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  • Problem restoring from tar backup: why are there /dev/disk/by-id/ symlinks and how can I avoid them?

    - by SK.
    Hello, I'm trying to make a bare-bone backup system with the most basic tools available on openSUSE 11.3 (in this case: bash, fdisk, tar & grub legacy) Here's the workflow for my scripts: backup.sh: (Run from external system, e.g. LiveCD) make an fdisk script ($fscript) from fdisk -l's output [works] mount the partitions from the system's fstab [works] tar the crucial stuff in file.tgz [works] restore.sh: (Run from external system, e.g. LiveCD) run fdisk $dest < $fscript to restore partitioning [works] format and mount partitions from system's fstab [fails] extract from file.tgz [works when mounting manually] restore grub [fails] I have recently noticed that openSUSE (though I'm sure it has nothing to do with the distro) has different output in /etc/fstab and /boot/grub/menu.lst, more precisely the partition name is for example "/dev/disk/by-id/numbers-brandname-morenumbers-part2" instead of "/dev/sda2" -- but it basically is a simple symlink. My questions about this: what is the point of such symlinks, especially if we're restoring on a different disk? is there a way to cleanly prevent the creation of those symlinks and use the "true" /dev/sdx everywhere instead? if the previous is no, do you know a way to replace those symlinks on the fly in a text file? I tried this script but only works if the file starts with the symlink description (case of fstab, not menu.lst): ### search and replace /dev/disk/by-id/... to /dev/sdx while read oldVolume rest; do # get first element, ignore rest of line if [[ "$oldVolume" =~ ^/dev/disk/by-id/.*(-part[0-9]*$)? ]]; then newVolume=$(readlink $oldVolume) # replace pointer by pointee, returns "../../sdx" echo /dev/${newVolume##*/} $rest >> TMP # format to "/dev/sdx", write line else echo $oldVolume $rest >> TMP # nothing to do fi done < $file mv -f TMP $file # save changes I've had trouble finding a solution to this on google so I was hoping some of the members here could help me. Thank you.

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  • Should I partition a 1TB Hard Disk whose primary use is media storage?

    - by Senthil
    I am going to get a 1TB hard disk. I will be storing 1080p or 720p movies, high-bitrate music and pictures in it. I use my PC 90% of the time only to play/listen/see those. I am running out of space in my current HD so I am getting another one. My specs are 2.7GHz Dual Core, 512MB GeForce 9400GT, 2GB DDR2 RAM and all the proper matroska codecs/players. I guess that is enough to play 1080p movies withough a glitch, given an ideal hard disk. I've read about proper partitioning giving performance improvement etc.. I don't want my hard disk to be the bottleneck. Can someone tell me whether I should partition my 1TB hard disk into many drives? If I should, what is the ideal size of each partition? Smooth playing of movies is very important to me. Once I start filling up the disk, there is no turning back. So I want to get it right before I start. Thanks.

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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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  • Should I partition my main table with 2 millions rows?

    - by domribaut
    Hi, I am a developer and would need some DBA-advices. We are starting to get performance problem with a MSSQL2005 database. The visible effects of the incidents is mainly CPU-hog on the server but operations reported that it was also draining resources from the SAN (not always). the main source of issues is for sure in some application but I am wondering if we should partition some of the main tables anyway in order to relax the I/O pressure. The base is about 60GB in one file. The main table (order) has 2.1 Million rows with a 215 colones (but none is huge). We have an integer as PK so it should be OK to define a partition function. Will we win something with partitioning? will partition indexes buy us something? Here are some more facts about the DB and the table database_name database_size unallocated space My_base 57173.06 MB 79.74 MB reserved data index_size unused 29 444 808 KB 26 577 320 KB 2 845 232 KB 22 256 KB name rows reserved data index_size unused Order 2 097 626 4 403 832 KB 2 756 064 KB 1 646 080 KB 1688 KB Thanks for any advice Dom

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  • Will these instructions work when turning of journaling on an ext4 SSD?

    - by snowlord
    I have an Acer Aspire One with an SSD for storage. I recently installed Ubuntu on it and chose ext4 for my filesystem. Then I read that journaling on an SSD isn't the best idea, so I will try to disable journaling and I have found these intstructions (from http://fenidik.blogspot.com/2010/03/ext4-disable-journal.html): # Create ext4 fs on /dev/sda10 disk mkfs.ext4 /dev/sda10 # Enable writeback mode. This mode will typically provide the best ext4 performance. tune2fs -o journal_data_writeback /dev/sda10 # Delete has_journal option tune2fs -O ^has_journal /dev/sda10 # Required fsck e2fsck -f /dev/sda10 # Check fs options dumpe2fs /dev/sda10 |more For more performance add fstab opions: data=writeback,noatime,nodiratime i.e: /dev/sda10 /opt ext4 defaults,data=writeback,noatime,nodiratime 0 0 I will use them on my boot partition. Are there any particularly bad parts here, or are there any missing steps? Will my boot partition be fit for being on an SSD after this? Or should I consider switching to ext2, or even reinstall it all and choose ext2 at partitioning time (I'd rather not though, since I've configured quite some stuff already)?

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  • Device CAL, User Cal or Processor license needed for SQL 2008 (architecture explained inside)?

