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• Allignment of ext3 partition on LVM RAID volume group

  - by John P

  I'm trying to add a partition on a LVM that resides on a RAID6 volume group and fdisk is complaining about the partition not residing on a physical sector boundry. My question is, how do you calculate the correct starting sector for a partition on a LVM? This partition will be formated ext3. Would it be better to just format the LVM directly instead of creating a new partition? Disk /dev/dedvol/backup: 2199.0 GB, 2199023255552 bytes 255 heads, 63 sectors/track, 267349 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 1048576 bytes / 8388608 bytes Disk identifier: 0x4e428f49 Device Boot Start End Blocks Id System /dev/dedvol/backup1 63 267349 2146982827+ 83 Linux Partition 1 does not start on physical sector boundary. lvdisplay /dev/dedvol/backup --- Logical volume --- LV Name /dev/dedvol/backup VG Name dedvol LV UUID OV2n5j-7LHb-exJL-t8dI-dU8A-2vxf-uIicCt LV Write Access read/write LV Status available # open 0 LV Size 2.00 TiB Current LE 524288 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 32768 Block device 253:1 vgdisplay dedvol --- Volume group --- VG Name dedvol System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 3 VG Access read/write VG Status resizable MAX LV 0 Cur LV 2 Open LV 1 Max PV 0 Cur PV 1 Act PV 1 VG Size 14.55 TiB PE Size 4.00 MiB Total PE 3815448 Alloc PE / Size 3670016 / 14.00 TiB Free PE / Size 145432 / 568.09 GiB VG UUID 8fBcOk-aXGx-P3Qy-VVpJ-0zK1-fQgy-Cb691J

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• Can enabling a RAID controller's writeback cache harm overall performance?

  - by Nathan O'Sullivan

  I have an 8 drive RAID 10 setup connected to an Adaptec 5805Z, running Centos 5.5 and deadline scheduler. A basic dd read test shows 400mb/sec, and a basic dd write test shows about the same. When I run the two simultaneously, I see the read speed drop to ~5mb/sec while the write speed stays at more or less the same 400mb/sec. The output of iostat -x as you would expect, shows that very few read transactions are being executed while the disk is bombarded with writes. If i turn the controller's writeback cache off, I dont see a 50:50 split but I do see a marked improvement, somewhere around 100mb/s reads and 300mb/s writes. I've also found if I lower the nr_requests setting on the drive's queue (somewhere around 8 seems optimal) I can end up with 150mb/sec reads and 150mb/sec writes; ie. a reduction in total throughput but certainly more suitable for my workload. Is this a real phenomenon? Or is my synthetic test too simplistic? The reason this could happen seems clear enough, when the scheduler switches from reads to writes, it can run heaps of write requests because they all just land in the controllers cache but must be carried out at some point. I would guess the actual disk writes are occuring when the scheduler starts trying to perform reads again, resulting in very few read requests being executed. This seems a reasonable explanation, but it also seems like a massive drawback to using writeback cache on an system with non-trivial write loads. I've been searching for discussions around this all afternoon and found nothing. What am I missing?

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• Am I getting the right memory for my motherboard?

  - by Daniel Carvalho

  Hi technophiles; I have a Gigabyte GA-EP45-DS motherboard. Also, the memory that came with my computer was two Transcend aXe RAM 1066MHZ 1GB modules. The thing is, I noticed that my motherboard has "DDR2 1200" written on it. This concerns me, have I bought slower memory than my computer is supposed to have ideally? Now, I'm not super concerned at a granular level about the best optimal RAM with the best CAS latency etc... but I do hope at least that I've got the right speed. Now, as far as I know, there is no such thing as ram at 1200MHZ? Am I right? You see, because I'm thinking of getting more RAM now, before I can't find the same type or speed any-more and just want to make sure it's the right thing. Furthermore, if the memory is slower than what I should be getting for my motherboard, what RAM should I be getting, and will that new RAM play nice with my old RAM? If I get new RAM at a different speed, would it be better / more beneficial performance-wise to omit the old RAM because of how the whole DUAL channel RAM thing works? I'm not too clued up on this area. Thanks chiefs.

