300004f17b7368139eb41/VirtualDisks/0004fb0000120000cde6a11c3cb1d0be.img & 7. When copy completed refresh repository to aknowledge the new-disks size. 7. After "refresh repository" is completed, start guest machine by Oracle VM manager. After the first start of your guest: - verify that you can see all disks and partitions - verify that your guest is network reachable ( MAC Address of your NICs changed ) Eventually you can also evaluate to convert your guest to PVM ( Paravirtualized virtual Machine ) following official Oracle documentation. Ciao Simon COTER ps: next-time I'd like to post an article reporting how to manually migrate Virtual-Iron guests to OracleVM.  Comments and corrections are welcome. 

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• straight to grub prompt on boot

  - by cheshirekow

  I am very lost. I did a fresh install of Ubuntu 10.04 on a laptop. First reboot was fine. I ran all the recommended upgrades, and now every time I start I get just a grub>_ prompt. No error message, just the prompt, and a little banner at the top saying grub's version and telling me that I have minimal bash style editing. I've tried: 1) Re-installing grub via sudo grub-install sda (There is only one disk with only two partitions, one primary, and one for swap) 2) Changed GRUB_HIDDEN_TIMEOUT=10 GRUB_TIMEOUT=30 GRUB_CMDLINE_LINUX_DEFAULT="rootdelay=90" GRUB_CMDLINE_LINUX="rootdelay=90" in /etc/default/grub. No luck. I can boot with the following: grub> set root=(hd0,1) grub> probe (hd0,1) -u c00fadde-f7e8-45e7-a4da-0235605f756 grub> linux /boot/vmlinuz-2.6.32-21-generic root=UUID=c00fadde-f7e8-45e7-a4da-0235605f756 rootdelay=90 grub> initrd /boot/initrd.img-2.6.32-21-generic grub> boot And then everything seems to be fine from there. From the grub prompt if I try configfile /boot/grub/grub.cfg The screen clears and I get another grub prompt. So, seriously, what could the problem be? edit: Full text of /boot/grub/grub.cfg # # DO NOT EDIT THIS FILE # # It is automatically generated by /usr/sbin/grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then load_env fi set default="0" if [ ${prev_saved_entry} ]; then set saved_entry=${prev_saved_entry} save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z ${boot_once} ]; then saved_entry=${chosen} save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n ${have_grubenv} ]; then if [ -z ${boot_once} ]; then save_env recordfail; fi; fi } insmod ext2 set root='(hd0,1)' search --no-floppy --fs-uuid --set c00fadde-f7e8-45e7-a4da-0235c605f756 if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=640x480 insmod gfxterm insmod vbe if terminal_output gfxterm ; then true ; else # For backward compatibility with versions of terminal.mod that don't # understand terminal_output terminal gfxterm fi fi insmod ext2 set root='(hd0,1)' search --no-floppy --fs-uuid --set c00fadde-f7e8-45e7-a4da-0235c605f756 set locale_dir=($root)/boot/grub/locale set lang=en insmod gettext if [ ${recordfail} = 1 ]; then set timeout=-1 else set timeout=30 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### set menu_color_normal=white/black set menu_color_highlight=black/light-gray ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### menuentry 'Ubuntu, with Linux 2.6.32-21-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod ext2 set root='(hd0,1)' search --no-floppy --fs-uuid --set c00fadde-f7e8-45e7-a4da-0235c605f756 linux /boot/vmlinuz-2.6.32-21-generic root=UUID=c00fadde-f7e8-45e7-a4da-0235c605f756 ro rootdelay=90 rootdelay=90 initrd /boot/initrd.img-2.6.32-21-generic } menuentry 'Ubuntu, with Linux 2.6.32-21-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod ext2 set root='(hd0,1)' search --no-floppy --fs-uuid --set c00fadde-f7e8-45e7-a4da-0235c605f756 echo 'Loading Linux 2.6.32-21-generic ...' linux /boot/vmlinuz-2.6.32-21-generic root=UUID=c00fadde-f7e8-45e7-a4da-0235c605f756 ro single rootdelay=90 echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-2.6.32-21-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod ext2 set root='(hd0,1)' search --no-floppy --fs-uuid --set c00fadde-f7e8-45e7-a4da-0235c605f756 linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod ext2 set root='(hd0,1)' search --no-floppy --fs-uuid --set c00fadde-f7e8-45e7-a4da-0235c605f756 linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### if [ ${timeout} != -1 ]; then if sleep --verbose --interruptible 10 ; then set timeout=0 fi fi ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### output of update-grub Generating grub.cfg ... Found linux image: /boot/vmlinuz-2.6.32-21-generic Found initrd image: /boot/initrd.img-2.6.32-21-generic Found memtest86+ image: /boot/memtest86+.bin done contents of /boot total 14280 -rw-r--r-- 1 root root 640617 2010-04-16 09:01 abi-2.6.32-21-generic -rw-r--r-- 1 root root 115847 2010-04-16 09:01 config-2.6.32-21-generic drwxr-xr-x 3 root root 4096 2010-09-08 02:42 grub -rw-r--r-- 1 root root 7968754 2010-09-02 01:49 initrd.img-2.6.32-21-generic -rw-r--r-- 1 root root 160280 2010-03-23 05:37 memtest86+.bin -rw-r--r-- 1 root root 1687378 2010-04-16 09:01 System.map-2.6.32-21-generic -rw-r--r-- 1 root root 1196 2010-04-16 09:03 vmcoreinfo-2.6.32-21-generic -rw-r--r-- 1 root root 4029792 2010-04-16 09:01 vmlinuz-2.6.32-21-generic