    - by nycgags
    So we have a number of servers in the Amazon cloud running SQL Server Standard edition to aggregate data. For that purpose we are fine, the licensing is handled by our contract with Amazon, no problem there. For the beefier work, we want to install Enterprise Edition (EE) on our servers processing raw data so that we can take advantage of table partitioning. We currently have 3 servers aggregating data from about 40 node servers, all 43 of these servers are running standard edition which is fine. We also have 4 servers running standard processing the raw data, but I think we can get away with 2 (for redundancy) running Enterprise Edition. We have 2-3 dba's that access these DW servers for maintenance (using the same windows login via remote desktop). So visually: 40 -- 3 -- [2] -- 2 -- 1 nodes -- aggregators -- raw (which we want to run EE) -- calculators -- datawarehouse Nodes PUSH to aggregators, Raws PULL from aggregators, Calculators PULL from Raw, Calculators PUSH to datwarehouse I am specifying the push vs. pull in case that changes how the # of licenses is calculated. Q1) how many device (or user) CAL's do we need? Q2) do I need to speak with someone from MSFT to find out if it is ok to install in the Amazon Cloud (Amazon said we need to verify it is ok in our license terms)? Q3) what happens if another device tries to access a server with the limited number of device CAL's? Q4) Are the device CAL's simultaneous number of devices or total? Q5) Do Device and User CAL's cost the same or is there a difference? Q6) Would we need to buy a processor license (we are hoping not to)?

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  • Can't Install Win2k8 On KVM - Classic 0x80070013 error

    - by javano
    I am trying to install Win2k8 Std as a KVM guest on Debian Squeeze. As you can see from these screen shots; No drives are detected (I have blanked out a 20GB image for testing) - screenshot1 I am using this driver CD: - screenshot2 I have signed the Win7 driver (I assume this was the most appropriate one?) - screenshot3 I can now see an unpartitioned drive - screenshot4 But I can't create a new partition on here, getting the error code 0x80070013 - screenshot5 I have had this error code before but only on a physical server. If I remember correctly it was complaining because the disks were partitioned as GPT (because it was a server that was being re-purposed) so repartitioning with an MS-DOS table fixed that. This is a blank disk image though. What is wrong here, and how can I correct this? Thank you. UPDATE I have booted the VM with a Gparted-Live disk and formatted this volume with an MS-DOS partitioning scheme, and a single 20GB NTFS file system. Now when I boot the Win2k8 CD, load my drivers, I get a different error. As you can see at the bottom of screenshot6 "Windows cannot be installed on this hard drive space. Windows must be installed to a partition formatted as NTFS". Clicking format produces the error (0x80004005) on the screen, so I think this is still a driver issue because Windows can see the drive but not interact with it properly. Is that insane thinking?

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  • Make UEFI, GPT, Bootloader, SSD, USB, Linux and Windows work together

    - by user129552
    I like to use the latest hardware and the latest software; thus I have a Laptop (Lenovo X220) with UEFI instead of BIOS an SSD instead of an HDD GPT partitioning scheme instead of MBR USB to boot from instead of optical disks. I need to use both Windows and Linux. I tried to make them work alongside, but I didn't succeed. Most Linux distribution isos don't even really work on UEFI systems booted from USB. (Not even the self-claimed cutting-edge Fedora. I also tried Linux Mint Debian Edition and Sabayon Linux (according to this guide) which did not work. Only Ubuntu worked for me. I first installed Windows 8 which created sda1: Recovery, sda2: EFI system, sda3: msftres, sda4: NTFS Windows. Windows worked without a problem. I then created sda5: linux-swap and installed Ubuntu into sda6: btrfs. After rebooting, I was not presented GRUB2 as expected, but instead my system just booted into Ubuntu. I could no longer access Windows. After fixing dpkg in btrfs Ubuntu, I followed the Ubuntu documentation on UEFI booting. The result left me with a broken GRUB2, but interestingly, when I wanted to select the device to boot from, I was not only presented the internal SSD, an attached USB device, or LAN, but also Grub2 (broken), Ubuntu and Windows. The result is not very satisfying to me. What would I have to do to fix everything? Or differently asked, what operating system should I install at what point given my possibilities and requirements, so that I have a working bootloader in my UEFI GPT system which presents me a working Linux and Windows.

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  • How to restart boot Windows 7 after upgrading to a SSHD on SONY VAIO with recovery discs?

    - by Boris Okun
    The original HDD on my Sony VAIO still works, but has a damaged sector 0 and I was constantly prompted to replace the HDD because of the imminent failure. I created recovery discs as instructed, used a USB external HDD for complete back up (including Windows image back up). After installing the SSHD and using recovery discs to upload Windows and boot, I am getting the Windows welcome screen. Right after that, I'm getting the following message: Windows couldn't complete the installation. To install Windows on this computer, restart the installation. I have tried repeating the process many times all kinds of different ways and I still receive the same message. Also, when I tried to change to partitioning as the other option offered, I get the message: Windows Setup could not configure Windows to run on this computer's hardware. All troubleshooting for hardware and PCU came out solid. I tried to load the image back up from the external drive, but can't load the driver. The computer doesn't see it. Does anyone have a clue or has encountered something similar?