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• Simplest DNS solution for remote offices

  - by dunxd

  I look after a bunch of remote offices that connect via VPN - a Cisco ASA 5505 in each office acts as Firewall and VPN end point. Beyond that we keep things as simple as possible in the offices to minimise the support burden. We don't have any kind of server except in offices large enough to justify having someone dedicated to IT. Basically there is the ASA, some computers, a network printer and a switch. One of the problems I am seeing in a lot of offices is that DNS requests looking up hosts inside our network often fail - I'm assuming timeouts due to the offices internet connection (they are all in developing world countries) having some sub-optimal qualities (e.g. high latency caused by VSAT segments, or packet loss. The obvious solution to this is to have some sort of local DNS service that can serve local requests - so I think it would need to do zone transfers from our Microsoft Windows 2008 R2 DNS servers at HQ. However, simply installing Windows Servers in each office is both expensive, and creates a support burden. This got me thinking about pfsense/m0n0wall on embedded devices - those can act as a DNS server, and could be configured at HQ and sent out as just something that needs to be plugged into the network and can then be forgotten about by the staff locally. Maybe there are some alternatives to the ASA 5505 that include some DNS functionality. Has anyone here dealt with the problem, either using some kind of embedded device, or found some other solution? Any gotchas or reasons to avoid what I have suggested?

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• Dual-booting Ubuntu and Pardus with GRUB2...Pardus no show?

  - by Ibn Ali al-Turki

  I have Ubuntu 10.10 installed and used to dual-boot Fedora, but I replaced Fedora with Pardus. After the install, I went into ubuntu, and did a sudo update-grub. It detected my Pardus 2011 install there. When I rebooted, it did not show up in my grub2 menu however. I went back to Ubuntu and did it again...then checked the grub.cfg, and it is not there. I have read that Pardus uses a grub legacy. How can I get Pardus into my grub2 menu? Thanks! sudo fdisk -l Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xd9b3496e Device Boot Start End Blocks Id System /dev/sda1 * 1 15197 122067968 83 Linux /dev/sda2 36394 60802 196059757 5 Extended /dev/sda3 15197 30394 122067968 83 Linux /dev/sda5 36394 59434 185075308 7 HPFS/NTFS /dev/sda6 59434 60802 10983424 82 Linux swap / Solaris Partition table entries are not in disk order and update-grub Found linux image: /boot/vmlinuz-2.6.35-25-generic Found initrd image: /boot/initrd.img-2.6.35-25-generic Found memtest86+ image: /boot/memtest86+.bin Found Pardus 2011 (2011) on /dev/sda3 Yet after this, I go to grub.cfg, and Pardus is not there.

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• Nginx : Proper use of limit_req_zone and limit_req

  - by xperator

  I have 2 website running on VPS. Their purpose is sharing music files and publishing news. Both of them use wordpress. What I am trying is that I want to prevent little hackers from flooding the webserver and putting stress on the server to make it crash. The problem is that after using limit_req_zone and limit_req my website became very slow. Browsing Wordpress control panel takes a long long time. I tried changing values but it didn't improve much. I guess the problem is Wordpress because it's the only script I am using on both front and back end. Here is the last setting which seems to be more responsive than others : limit_req_zone $binary_remote_addr zone=flood:5m rate=10r/m; location ~ \.php$ { limit_req zone=flood burst=100 nodelay; } What are the optimal values that should be used in my case (wp) ? I want the website have it's normal behavior, On the other hand stopping lifeless people from flooding. Another question, Is it safe and enough to use limit_req only on php files ?

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• Is my OCZ SSD aligned correctly? (Linux)

  - by Barney Gumble

  I have an OCZ Agility 2 SSD with 40 GB of space. I use it as a system drive in Debian Linux (Squeeze) and in my opinion it's really fast. But I've read a lot on aligning partitions and file systems... And I'm not sure if I succeeded in aligning the partitions correctly. Maybe the SSD could be even faster?? ;-) I use ext4 and here is the output of fdisk -cul: Disk /dev/sda: 40.0 GB, 40018599936 bytes 255 heads, 63 sectors/track, 4865 cylinders, total 78161328 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: [...] Device Boot Start End Blocks Id System /dev/sda1 * 2048 73242623 36620288 83 Linux /dev/sda2 73244670 78159871 2457601 5 Extended /dev/sda5 73244672 78159871 2457600 82 Linux swap / Solaris My partitions were created just by the Debian Squeeze setup assistant. So I didn't care about the details of partitioning. But now I think maybe the installer didn't align it correctly? Actually, 2048 looks good to me (better than odd values like 63 or something like that) but I've no idea... ;-) Help plz! According to some "SSD Alignment Calculator" I found on the web, the OCZ SSDs have a NAND Erase Block Size of 512kB and their NAND Page Size is 4kB. 2048 is divisible by 4 and 512. So are the partitions aligned correctly?