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• /dev/sda1 not a subset of /dev/sda?

  - by Guillaume Brunerie

  Hi, the first entry of my partition table is: $ sudo hexdump -Cv -n 16 -s 446 /dev/sda 000001be 80 01 01 00 83 fe ff ff 3f 00 00 00 81 1c 20 03 |........?..... .| (-Cv describe the output format, -n 16 asks for 16 bytes and -s 446 skips the first 446 bytes) You can see that my first partition is a primary Linux partition and that this partition begin at sector 63 (see for example here for the structure of the partition table). I would then expect that except for the first 63 sectors and the other partitions, /dev/sda1 and /dev/sda are exactly the same. But this is not the case, the sector #2 of /dev/sda1 is not exactly the same as the sector #65 of /dev/sda (but they are very similar, only 16 bytes are different): $ sudo hexdump -Cv -n 512 -s 65b /dev/sda 00008200 00 20 19 00 90 03 64 00 2d 00 05 00 5a 2f 56 00 |. ....d.-...Z/V.| 00008210 b6 b1 16 00 00 00 00 00 02 00 00 00 02 00 00 00 |................| 00008220 00 80 00 00 00 80 00 00 00 20 00 00 d8 38 ee 4c |......... ...8.L| 00008230 9a 01 ef 4c 05 00 24 00 53 ef 01 00 01 00 00 00 |...L..$.S.......| 00008240 59 23 e9 4c 00 4e ed 00 00 00 00 00 01 00 00 00 |Y#.L.N..........| 00008250 00 00 00 00 0b 00 00 00 00 01 00 00 3c 00 00 00 |............<...| 00008260 42 02 00 00 7b 00 00 00 85 23 eb f2 71 67 44 f5 |B...{....#..qgD.| 00008270 bb 8f 6f f2 3a 59 ff 4d 55 62 75 6e 74 75 00 00 |..o.:Y.MUbuntu..| 00008280 00 00 00 00 00 00 00 00 2f 75 62 75 6e 74 75 00 |......../ubuntu.| 00008290 d8 3c df 5d 00 88 ff ff 52 d0 ef 1d 00 00 00 00 |.<.]....R.......| 000082a0 c0 40 51 b6 00 88 ff ff 00 4e c8 bb 00 88 ff ff |[email protected]......| 000082b0 c0 f6 86 b8 00 88 ff ff 30 2e 0d a0 ff ff ff ff |........0.......| 000082c0 38 3d df 5d 00 88 ff ff 00 00 00 00 00 00 fe 03 |8=.]............| 000082d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000082e0 08 00 00 00 00 00 00 00 00 00 00 00 8a 53 d3 0e |.............S..| 000082f0 7c 7a 43 e4 8b fb ca e0 72 b7 fa c8 01 01 00 00 ||zC.....r.......| 00008300 00 00 00 00 00 00 00 00 16 4c 47 4b 0a f3 03 00 |.........LGK....| 00008310 04 00 00 00 00 00 00 00 00 00 00 00 fe 7f 00 00 |................| 00008320 24 b7 0c 00 fe 7f 00 00 01 00 00 00 22 37 0d 00 |$..........."7..| 00008330 ff 7f 00 00 01 00 00 00 23 37 0d 00 00 00 00 00 |........#7......| 00008340 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 08 |................| 00008350 00 00 00 00 00 00 00 00 00 00 00 00 1c 00 1c 00 |................| 00008360 01 00 00 00 e9 7f 00 00 00 00 00 00 00 00 00 00 |................| 00008370 00 00 00 00 04 00 00 00 9f 7d bb 00 00 00 00 00 |.........}......