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  • Removing a device in "removed" state from Linux software RAID array

    - by Sahasranaman MS
    My workstation has two disks(/dev/sd[ab]), both with similar partitioning. /dev/sdb failed, and cat /proc/mdstat stopped showing the second sdb partition. I ran mdadm --fail and mdadm --remove for all partitions from the failed disk on the arrays that use them, although all such commands failed with mdadm: set device faulty failed for /dev/sdb2: No such device mdadm: hot remove failed for /dev/sdb2: No such device or address Then I hot swapped the failed disk, partitioned the new disk and added the partitions to the respective arrays. All arrays got rebuilt properly except one, because in /dev/md2, the failed disk doesn't seem to have been removed from the array properly. Because of this, the new partition keeps getting added as a spare to the partition, and its status remains degraded. Here's what mdadm --detail /dev/md2 shows: [root@ldmohanr ~]# mdadm --detail /dev/md2 /dev/md2: Version : 1.1 Creation Time : Tue Dec 27 22:55:14 2011 Raid Level : raid1 Array Size : 52427708 (50.00 GiB 53.69 GB) Used Dev Size : 52427708 (50.00 GiB 53.69 GB) Raid Devices : 2 Total Devices : 2 Persistence : Superblock is persistent Intent Bitmap : Internal Update Time : Fri Nov 23 14:59:56 2012 State : active, degraded Active Devices : 1 Working Devices : 2 Failed Devices : 0 Spare Devices : 1 Name : ldmohanr.net:2 (local to host ldmohanr.net) UUID : 4483f95d:e485207a:b43c9af2:c37c6df1 Events : 5912611 Number Major Minor RaidDevice State 0 8 2 0 active sync /dev/sda2 1 0 0 1 removed 2 8 18 - spare /dev/sdb2 To remove a disk, mdadm needs a device filename, which was /dev/sdb2 originally, but that no longer refers to device number 1. I need help with removing device number 1 with 'removed' status and making /dev/sdb2 active.

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  • Kickstarting an Ubuntu Server 10.04 installation (DHCP fails)

    - by William
    I'm trying to automate the network installation of Ubuntu 10.04 LTS with an anaconda kickstart and everything seems to running except for the initial DHCP autoconfiguration. The installer attempts to configure the install via DHCP but fails on its first attempt. This brings me to a prompt where I can retry DHCP and it seems to always work on the second attempt. My issue is that this is not really automated if I have to hit retry for DHCP. Is there something I can add to the kickstart file so that it will automatically retry or better yet not fail the first time? Thanks. Kickstart: # System language lang en_US # Language modules to install langsupport en_US # System keyboard keyboard us # System mouse mouse # System timezone timezone America/New_York # Root password rootpw --iscrypted $1$unrsWyF2$B0W.k2h1roBSSFmUDsW0r/ # Initial user user --disabled # Reboot after installation reboot # Use text mode install text # Install OS instead of upgrade install # Use Web installation url --url=http://10.16.0.1/cobbler/ks_mirror/ubuntu-10.04-x86_64/ # System bootloader configuration bootloader --location=mbr # Clear the Master Boot Record zerombr yes # Partition clearing information clearpart --all --initlabel # Disk partitioning information part swap --size 512 part / --fstype ext3 --size 1 --grow # System authorization infomation auth --useshadow --enablemd5 %include /tmp/pre_install_ubuntu_network_config # Always install the server kernel. preseed --owner d-i base-installer/kernel/override-image string linux-server # Install the Ubuntu Server seed. preseed --owner tasksel tasksel/force-tasks string server # Firewall configuration firewall --disabled # Do not configure the X Window System skipx %pre wget "http://10.16.0.1/cblr/svc/op/trig/mode/pre/system/Test-D" -O /dev/null # Network information # Start pre_install_network_config generated code # Start of code to match cobbler system interfaces to physical interfaces by their mac addresses # Start eth0 # Configuring eth0 (00:1A:64:36:B1:C8) if ip -o link show | grep -i 00:1A:64:36:B1:C8 then IFNAME=$(ip -o link show | grep -i 00:1A:64:36:B1:C8 | cut -d" " -f2 | tr -d :) echo "network --device=$IFNAME --bootproto=dhcp" >> /tmp/pre_install_ubuntu_network_config fi # End pre_install_network_config generated code %packages openssh-server

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  • Is there a way to do a sector level copy/clone from one hard drive to another?

    - by irrational John
    Without going into distracting details, I'm attempting to duplicate the contents of the 500GB drive in my MacBook to another 500GB drive. But this is turning out to be an unexpected hassle because the drive contains both the OS X partition and an NTFS partition with Win 7 via Apple's Boot Camp. With the exception of Clonezilla, the tools I have looked at so far all have some limitation. The Mac tools don't want to deal with the NTFS partition. The Windows tools are totally clueless about either the HFS+ partition and/or the hybrid MBR/GPT Boot Camp partitioning. Clonezilla looked like it would do what I want but apparently I can't figure out how to use it. After doing what I thought was a sector to sector copy I found that only the NTFS partition had been migrated. The others were apparently empty. (And frankly, I'm not positive Clonezilla migrated the partition table correctly either). Note: It takes over 2 hours using SATA to read/write all sectors with these drives. So I'm not up for using trial & error to narrow in on the right combination of Clonezilla options to use. I'm beginning to think that maybe the answer is to boot Linux (probably Ubuntu) and then use some ancient BSD command. Trouble is I don't know what command (or parameters to use) in order to do a sector level copy from one drive to another. As far as I know the drives have the same number of sectors so this should be trivial. Sigh.

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  • Trying to retrieve data with a thermaltake blacX enclosure: Windows 7 believes the drive to be "uninitialized"

    - by Peeter Joot
    I have a laptop that won't boot. It appears to be a power problem ... laptop auto-turns-off within about 10 seconds of pressing the power button (with power buttons lighted temporarily and no display with or without external monitor). I've followed the dell troubleshooting guide which suggested reseating the memory modules and the hard drives, but that didn't help. Before trying to have the laptop serviced, I wanted to get some data off off the hard drive. I bought a thermaltake blacX enclosure, intending to use this to both use to retrieve the drive data with, and then later use as external storage. Following the instructions (insert cables, insert drive power on) goes fine, and Windows 7 on another laptop installs the device driver software. However, no drive letter shows up in 'Computer'. Under Computer-manage-storage I see the drive is there, and there's an option to "initialize" the drive. The Windows "initialize" dialog gives me the option to pick between "MBR" and "GPT" partitioning, which sounds like a good way to destroy the data on the drive. I'm thinking that I've purchased the wrong device for the job (or that my old drive is damaged). The old drive to recover info from is a Western Digital 500G/7200rpm SATA drive if that is relavent. Both the original laptop and the one I'm using for recovery are running Windows 7. Does anybody have experience with using a blacX enclosure to recover data off an already formatted drive?