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• Ubuntu 12.04/12.10 can't detect windows or any other partitions(Asus z77 UEFI BIOS)

  - by user971155

  I've recently completed tinkering my new pc(motherboard ASUS z77 with UEFI BIOS) and unfortunately not everything works quite well. After installing windows 7 ultimate on a single primary partition(SATA drive) I decided to allocate one more logical partition for additional needs. When I tried doing it with the manager - it said that it couldn't allocate requested size even though I certainly asked for much less than it was available. I thought that it might have been a windows issue and proceded to installing Ubuntu 12.10 x64. When the graphical interface loaded it showed me a message stating that it can't find any other operating system on the drive. When I used custom partioning option it showed me none of my current partions(including that with windows). However, when I boot with "Try Ubuntu" feature it does find them ! I find it weird though. Here's what the console present me with: ubuntu@ubuntu:~$ sudo os-prober /dev/sda1:Windows 7 (loader):Windows:chain ubuntu@ubuntu:~$ sudo fdisk -l Disk /dev/sda: 640.1 GB, 640135028736 bytes 255 heads, 63 sectors/track, 77825 cylinders, total 1250263728 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00072b98 Device Boot Start End Blocks Id System /dev/sda1 * 2048 206847 102400 7 HPFS/NTFS/exFAT /dev/sda2 206848 100020223 49906688 7 HPFS/NTFS/exFAT /dev/sda3 100022270 1250263039 575120385 5 Extended /dev/sda4 566669312 1250263039 341796864 83 Linux I also tried creating partitions from disk utility which results in error: , Error creating partition: helper exited with exit code 1: In part_add_partition: device_file=/dev/sda, start=51211402240, size=1923000000, type=0x83 Entering MS-DOS parser (offset=0, size=640135028736) MSDOS_MAGIC found looking at part 0 (offset 1048576, size 104857600, type 0x07) new part entry looking at part 1 (offset 105906176, size 51104448512, type 0x07) new part entry looking at part 2 (offset 51211402240, size 588923274240, type 0x05) Entering MS-DOS extended parser (offset=51211402240, size=588923274240) readfrom = 51211402240 MSDOS_MAGIC found Exiting MS-DOS extended parser looking at part 3 (offset 290134687744, size 349999988736, type 0x83) new part entry Exiting MS-DOS parser MSDOS partition table detected containing partition table scheme = 1 got it Error: Can't have overlapping partitions. ped_disk_new() failed Here's what I get when I try to install the system i.stack.imgur.com/pjlb9.png, i.stack.imgur.com/g1lXN.png P.S. It's strange that I even can't create any more partitions neither with disk-utility nor with windows 7 native tools

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• Fix bad superblock on logical partition

  - by Chris

  I was following http://www.howtoforge.com/linux_resi...xt3_partitions and when i reboot and run: root@Microknoppix:/home/knoppix# fsck -n /dev/sda7 fsck from util-linux-ng 2.17.2 e2fsck 1.41.12 (17-May-2010) fsck.ext2: Superblock invalid, trying backup blocks... fsck.ext2: Bad magic number in super-block while trying to open /dev/sda7 The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 <device> so i ran e2fsck with all the block numbers that you need (forget exactly what tool i used to find where the superblocks are hidden) no dice then i ran testdisk and had it look for the superblock, no results anyone have any ideas? fdisk -l for reference: root@Microknoppix:/home/knoppix# fdisk -l Disk /dev/sda: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x97646c29 Device Boot Start End Blocks Id System /dev/sda1 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 64 38912 312046593 f W95 Ext'd (LBA) /dev/sda5 64 326 2104320 82 Linux swap / Solaris /dev/sda6 * 327 2938 20972544 83 Linux /dev/sda7 2938 38912 288968672+ 83 Linux To be honest it looks like I lost it... Next step if that happens is to dump the partition to an image file and hope i can find or write some software to parse through the data looking for known file headers, i think.

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• unable to recover data from failed hdd