| 00008380 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00008390 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000083a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000083b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000083c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000083d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000083e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000083f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| versus $ sudo hexdump -Cv -n 512 -s 2b /dev/sda1 00000400 00 20 19 00 90 03 64 00 2d 00 05 00 5a 2f 56 00 |. ....d.-...Z/V.| 00000410 b6 b1 16 00 00 00 00 00 02 00 00 00 02 00 00 00 |................| 00000420 00 80 00 00 00 80 00 00 00 20 00 00 df 76 ef 4c |......... ...v.L| 00000430 df 76 ef 4c 06 00 24 00 53 ef 01 00 01 00 00 00 |.v.L..$.S.......| 00000440 59 23 e9 4c 00 4e ed 00 00 00 00 00 01 00 00 00 |Y#.L.N..........| 00000450 00 00 00 00 0b 00 00 00 00 01 00 00 3c 00 00 00 |............<...| 00000460 46 02 00 00 7b 00 00 00 85 23 eb f2 71 67 44 f5 |F...{....#..qgD.| 00000470 bb 8f 6f f2 3a 59 ff 4d 55 62 75 6e 74 75 00 00 |..o.:Y.MUbuntu..| 00000480 00 00 00 00 00 00 00 00 2f 75 62 75 6e 74 75 00 |......../ubuntu.| 00000490 d8 3c df 5d 00 88 ff ff 52 d0 ef 1d 00 00 00 00 |.<.]....R.......| 000004a0 c0 40 51 b6 00 88 ff ff 00 4e c8 bb 00 88 ff ff |[email protected]......| 000004b0 c0 f6 86 b8 00 88 ff ff 30 2e 0d a0 ff ff ff ff |........0.......| 000004c0 38 3d df 5d 00 88 ff ff 00 00 00 00 00 00 fe 03 |8=.]............| 000004d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000004e0 08 00 00 00 00 00 00 00 00 00 00 00 8a 53 d3 0e |.............S..| 000004f0 7c 7a 43 e4 8b fb ca e0 72 b7 fa c8 01 01 00 00 ||zC.....r.......| 00000500 00 00 00 00 00 00 00 00 16 4c 47 4b 0a f3 03 00 |.........LGK....| 00000510 04 00 00 00 00 00 00 00 00 00 00 00 fe 7f 00 00 |................| 00000520 24 b7 0c 00 fe 7f 00 00 01 00 00 00 22 37 0d 00 |$..........."7..| 00000530 ff 7f 00 00 01 00 00 00 23 37 0d 00 00 00 00 00 |........#7......| 00000540 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 08 |................| 00000550 00 00 00 00 00 00 00 00 00 00 00 00 1c 00 1c 00 |................| 00000560 01 00 00 00 e9 7f 00 00 00 00 00 00 00 00 00 00 |................| 00000570 00 00 00 00 04 00 00 00 a3 7d bb 00 00 00 00 00 |.........}......| 00000580 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00000590 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000005a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000005b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000005c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000005d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000005e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000005f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| For example in the third line, there is a 8.L in the first hexdump and v.L in the second. Why are there differences?

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• Strategy for using snapshots to back up Ubuntu Linux server?