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  • Linux: Encryption of a physical LVM volume doesn't imply encryption of its logical subvolumes?

    - by java.is.for.desktop
    Hello, everyone! I installed OpenSuse one year ago on my notebook. I created all partitions except /boot inside an LVM partition. I enabled encryption for it during setup. The system asked me a password on each boot later. Everything seemed fine... But one day I wanted to cancel the boot process and did it with SysRq REISUB. During entering this combination, the system suddenly continued to boot without any password being entered. I had no /home and no swap, but / was mounted! I checked multiple times, it was inside an "encrypted" physical LVM volume. Later I found out that OpenSuse can't encrypt / at all. There is an option to enable encryption for each logical volume, and indeed it fails for /. Later I tried Fedora. The options during partitioning were misleading by same means. I could enable "encryption" of a physical volume and each logical subvolume. With the exception that Fedora actually allowed to encrypt /. Question: What's the point of setting up "encryption" for a physical LVM volume, when it doesn't imply (real) encryption of its logical subvolumes? Did I get something wrong in this whole concept?

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  • trying to setup multiple primary partitions on ubuntu linux [migrated]

    - by JohnMerlino
    I currently have ubuntu desktop installed on a harddrive. I want to partition the harddrive so that I can reserve 30 gigs for ubuntu server and 30 gigs for ubuntu desktop. The drive has 300 gigs available. Right now I am booting from dvd drive and installing ubuntu server. I selected "Guided partitioning" and created a 30 gig primary partition of Ext4 journaling filesystem, set "yes, format it" for format partition and set bootable flag to on. I intend to use this 30 gig partition to hold ubuntu server and allow me to boot from it. Now I have two other partitions. They are both set to "logical", one is currently using 285.8 gigs and is using ext4 (when I try to set bootable flag to true, it gives a warning "You are trying to set the bootable flag on a logical partition. The bootable flag is only useful on the primary partitions"). More alarming it says "No existing file system was detected in this partition". Actually, Im thinking that this is the parittion that is supposed to be holding my current Ubuntu Desktop. And of course I want this to be bootable and be a primary partition, so I could dual boot from this and the server partition. Now the third partition is also set to logical and it is being used as swap area. My question is regarding that second partition. Its supposed to be a primary partition thats holding my existing ubuntu desktop edition. How do I switch it to primary and to make sure that its pointing to my existing desktop installation?

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  • FDE / SSD - partition and leave some unencrypted?

    - by Web Design Hero
    Just bought a used beast of a desktop pc. The system drive is setup as a Raid 0 SSD (Intel 510 SSD Drives) with 128 each. I will probably not have to many programs beyond office and maybe Adobe CS if I spring for it, I will be keeping big data on a regular hdd. My question is about setting up TrueCrypt with my configuration. I have not previously done full disk encryption, but I feel that its probably a good idea. I have done some speed tests using file containers on the hdd and the sdd with truecrypt. While there is a huge hit with the SSDs and Truecrypt, it still outperforms the hdd on its own by a good margin, so I think i will be okay for my needs with truecrypt. I have seen in a few places that they recommend partitioning the drive and leavign some of the SSD not inside truecrypt, does this really make a difference? If so, how much should I leave? Will there be any issue in the Raid0 configuration? I am not really concerned about all the wear leveling issue, rather loose data and be secure, but since I don't need all that space neccesarily, I would like to optimize my setup for security and speed.

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  • Ubuntu 12.04 can't boot after installing with software RAID 1

    - by Bill
    I've been trying to install Ubuntu with software RAID on my server and there is obviously something that I don't understand about the process. This is the guide that I followed: https://help.ubuntu.com/11.04/serverguide/advanced-installation.html I have two identical 1 TB disks in my server. I went through the initial install process and manually set up my partitions. On each disk I set up: (1) 100 MB partition for EFI boot (I didn't originally have this but added it based on a forum post I found after my original install failed to boot, I ended up with EFIboot since that was what the 'guided partitioning' decided to do) (1) 970 MB partition for / (1) 30 MB partition for swap I then created new RAID 1 disks combining the two partitions, one from each disk, such that each partition is mirrored. I then configured their usage as stated above. After saving the configuration I said yes to boot in a degraded state. The rest of the setup went normally, no errors of any kind. I saw GRUB being installed and again no errors. However, after rebooting the server I get the dreaded 'Insert boot media' and nothing happens. I loaded up the recovery disk and the mdadm configuration looks correct. md0 is my EFIBoot partition md1 is my \ partition using ext4 md2 is my swap partition Running file -s /dev/md0 doesn't indicate that GRUB is there and so I attempted to reinstall GRUB using the recovery disk. I selected the md0 disk and it appeared to install just fine. Running file -s /dev/md1 shows the error needs journal recovery, I'm not sure if that's related or not or how to fix that. Rebooting gives me the same problem, no boot media found. I've searched around the internet but can't figure out what to do next or more importantly how to troubleshoot what exactly is going wrong. Thanks!

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  • Question marks showing in ls of directory. IO errors too.