  - by Eslam Elyamany

  my hdd failing (or maybe totally dead) i've connected the hdd via USB but it doesn't appear in fdisk Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0xe9fb38fb Device Boot Start End Blocks Id System /dev/sda1 * 2048 206847 102400 7 HPFS/NTFS/exFAT /dev/sda2 206848 40959999 20376576 7 HPFS/NTFS/exFAT /dev/sda4 40962046 976771071 467904513 5 Extended Partition 4 does not start on physical sector boundary. /dev/sda5 82913280 86910975 1998848 82 Linux swap / Solaris /dev/sda6 86913024 394113023 153600000 7 HPFS/NTFS/exFAT /dev/sda7 40962048 82913279 20975616 83 Linux /dev/sda8 394122708 976768064 291322678+ 7 HPFS/NTFS/exFAT Partition 8 does not start on physical sector boundary. no sdc appears here , BUT it's appears on /dev/ rootghost-lap:/home/ghost# ls /dev/sd* /dev/sda /dev/sda2 /dev/sda5 /dev/sda8 /dev/sdb /dev/sdc1 /dev/sdc2 /dev/sdc6 /dev/sdc8 /dev/sda1 /dev/sda4 /dev/sda6 /dev/sda9 /dev/sdc /dev/sdc10 /dev/sdc5 /dev/sdc7 /dev/sdc9 also it appears in proc Code: rootghost-lap:/home/ghost# cat /proc/partitions major minor #blocks name 8 0 488386584 sda 8 1 102400 sda1 8 2 20376576 sda2 8 4 1 sda4 8 5 1998848 sda5 8 6 153600000 sda6 8 8 291322678 sda8 8 9 20975616 sda9 11 0 1048575 sr0 11 1 99136 sr1 8 32 244198583 sdc 8 33 14651248 sdc1 8 34 1 sdc2 8 37 15380480 sdc5 8 38 4153344 sdc6 8 39 48829536 sdc7 8 40 48829536 sdc8 8 41 110374551 sdc9 8 42 1975963 sdc10 and dmesg : [10604.777168] end_request: I/O error, dev sdc, sector 1 [10604.817238] sd 26:0:0:0: [sdc] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE [10604.817243] sd 26:0:0:0: [sdc] Sense Key : Aborted Command [current] [10604.817248] sd 26:0:0:0: [sdc] Add. Sense: No additional sense information [10604.817253] sd 26:0:0:0: [sdc] CDB: Read(10): 28 00 00 00 00 02 00 00 06 00 ok now , let's see what i've tried testdisk to check for partitions -- failed dd to copy data from /dev/sdcX -- provide strange output size for example /dev/sdc1 is about 15G , the output for dd is 62G+ so i had to cancle it safecopy successfully made an image for partitons , but can't fix images, can't mount it, can't do any thing with it and some other tools i've tried and all failed , so any idea ?

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• Accidentally dd'ed an image to wrong drive / overwrote partition table + NTFS partition start

  - by Kento Locatelli

  I screwed up and set the wrong output for dd when trying to copy a freenas iso, overwriting the wrong external hard drive. Ironically, I was trying to setup a freenas server for data backup... External drive is only used for data storage, system is entirely intact Drive had a single NTFS partition filing the entire device (2TB WD elements) Drive originally had an MBR partition table. Drive now shows as having a GPT, presumably from the freenas image. Drive was mounted at the time, with maybe a couple kB of data written/read after running dd Drive is just a few months old and healthy (regular SMART / fs checks) I have not reboot the OS (crunchbang) /proc/partition still holds the correct information (and has been stored) Have dd's output (records in / out / bytes) testdrive did not find any partitions on quick or deep search running photorec to recover the more important data (a couple recent plaintext files that hadn't been backed up yet). Vast majority of disk content ( 80%) is unnecessary media files. My current plan is to let photorec do it's thing, then recreate the mbr with gparted and use cfdisk to create another NTFS partition using the sector information from /sys/block/.../. Is that a good course of action (that is, a chance of success)? Or anything else I should try first? Possibly relevant information: dd if=FreeNAS-8.0.4-RELEASE-p3-x86.iso of=/dev/sdc: 194568+0 records in 194568+0 records out 99618816 bytes (100 MB) copied grep . /sys/block/sdc/sdc*/{start,size}: /sys/block/sdc/sdc1/start:2048 /sys/block/sdc/sdc1/size:3907022848 cat /proc/partitions: major minor #blocks name ** Snipped ** 8 32 1953512448 sdc 8 33 1953511424 sdc1 current fdisk -l output: WARNING: GPT (GUID Partition Table) detected on '/dev/sdc'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sdc: 2000.4 GB, 2000396746752 bytes 255 heads, 63 sectors/track, 243201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/sdc doesn't contain a valid partition table

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• Updated my WAMP Server and MySQL is eating up 580mB of memory

  - by Jon

  I updated my dev-box's WAMPSERVER, and along with updating PHP and Apache, MySQL updated to '5.6.12'. After doing that, I copied the data folder from my old (5.1.36) install to the new one and now MySQL takes up 580mB which is way too much, since I'm the only person using it (Locally) and there are only 20 or so databases on it, none of which have 'memory' tables. How can I get this down to a decent amount? My my.ini: # For advice on how to change settings please see # http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html # *** DO NOT EDIT THIS FILE. It's a template which will be copied to the # *** default location during install, and will be replaced if you # *** upgrade to a newer version of MySQL. [mysqld] # Remove leading # and set to the amount of RAM for the most important data # cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%. # innodb_buffer_pool_size = 128M # Remove leading # to turn on a very important data integrity option: logging # changes to the binary log between backups. # log_bin # These are commonly set, remove the # and set as required. # basedir = ..... # datadir = ..... # port = ..... # server_id = ..... # Remove leading # to set options mainly useful for reporting servers. # The server defaults are faster for transactions and fast SELECTs. # Adjust sizes as needed, experiment to find the optimal values. # join_buffer_size = 128M # sort_buffer_size = 2M # read_rnd_buffer_size = 2M sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES Database info: Storage Engine Data Size Index Size Total Size InnoDB 48.00 KB 0.00 B 48.00 KB MEMORY 0.00 B 0.00 B 0.00 B MyISAM 163.64 MB 122.49 MB 286.13 MB Total 163.69 MB 122.49 MB 286.18 MB