  - by MountainX

  I need some backup advice for my home file server. Here are the mount points, volume groups, logical volumes and used/total space of all the volumes on my Ubuntu 8.10 home file server. / vgA/lvRoot [7.5G/50G] /tmp vgB/lvTmp [195M/30G] /var vgB/lvVar [780M/30G] swap vgB/lvSwap [16.00 GB] /media1 vgC/lvMedia1 [400G/975G] /media2 vgC/lvMedia2 [75G/295G] /boot partition (no volume group) [95M/200M] /video partition (no volume group) [450G/950G] /backups vgD/lvBackupTarget [800G/925G] /home vgE/lvHome [85G/200G] I have just added a 2.0 TB external USB drive that I would like to use to backup everything. (It will be a close fit to get it all on one 2.0 TB drive. I actually have a 2nd external USB drive if needed.) I'd like to backup "/", var, /media1, media2 and /home. I'll deal with /boot and /video separately since they are not logical volumes. For all the logical volumes I'm anticipating taking snapshots and then copying those snapshots to the 2.0 TB external USB drive. I have never done a task like that before. If I do that, I could use the tutorial I found here: http://www.howtoforge.com/linux_lvm_snapshots My questions are: What is the best overall strategy? Is it LVM snapshots, as I'm assuming? How should I prepare, subdivide and mount the 2.0 TB external USB drive? 2.a. Should I create one or more regular partitions or should I create a physical volume with one or more logical volumes? 2.b. Would it be advisable to extactly mirror the source pv/lv layout on the external drive, and if so, is this a good strategy? What's the best way to get the snapshots onto the external drive? dd? Even though this is a strategy question, feedback with actual commands is appreciated. I need step-by-step cookbook-style help because I don't do much server admin work. (Background: This is a home file server that I have rarely had to touch in about 2 years. It has done its job without much intervention. The really old PC that I used to back everything up recently failed, so I'm replacing that with the external USB drive(s) and I'd like to upgrade my backup strategy at the same time. Previously, I just copied stuff from /backups over to the other computer and that would not have made things very easy in a real restore situation. The /backups mount point contains backup copies of "most" of the important data on a file by file basis, but it does not contain copies of /boot, etc. BTW, the actual internal HDD that holds /backups is separate from the other storage devices.) EDIT: I'll propose a strategy... The idea came from a comment here: LVM mirroring VS RAID1 "LVM mirrors are for replication of a logical volume to a different physical volume. It's essentially meant to "move the data to a different disk". The mirror is then broken..." That would fit my requirements well. Here is an ideal situation: establish the LV mirror on the external drive break the link with the mirror create a (persistent) snapshot on the mirror after a week, resync the mirror with the original source and update the mirror break the link and create another snapshot on the mirror. Obviously, the mirror will be like a weekly full backup. And the snapshots on the mirror will represent earlier points in time. If this would work and if it would be time efficient, it would give a nice full & differential type backup on the external drive based on LVM. I have not heard of a strategy like this before. Will it work? Could it be scripted? Thoughts? EDIT 2: Creating Portable DiskSafes With LoopbackFS And LVM Snapshots This article seems intriguing: http://www.howtoforge.com/creating-portable-disksafes-with-loopbackfs-and-lvm-snapshots Unfortunately, I don't understand exactly how to map those ideas to the strategy I'm proposing above. I'm going to ask this last bit as a separate question. I will leave my original question in place because I still desire feedback on the overall best strategy. At this moment I'm assuming it is LVM mirroring in the style of "Creating Portable DiskSafes with LVM Snapshots" but that might be wrong.

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• western digital caviar black. EXT4-fs error [migrated]

  - by azat

  Recently I update my HDD on desktop machine, and bought WD Caviar Black. But after I format & copy information to it (using dd), and fix partitions size: I have next errors in kern.log: Aug 27 16:04:35 home-spb kernel: [148265.326264] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9054, 32254 clusters in bitmap, 32258 in gd Aug 27 16:07:11 home-spb kernel: [148421.493483] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9045, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:17 home-spb kernel: [148546.481693] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 10299, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:17 home-spb kernel: [148546.487147] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.258711] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4345, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.277591] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.278202] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4344, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.284760] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.291983] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9051, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.297495] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.297916] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9050, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.297940] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.303213] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4425, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.312127] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.312487] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4424, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.317858] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.322231] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4336, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.326250] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.326599] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4335, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.332397] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.341957] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 5764, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.350709] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.351127] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 5763, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.355916] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:43 home-spb kernel: [148572.401055] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 10063, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:43 home-spb kernel: [148572.404357] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:43 home-spb kernel: [148572.414699] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 10073, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:43 home-spb kernel: [148572.420411] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:43 home-spb kernel: [148572.493933] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9059, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:43 home-spb kernel: [148572.493956] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. One time, machine rebooted (not manually), when I turn it on, it runs fsck on /dev/sdc2 and fix some errors and some files are missing on /dev/sdc2 I'v check /dev/sdc2 for badblocks, it doesn't have it ( using e2fsck -c /dev/sdc2 ) Here is the output of fsck http://pastebin.com/D5LmLVBY What else I can do to understand what's wrong here? BTW for /dev/sdc1 no message like that, in kern.log Linux version: 3.3.0 Distributive: Debian wheezy

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