    - by jaymoo
    Has anyone seen this before? I've got a raid 5 mounted on my server and for whatever reason it started showing this: jason@box2:/mnt/raid1/cra$ ls -alh ls: cannot access e6eacc985fea729b2d5bc74078632738: Input/output error ls: cannot access 257ad35ee0b12a714530c30dccf9210f: Input/output error total 0 drwxr-xr-x 5 root root 123 2009-08-19 16:33 . drwxr-xr-x 3 root root 16 2009-08-14 17:15 .. ?????????? ? ? ? ? ? 257ad35ee0b12a714530c30dccf9210f drwxr-xr-x 3 root root 57 2009-08-19 16:58 9c89a78e93ae6738e01136db9153361b ?????????? ? ? ? ? ? e6eacc985fea729b2d5bc74078632738 The md5 strings are actual directory names and not part of the error. The question marks are odd, and any directory with a question mark throws an io error when you attempt to use/delete/etc it. I was unable to umount the drive due to "busy". Rebooting the server "fixed" it but it was throwing some raid errors on shutdown. I have configured two raid 5 arrays and both started doing this on random files. Both are using the following config: mkfs.xfs -l size=128m -d agcount=32 mount -t xfs -o noatime,logbufs=8 Nothing too fancy, but part of an optimized config for this box. We're not partitioning the drives and that was suggested as a possible issue. Could this be the culprit?

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  • Windows 7: moved system partition, need to update boot partition

    - by Actorclavilis
    So, I have a decently standard Windows7/Ubuntu dual-boot setup, and (since Ubuntu is my usual operating system) I found I needed to grow my Ubuntu partition and shrink my W7 partition. Originally, my system (500G) looked like this: W7 Boot Partition (1.5G) Ubuntu (around 240G) W7 (same as Ubuntu) (on an extended partition, all by itself) Swap (rest of disk, around 16G) Now I'm no stranger to partitioning and filesystem tools, especially GParted, which I used on a Linux boot disk. After my partition editing, the partitions are laid out the same, except the Ubuntu partition is now 407G and the W7 partition is smaller to compensate. I had supposed, based on http://www.gparted.org/faq.php, that I would be able to run the W7 install disk in recovery mode and have it deal with the rearrangement, then possibly reinstall GRUB or something. Well, now the W7 install disk doesn't even see my W7 installation. All my files are there, the NTFS is perfectly clean, no problems there, but the install disk won't notice it. (Of course, the GRUB entry works fine but the W7 boot partition (which I didn't change) refuses to boot it.) So, basically, any ideas on how to fix this? I don't especially want to rerun the entire install procedure because I'll have a bunch of programs to reinstall (never mind redoing GRUB), but I fear that might be the only option. Thanks.

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  • building a debian base image

    - by Michael
    Is there a preferred way to create base images for Debian-based customized installations? We are currently going with multistrap but although it's better than hand-crafted chroot stuff, it still has a lot of edges and corners. Is there a more reliable and less error-prone way to produce a root filesystem of a Debian installation with some additional .debs installed? (I don't want to send out a Debian installer with a preseed file though.) Addendum 1: To clarify things a bit: We are delivering some kind of software appliance to our customers. That is, a debian operating system, with some additional software packages -- both our own and third-party ones -- and some configuration changes. To ease the installation process, we have an installer that does nothing more than partitioning, copying files to the partitions and setting up grub. So it's basically an image-based installer. So we are basically running the debian installation ourselves and just distribute the already installed operating system. The question is about the installation part. I want to have that as easy and robust as possible, and of course, it should be an automated process.

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  • Windows Azure: Import/Export Hard Drives, VM ACLs, Web Sockets, Remote Debugging, Continuous Delivery, New Relic, Billing Alerts and More