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• sudo fdisk in a live session does not show all hard drives

  - by cornbread

  I am having Grub2 issues in my Ubuntu 10.04 dual boot, 2 hard drive system. So I am attempting to follow the standard grub2 reinstallation guide (cant post link because of spam filters allowing only one... ?_?) Don't know if this is the root of my problem, but my speedy internal HD with my OS on it is not showing up anywhere in a live session. Not in nautilus, behind fdisk.... no where. When I can get the main system to boot, there is no issue seeing all available partitions. But the live session sees only the 1TB internal media/backup hard drive. I need access to the other hard drive and it's partitions to finish the grub2 re-installation but I am not sure anymore that is the underlying issue. Anyone have experience with this? The issue I have identified as a grub2 issue is fully described here. SandPvvr describes it exactly. Some notes: I do not see the grub2 menu for my os's holding down the shift key after my bios screen works maybe 10% of the time Not related to reinstalling a windows os. havent been touched in a year do some web development. issue may have started when I was playing with ruby and django. not sure on this. Could a dev environment do this? fdisk in live session ubuntu@ubuntu:~$ sudo fdisk -l Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0001d518 Device Boot Start End Blocks Id System /dev/sdb2 1 121601 976759939 5 Extended /dev/sdb5 487 110765 885816036 83 Linux /dev/sdb6 110766 121601 87040138+ b W95 FAT32 /dev/sdb7 1 486 3903700+ 82 Linux swap / Solaris Partition table entries are not in disk order

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• How Do I Stop NFS Clients from Using All of the NFS Server's Resources?

  - by Ken S.

  I have a v4 NFS server running on Ubuntu 12.04LTS. It is the main repository for the web assets that four external nginx webservers mount to serve up to site visitors. These client servers connect to it via a read-only mount. Each of these RO servers has this displayed when I check the mounts: 10.0.0.90:/assets on /var/www/assets type nfs4 (ro,addr=10.0.0.90,clientaddr=0.0.0.0) The NFS master's /etc/exports file contains entries like this for each server: /mnt/lvm-ext4 10.0.0.40(ro,fsid=0,insecure,no_subtree_check,async) The problem that I'm seeing is that these clients are eventually utilizing all the RAM on the NFS server and causing it to crash. If I do a watch free -m I can watch the used memory creep up until it's used and then see the free buffers/cache entry creep down to near zero before the server eventually locks up requiring a reboot. There is some sort of memory leak somewhere that is causing this, and the optimal solution would be to find it and fix it, but in the meantime I need to find a way to have the NFS server protect itself from connected clients using all it's RAM. There must be some sort of setting that limits the resources the clients can use, but I can't seem to find it. I've tried adjusting the values for rsize and wsize but they don't seem to help or be related. Thanks for any tips.

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• overriding default scheduler for blkio requests in cgroups

  - by Aamir Mushtaq

  I am trying to optimize a set of servers that have to reside on single machine. i.e. i can have multiple application server, a DB server and of course a samba server as well in same instance. Now I was looking into several optimizing options available to me. In my quest, i did my tuning of the network stack. coming to the CPU, MEMORY and the BLKIO tweaks, i am using CGROUPS. The problem i am facing is that for enhanced performance in the nature of the applications that i am running, the CFQ Scheduler that is implemented for the BLKIO subsystem is not optimal. I was looking more for a Deadline Scheduler because that will serve my purpose well. My question is whether it is possible for us to change the scheduler in the kernel compilation itself for the BLKIO to Deadline and it will reflect in my usage of [CGROUP hierarchies][3]? Since when running the service cgconf, a new fs is mounted and i dont want it to revert to CFQ scheduler. I also welcome any suggestions that will enable me to have more control over my resources.