    - by ScottGu
    Two weeks ago we released a giant set of improvements to Windows Azure, as well as a significant update of the Windows Azure SDK. This morning we released another massive set of enhancements to Windows Azure.  Today’s new capabilities include: Storage: Import/Export Hard Disk Drives to your Storage Accounts HDInsight: General Availability of our Hadoop Service in the cloud Virtual Machines: New VM Gallery, ACL support for VIPs Web Sites: WebSocket and Remote Debugging Support Notification Hubs: Segmented customer push notification support with tag expressions TFS & GIT: Continuous Delivery Support for Web Sites + Cloud Services Developer Analytics: New Relic support for Web Sites + Mobile Services Service Bus: Support for partitioned queues and topics Billing: New Billing Alert Service that sends emails notifications when your bill hits a threshold you define All of these improvements are now available to use immediately (note that some features are still in preview).  Below are more details about them. Storage: Import/Export Hard Disk Drives to Windows Azure I am excited to announce the preview of our new Windows Azure Import/Export Service! The Windows Azure Import/Export Service enables you to move large amounts of on-premises data into and out of your Windows Azure Storage accounts. It does this by enabling you to securely ship hard disk drives directly to our Windows Azure data centers. Once we receive the drives we’ll automatically transfer the data to or from your Windows Azure Storage account.  This enables you to import or export massive amounts of data more quickly and cost effectively (and not be constrained by available network bandwidth). Encrypted Transport Our Import/Export service provides built-in support for BitLocker disk encryption – which enables you to securely encrypt data on the hard drives before you send it, and not have to worry about it being compromised even if the disk is lost/stolen in transit (since the content on the transported hard drives is completely encrypted and you are the only one who has the key to it).  The drive preparation tool we are shipping today makes setting up bitlocker encryption on these hard drives easy. How to Import/Export your first Hard Drive of Data You can read our Getting Started Guide to learn more about how to begin using the import/export service.  You can create import and export jobs via the Windows Azure Management Portal as well as programmatically using our Server Management APIs. It is really easy to create a new import or export job using the Windows Azure Management Portal.  Simply navigate to a Windows Azure storage account, and then click the new Import/Export tab now available within it (note: if you don’t have this tab make sure to sign-up for the Import/Export preview): Then click the “Create Import Job” or “Create Export Job” commands at the bottom of it.  This will launch a wizard that easily walks you through the steps required: For more comprehensive information about Import/Export, refer to Windows Azure Storage team blog.  You can also send questions and comments to the [email protected] email address. We think you’ll find this new service makes it much easier to move data into and out of Windows Azure, and it will dramatically cut down the network bandwidth required when working on large data migration projects.  We hope you like it. HDInsight: 100% Compatible Hadoop Service in the Cloud Last week we announced the general availability release of Windows Azure HDInsight. HDInsight is a 100% compatible Hadoop service that allows you to easily provision and manage Hadoop clusters for big data processing in Windows Azure.  This release is now live in production, backed by an enterprise SLA, supported 24x7 by Microsoft Support, and is ready to use for production scenarios. HDInsight allows you to use Apache Hadoop tools, such as Pig and Hive, to process large amounts of data in Windows Azure Blob Storage. Because data is stored in Windows Azure Blob Storage, you can choose to dynamically create Hadoop clusters only when you need them, and then shut them down when they are no longer required (since you pay only for the time the Hadoop cluster instances are running this provides a super cost effective way to use them).  You can create Hadoop clusters using either the Windows Azure Management Portal (see below) or using our PowerShell and Cross Platform Command line tools: The import/export hard drive support that came out today is a perfect companion service to use with HDInsight – the combination allows you to easily ingest, process and optionally export a limitless amount of data.  We’ve also integrated HDInsight with our Business Intelligence tools, so users can leverage familiar tools like Excel in order to analyze the output of jobs.  You can find out more about how to get started with HDInsight here. Virtual Machines: VM Gallery Enhancements Today’s update of Windows Azure brings with it a new Virtual Machine gallery that you can use to create new VMs in the cloud.  You can launch the gallery by doing New->Compute->Virtual Machine->From Gallery within the Windows Azure Management Portal: The new Virtual Machine Gallery includes some nice enhancements that make it even easier to use: Search: You can now easily search and filter images using the search box in the top-right of the dialog.  For example, simply type “SQL” and we’ll filter to show those images in the gallery that contain that substring. Category Tree-view: Each month we add more built-in VM images to the gallery.  You can continue to browse these using the “All” view within the VM Gallery – or now quickly filter them using the category tree-view on the left-hand side of the dialog.  For example, by selecting “Oracle” in the tree-view you can now quickly filter to see the official Oracle supplied images. MSDN and Supported checkboxes: With today’s update we are also introducing filters that makes it easy to filter out types of images that you may not be interested in. The first checkbox is MSDN: using this filter you can exclude any image that is not part of the Windows Azure benefits for MSDN subscribers (which have highly discounted pricing - you can learn more about the MSDN pricing here). The second checkbox is Supported: this filter will exclude any image that contains prerelease software, so you can feel confident that the software you choose to deploy is fully supported by Windows Azure and our partners. Sort options: We sort gallery images by what we think customers are most interested in, but sometimes you might want to sort using different views. So we’re providing some additional sort options, like “Newest,” to customize the image list for what suits you best. Pricing information: We now provide additional pricing information about images and options on how to cost effectively run them directly within the VM Gallery. The above improvements make it even easier to use the VM Gallery and quickly create launch and run Virtual Machines in the cloud. Virtual Machines: ACL Support for VIPs A few months ago we exposed the ability to configure Access Control Lists (ACLs) for Virtual Machines using Windows PowerShell cmdlets and our Service Management API. With today’s release, you can now configure VM ACLs using the Windows Azure Management Portal as well. You can now do this by clicking the new Manage ACL command in the Endpoints tab of a virtual machine instance: This will enable you to configure an ordered list of permit and deny rules to scope the traffic that can access your VM’s network endpoints. For example, if you were on a virtual network, you could limit RDP access to a Windows Azure virtual machine to only a few computers attached to your enterprise. Or if you weren’t on a virtual network you could alternatively limit traffic from public IPs that can access your workloads: Here is the default behaviors for ACLs in Windows Azure: By default (i.e. no rules specified), all traffic is permitted. When using only Permit rules, all other traffic is denied. When using only Deny rules, all other traffic is permitted. When there is a combination of Permit and Deny rules, all other traffic is denied. Lastly, remember that configuring endpoints does not automatically configure them within the VM if it also has firewall rules enabled at the OS level.  So if you create an endpoint using the Windows Azure Management Portal, Windows PowerShell, or REST API, be sure to also configure your guest VM firewall appropriately as well. Web Sites: Web Sockets Support With today’s release you can now use Web Sockets with Windows Azure Web Sites.  This feature enables you to easily integrate real-time communication scenarios within your web based applications, and is available at no extra charge (it even works with the free tier).  Higher level programming libraries like SignalR and socket.io are also now supported with it. You can enable Web Sockets support on a web site by navigating to the Configure tab of a Web Site, and by toggling Web Sockets support to “on”: Once Web Sockets is enabled you can start to integrate some really cool scenarios into your web applications.  Check out the new SignalR documentation hub on www.asp.net to learn more about some of the awesome scenarios you can do with it. Web Sites: Remote Debugging Support The Windows Azure SDK 2.2 we released two weeks ago introduced remote debugging support for Windows Azure Cloud Services. With today’s Windows Azure release we are extending this remote debugging support to also work with Windows Azure Web Sites. With live, remote debugging support inside of Visual Studio, you are able to have more visibility than ever before into how your code is operating live in Windows Azure. It is now super easy to attach the debugger and quickly see what is going on with your application in the cloud. Remote Debugging of a Windows Azure Web Site using VS 2013 Enabling the remote debugging of a Windows Azure Web Site using VS 2013 is really easy.  Start by opening up your web application’s project within Visual Studio. Then navigate to the “Server Explorer” tab within Visual Studio, and click on the deployed web-site you want to debug that is running within Windows Azure using the Windows Azure->Web Sites node in the Server Explorer.  Then right-click and choose the “Attach Debugger” option on it: When you do this Visual Studio will remotely attach the debugger to the Web Site running within Windows Azure.  The debugger will then stop the web site’s execution when it hits any break points that you have set within your web application’s project inside Visual Studio.  For example, below I set a breakpoint on the “ViewBag.Message” assignment statement within the HomeController of the standard ASP.NET MVC project template.  When I hit refresh on the “About” page of the web site within the browser, the breakpoint was triggered and I am now able to debug the app remotely using Visual Studio: Note above how we can debug variables (including autos/watchlist/etc), as well as use the Immediate and Command Windows. In the debug session above I used the Immediate Window to explore some of the request object state, as well as to dynamically change the ViewBag.Message property.  When we click the the “Continue” button (or press F5) the app will continue execution and the Web Site will render the content back to the browser.  This makes it super easy to debug web apps remotely. Tips for Better Debugging To get the best experience while debugging, we recommend publishing your site using the Debug configuration within Visual Studio’s Web Publish dialog. This will ensure that debug symbol information is uploaded to the Web Site which will enable a richer debug experience within Visual Studio.  You can find this option on the Web Publish dialog on the Settings tab: When you ultimately deploy/run the application in production we recommend using the “Release” configuration setting – the release configuration is memory optimized and will provide the best production performance.  To learn more about diagnosing and debugging Windows Azure Web Sites read our new Troubleshooting Windows Azure Web Sites in Visual Studio guide. Notification Hubs: Segmented Push Notification support with tag expressions In August we announced the General Availability of Windows Azure Notification Hubs - a powerful Mobile Push Notifications service that makes it easy to send high volume push notifications with low latency from any mobile app back-end.  Notification hubs can be used with any mobile app back-end (including ones built using our Mobile Services capability) and can also be used with back-ends that run in the cloud as well as on-premises. Beginning with the initial release, Notification Hubs allowed developers to send personalized push notifications to both individual users as well as groups of users by interest, by associating their devices with tags representing the logical target of the notification. For example, by registering all devices of customers interested in a favorite MLB team with a corresponding tag, it is possible to broadcast one message to millions of Boston Red Sox fans and another message to millions of St. Louis Cardinals fans with a single API call respectively. New support for using tag expressions to enable advanced customer segmentation With today’s release we are adding support for even more advanced customer targeting.  You can now identify customers that you want to send push notifications to by defining rich tag expressions. With tag expressions, you can now not only broadcast notifications to Boston Red Sox fans, but take that segmenting a step farther and reach more granular segments. This opens up a variety of scenarios, for example: Offers based on multiple preferences—e.g. send a game day vegetarian special to users tagged as both a Boston Red Sox fan AND a vegetarian Push content to multiple segments in a single message—e.g. rain delay information only to users who are tagged as either a Boston Red Sox fan OR a St. Louis Cardinal fan Avoid presenting subsets of a segment with irrelevant content—e.g. season ticket availability reminder to users who are tagged as a Boston Red Sox fan but NOT also a season ticket holder To illustrate with code, consider a restaurant chain app that sends an offer related to a Red Sox vs Cardinals game for users in Boston. Devices can be tagged by your app with location tags (e.g. “Loc:Boston”) and interest tags (e.g. “Follows:RedSox”, “Follows:Cardinals”), and then a notification can be sent by your back-end to “(Follows:RedSox || Follows:Cardinals) && Loc:Boston” in order to deliver an offer to all devices in Boston that follow either the RedSox or the Cardinals. This can be done directly in your server backend send logic using the code below: var notification = new WindowsNotification(messagePayload); hub.SendNotificationAsync(notification, "(Follows:RedSox || Follows:Cardinals) && Loc:Boston"); In your expressions you can use all Boolean operators: AND (&&), OR (||), and NOT (!).  Some other cool use cases for tag expressions that are now supported include: Social: To “all my group except me” - group:id && !user:id Events: Touchdown event is sent to everybody following either team or any of the players involved in the action: Followteam:A || Followteam:B || followplayer:1 || followplayer:2 … Hours: Send notifications at specific times. E.g. Tag devices with time zone and when it is 12pm in Seattle send to: GMT8 && follows:thaifood Versions and platforms: Send a reminder to people still using your first version for Android - version:1.0 && platform:Android For help on getting started with Notification Hubs, visit the Notification Hub documentation center.  