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• "A disk read error occurred" after choosing to boot into Windows XP from GRUB

  - by kellogs

  "A disk read error occurred" appears on screen after choosing to boot into Windows XP from GRUB. [root@localhost linux]# fdisk -lu Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x48424841 Device Boot Start End Blocks Id System /dev/sda1 63 204214271 102107104+ 7 HPFS/NTFS Partition 1 does not end on cylinder boundary. /dev/sda2 204214272 255606783 25696256 af HFS / HFS+ Partition 2 does not end on cylinder boundary. /dev/sda3 255606784 276488191 10440704 c W95 FAT32 (LBA) Partition 3 does not end on cylinder boundary. /dev/sda4 276490179 312576704 18043263 5 Extended /dev/sda5 * 276490240 286709759 5109760 83 Linux /dev/sda6 286712118 310488254 11888068+ b W95 FAT32 /dev/sda7 310488318 312576704 1044193+ 82 Linux swap / Solaris Here, sda is a 160GB hard disk with quite a few partitions and 3 OSes installed. I am able to boot into Linux and Mac OS fine, but not into Windows anymore. The Windows system is located on /dev/sda1. I cannot recall how exactly have I used testdisk but it once said: Disk /dev/sda - 160 GB / 149 GiB - CHS 19458 255 63 The harddisk (160 GB / 149 GiB) seems too small! (< 169 GB / 157 GiB) Check the harddisk size: HD jumper settings, BIOS detection... So far I have tried to "fixboot" and "chkdsk" from a recovery console on the affected windows partition (/dev/sda1), the plug off power cord for 15 seconds trick, reinstalling GRUB, repairing the MFT and boot sector of the affected partition via testdisk, what next please? Thank you!

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• Getting access to physical drives in ESXi v5.5 installation on Dell PowerEdge R710 with PERC 6/i

  - by Big-Blue

  I've acquired a Dell PowerEdge R710 server a few days ago, which includes a PERC 6/i RAID controller. The server is now fitted with a SATA SSD, one SAS drive and four SATA HDD's, all of which I would like to be passed through to ESXi in an "as-is" state, without creating any logical drives in the RAID controller. Now, the ESXi v5.5 installation image I grabbed from the Dell homepage starts just fine but only lists the logical drives and connected flash drives as possible installation targets, not any of the physical drives. If I create a small logical drive on my SSD (which the PERC 6/i detects as SATA-SSD type), the ESXi install wizard lists the SSD value on that drive as false; which is far from optimal. I have also tried disabling the RAID controller entirely in the setup, but that also did not help. Everything that should enable passthrough is enabled in BIOS, but that shouldn't be a concern at this early stage of the ESXi installation. How would I be able to install ESXi v5.5 to a part of my SSD that is connected to the storage controller, while giving it entire physical access to the disk (to allow for SMART values to be read etc.)?

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• High speed network configuration

  - by Peter M

  Sorry if this seems to be a stupid question, I'm not sure how to specify what I want to know when checking google. I will have 2 or 3 devices pumping out data on a 100Base-T port. The combined data rate of all devices is about 15KB/S which exceeds the optimal 100Base-T channel capacity (12KB/S), but well within the realms of a 1000Base-T connection. Each device will be sending a burst of data in the form of an FTP transfer to a common, single host computer in a sequential manner ie: Device A establishes FTP connection and transfers data Device B establishes FTP connection and transfers data Device C establishes FTP connection and transfers data It may be that the A&B, B&C and C&A transfers overlap in the time domain to some extent. There will be minimal traffic going back from the computer to each device (in general what ever is needed to support the FTP transfers), and the network will be dedicated to transferring data between these devices and the host computer. Is it possible to use a switch to combine the multiple incoming 100Base-T streams into a single outgoing 1000Base-T stream? if so what features in a switch should I be looking for? Or would it be better to have 3 physical point-to-point 100Base-T dedicated connections between each device and the host computer? (thus having at least 3 physical Ethernet interfaces on that computer) Note that I can't change the interface on the devices, but I am free to choose the network and host computer configuration. Thanks for you help Peter

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• How to prevent asymmetric routing with multiple eBGP routers?

  - by Andy Shinn

  I have 2 routers announcing a /22 subnet to different providers (one providers connects to each of the 2 routers). I have split the /22 in two /23 to announce one /23 on each of the routers plus the /22 (the providers will take the more specific route). This allows me to fail over and keep traffic inside the /23 in and out the same provider. What are other ways in which I could announce just the /22 with both routers and have packets from servers on the network behind the routers go back out the same router in which they came in from? EDIT: The main problem I come across, which end users and clients complain about the most, is that the least hop route is sometimes not the "optimal" route. In my case, I know that Provider B may have better latency to X nation. But when packets come in from provider B, they may go out Provider A or provider B. The reverse is also true. If I send a packet to X nation out provider A, even though it may have more hops back, the packet will likely come in from Provider B (which may have higher latency, packet loss, etc. to this nation)

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• Corrupted NTFS Drive showing multiple unallocated partitions

  - by volting

  My external hdd with a single NTFS partition was accidentaly plugged out (kids!)... and is now corrupted. Iv tried running ntfsfix - with no luck - output below.. When I look at the disk under disk management in Windows 7 it shows up as having 5 partitions 2 of which are unallocated - none have drive letters and it is not possible to set any (that option and most others are greyed out) - so I can't run chkdsk /f Iv tried using Minitool partition wizard which was mentioned as a solution to another similar question here. It showed the whole drive as one partition, but as unallocated, and the option -- "Check File System" was greyout. Is there anything else I could try ? Output of fdisk -l Disk /dev/sdb: 1500.3 GB, 1500299395072 bytes 255 heads, 63 sectors/track, 182401 cylinders, total 2930272256 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytest I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x69205244 This doesn't look like a partition table Probably you selected the wrong device. Device Boot Start End Blocks Id System /dev/sdb1 ? 218129509 1920119918 850995205 72 Unknown /dev/sdb2 ? 729050177 1273024900 271987362 74 Unknown /dev/sdb3 ? 168653938 168653938 0 65 Novell Netware 386 /dev/sdb4 2692939776 2692991410 25817+ 0 Empty Partition table entries are not in disk order Output of ntfsfix me@vaio:/dev$ sudo ntfsfix /dev/sdb Mounting volume... ntfs_mst_post_read_fixup_warn: magic: 0xffffffff size: 1024 usa_ofs: 65535 usa_count: 65534: Invalid argument Record 0 has no FILE magic (0xffffffff) Failed to load $MFT: Input/output error FAILED Attempting to correct errors... ntfs_mst_post_read_fixup_warn: magic: 0xffffffff size: 1024 usa_ofs: 65535 usa_count: 65534: Invalid argument Record 0 has no FILE magic (0xffffffff) Failed to load $MFT: Input/output error FAILED Failed to startup volume: Input/output error Checking for self-located MFT segment... ntfs_mst_post_read_fixup_warn: magic: 0xffffffff size: 1024 usa_ofs: 65535 usa_count: 65534: Invalid argument OK ntfs_mst_post_read_fixup_warn: magic: 0xffffffff size: 1024 usa_ofs: 65535 usa_count: 65534: Invalid argument Record 0 has no FILE magic (0xffffffff) Failed to load $MFT: Input/output error Volume is corrupt. You should run chkdsk. Options available with MiniTool: Related questions: How to fix a damaged/corrupted NTFS filesystem/partition without losing the data on it? Repair corrupted NTFS File System

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• Messed up partitions... system will not boot!

  - by someguy

  I did a really dumb thing. cfdisk threw an error at me saying "FATAL ERROR: Bad primary partition 3: Partition ends in the final partial cylinder", so I installed Partition Table Doctor to see if I could fix the problem. When the program started up, it told me there were problems with my partitions, and asked if I wanted them fixed (cannot remember real message, but I believe it had something to do with the cylinder boundaries), so, blindly, without thinking of the consequences, I did. Now, my system will not boot. I tried booting from the Windows 7 installation CD. I went to install a fresh copy, but it said that "No drives were found". I then opened up diskpart. According to diskpart, there is only one partition, containing one volume, assigned the letter "C". Before, I had four partitions! It is also saying that the file system is RAW. Is there any way I can fix this? I have important data that I do not want to lose. Later on... I tried fdisk with the option -l, which lists the partition table(s), and this is what I got: Ignoring extra extended partition 4 Disk /dev/sda: 250.1 GB, 250059350016 bytes 255 heads, 64 sectors/track, 30401 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x163df116 Device Boot Start End Blocks Id System /dev/sda1 6 18 102400 7 HPFS/NTFS Partition 1 does not end on cylinder boundary. /dev/sda2 18 7851 62918572+ 7 HPFS/NTFS /dev/sda3 13073 30402 139196416 f W95 Ext'd (LBA) /dev/sda3 13073 30402 139196416 f W95 Ext'd (LBA) /dev/sda3 13073 30403 139203193 7 HPFS/NTFS I don't know if this will help, but it's extra information, at least. Also, this is how I had my partitions: 40MB (Unallocated) 100MB (System Reserved) 60GB (Windows, C:) 40GB (Was reserved for secondary OS) ~132GB (Home, E:)

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• dd on entire disk, but do not want empty portion

  - by Jonathan Henson

  I have a disk, say /dev/sda. Here is fdisk -l: Disk /dev/sda: 64.0 GB, 64023257088 bytes 255 heads, 63 sectors/track, 7783 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0000e4b5 Device Boot Start End Blocks Id System /dev/sda1 * 1 27 209920 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 27 525 4000768 5 Extended Partition 2 does not end on cylinder boundary. /dev/sda5 27 353 2621440 83 Linux /dev/sda6 353 405 416768 83 Linux /dev/sda7 405 490 675840 83 Linux /dev/sda8 490 525 282624 83 Linux I need to make an image to store on our file server for use in flashing other devices we are manufacturing so I only want the used space (only about 4gb). I want to keep the mbr etc... as this device should be boot ready as soon as the copy is finished. Any ideas? I previously had been using dd if=/dev/sda of=[//fileserver/file], but at that time, my master copy was on a 4gb flash ide.

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• a disk read error occurred [closed]

  - by kellogs

  Hi, ¨a disk read error occurred¨ appears on screen after choosing to boot into Windows XP from GRUB. [root@localhost linux]# fdisk -lu Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x48424841 Device Boot Start End Blocks Id System /dev/sda1 63 204214271 102107104+ 7 HPFS/NTFS Partition 1 does not end on cylinder boundary. /dev/sda2 204214272 255606783 25696256 af HFS / HFS+ Partition 2 does not end on cylinder boundary. /dev/sda3 255606784 276488191 10440704 c W95 FAT32 (LBA) Partition 3 does not end on cylinder boundary. /dev/sda4 276490179 312576704 18043263 5 Extended /dev/sda5 * 276490240 286709759 5109760 83 Linux /dev/sda6 286712118 310488254 11888068+ b W95 FAT32 /dev/sda7 310488318 312576704 1044193+ 82 Linux swap / Solaris sda is a 160GB hard disk with quite a few partitions and 3 OSes installed. I am able to boot into Linux and Mac OS fine, but not into Windows anymore. The Windows system is located on /dev/sda1. I can not recall how exactly have I used testdisk but it once said that ¨The harddisk /dev/sda (160GB / 149 GB) seems too small! (< 172GB / 157GB)¨ or something simillar. So far I have tried to ¨fixboot¨ and ¨chkdsk¨ from a recovery console on the affected windows partition (/dev/sda1), the plug off power cord for 15 seconds trick, reinstalling GRUB, repairing the MFT and boot sector of the affected partition via testdisk, what next please ? Thank you!

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• sys.dm_exec_query_stats interaction with recompilation

  - by Sam Saffron

  We use sys.dm_exec_query_stats to track down slow queries and queries that are IO offenders. This works great, we get a lot of very insightful stats. It is clear this is not as accurate as running a profiler trace, as you have no idea when SQL Server will decide to chuck out a an execution plan. We have quite a few queries where the wrong execution plan is cached. For example queries like the following: SELECT TOP 30 a.Id FROM Posts a JOIN Posts q ON q.Id = a.ParentId JOIN PostTags pt ON q.Id = pt.PostId WHERE a.PostTypeId = 2 AND a.DeletionDate IS NULL AND a.CommunityOwnedDate IS NULL AND a.CreationDate @date AND LEN(a.Body) 300 AND pt.Tag = @tag AND a.Score 0 ORDER BY a.Score DESC The problem is that the ideal plan really depends on the date selected (screenshot of ideal plan): However if the wrong plan is cached, it totally chokes when the date range is big: (notice the big fat lines) To overcome this we were recommended to use either OPTION (OPTIMIZE FOR UNKNOWN) or OPTION (RECOMPILE) OPTIMIZE FOR UNKNOWN results in a slightly better plan, which is far from optimal. Executions are tracked in sys.dm_exec_query_stats. RECOMPILE results in the best plan being chosen, however no execution counts and stats are tracked in sys.dm_exec_query_stats. Is there another DMV we could use to track stats on queries with OPTION (RECOMPILE)? Is this behavior by-design? Is there another way we can for recompilation while keeping stats tracked in sys.dm_exec_query_stats? Note: the framework will always execute parameterized queries using sp_executesql

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• What format should I convert my iTunes Videos to?

  - by Aequitarum Custos

  Recently got Daniusoft Media Converter, and was about to strip the DRM off my iTunes library, then I found I had a huge decision to make. Converting my music seems obvious, to MP3, however the video formats, I'm at a loss on. It has "optimized" formats for all types of video players such as iPhone, Zune, Droid (which I own), and just a huge list! I bought several seasons of House and a few movies, though I don't know which format would be optimal to not lose quality. While I love my Droid, I have no intention on watching full episodes or movies on it, and I have a feeling that would reduce quality. One of the options sections is HD Video, and it has HD MPEG-4 Video (*.mp4). That one seems like it would be the best format to convert to without losing quality, but again, I'm unsure. Has anyone used this software, or have general expertise in video formats to give a recommendation on what file format I should convert my videos to? Format requirements: No loss in quality Portability would be ideal (as in, will play on my Windows and potentially MAC, and streamable to a bigscreen).

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