Then download the latest NuGet package (or use the Notification Hubs REST APIs directly) to start sending push notifications using tag expressions.  They are really powerful and enable a bunch of great new scenarios. TFS & GIT: Continuous Delivery Support for Web Sites + Cloud Services With today’s Windows Azure release we are making it really easy to enable continuous delivery support with Windows Azure and Team Foundation Services.  Team Foundation Services is a cloud based offering from Microsoft that provides integrated source control (with both TFS and Git support), build server, test execution, collaboration tools, and agile planning support.  It makes it really easy to setup a team project (complete with automated builds and test runners) in the cloud, and it has really rich integration with Visual Studio. With today’s Windows Azure release it is now really easy to enable continuous delivery support with both TFS and Git based repositories hosted using Team Foundation Services.  This enables a workflow where when code is checked in, built successfully on an automated build server, and all tests pass on it – I can automatically have the app deployed on Windows Azure with zero manual intervention or work required. The below screen-shots demonstrate how to quickly setup a continuous delivery workflow to Windows Azure with a Git-based ASP.NET MVC project hosted using Team Foundation Services. Enabling Continuous Delivery to Windows Azure with Team Foundation Services The project I’m going to enable continuous delivery with is a simple ASP.NET MVC project whose source code I’m hosting using Team Foundation Services.  I did this by creating a “SimpleContinuousDeploymentTest” repository there using Git – and then used the new built-in Git tooling support within Visual Studio 2013 to push the source code to it.  Below is a screen-shot of the Git repository hosted within Team Foundation Services: I can access the repository within Visual Studio 2013 and easily make commits with it (as well as branch, merge and do other tasks).  Using VS 2013 I can also setup automated builds to take place in the cloud using Team Foundation Services every time someone checks in code to the repository: The cool thing about this is that I don’t have to buy or rent my own build server – Team Foundation Services automatically maintains its own build server farm and can automatically queue up a build for me (for free) every time someone checks in code using the above settings.  This build server (and automated testing) support now works with both TFS and Git based source control repositories. Connecting a Team Foundation Services project to Windows Azure Once I have a source repository hosted in Team Foundation Services with Automated Builds and Testing set up, I can then go even further and set it up so that it will be automatically deployed to Windows Azure when a source code commit is made to the repository (assuming the Build + Tests pass).  Enabling this is now really easy.  To set this up with a Windows Azure Web Site simply use the New->Compute->Web Site->Custom Create command inside the Windows Azure Management Portal.  This will create a dialog like below.  I gave the web site a name and then made sure the “Publish from source control” checkbox was selected: When we click next we’ll be prompted for the location of the source repository.  We’ll select “Team Foundation Services”: Once we do this we’ll be prompted for our Team Foundation Services account that our source repository is hosted under (in this case my TFS account is “scottguthrie”): When we click the “Authorize Now” button we’ll be prompted to give Windows Azure permissions to connect to the Team Foundation Services account.  Once we do this we’ll be prompted to pick the source repository we want to connect to.  Starting with today’s Windows Azure release you can now connect to both TFS and Git based source repositories.  This new support allows me to connect to the “SimpleContinuousDeploymentTest” respository we created earlier: Clicking the finish button will then create the Web Site with the continuous delivery hooks setup with Team Foundation Services.  Now every time someone pushes source control to the repository in Team Foundation Services, it will kick off an automated build, run all of the unit tests in the solution , and if they pass the app will be automatically deployed to our Web Site in Windows Azure.  You can monitor the history and status of these automated deployments using the Deployments tab within the Web Site: This enables a really slick continuous delivery workflow, and enables you to build and deploy apps in a really nice way. Developer Analytics: New Relic support for Web Sites + Mobile Services With today’s Windows Azure release we are making it really easy to enable Developer Analytics and Monitoring support with both Windows Azure Web Site and Windows Azure Mobile Services.  We are partnering with New Relic, who provide a great dev analytics and app performance monitoring offering, to enable this - and we have updated the Windows Azure Management Portal to make it really easy to configure. Enabling New Relic with a Windows Azure Web Site Enabling New Relic support with a Windows Azure Web Site is now really easy.  Simply navigate to the Configure tab of a Web Site and scroll down to the “developer analytics” section that is now within it: Clicking the “add-on” button will display some additional UI.  If you don’t already have a New Relic subscription, you can click the “view windows azure store” button to obtain a subscription (note: New Relic has a perpetually free tier so you can enable it even without paying anything): Clicking the “view windows azure store” button will launch the integrated Windows Azure Store experience we have within the Windows Azure Management Portal.  You can use this to browse from a variety of great add-on services – including New Relic: Select “New Relic” within the dialog above, then click the next button, and you’ll be able to choose which type of New Relic subscription you wish to purchase.  For this demo we’ll simply select the “Free Standard Version” – which does not cost anything and can be used forever:  Once we’ve signed-up for our New Relic subscription and added it to our Windows Azure account, we can go back to the Web Site’s configuration tab and choose to use the New Relic add-on with our Windows Azure Web Site.  We can do this by simply selecting it from the “add-on” dropdown (it is automatically populated within it once we have a New Relic subscription in our account): Clicking the “Save” button will then cause the Windows Azure Management Portal to automatically populate all of the needed New Relic configuration settings to our Web Site: Deploying the New Relic Agent as part of a Web Site The final step to enable developer analytics using New Relic is to add the New Relic runtime agent to our web app.  We can do this within Visual Studio by right-clicking on our web project and selecting the “Manage NuGet Packages” context menu: This will bring up the NuGet package manager.  You can search for “New Relic” within it to find the New Relic agent.  Note that there is both a 32-bit and 64-bit edition of it – make sure to install the version that matches how your Web Site is running within Windows Azure (note: you can configure your Web Site to run in either 32-bit or 64-bit mode using the Web Site’s “Configuration” tab within the Windows Azure Management Portal): Once we install the NuGet package we are all set to go.  We’ll simply re-publish the web site again to Windows Azure and New Relic will now automatically start monitoring the application Monitoring a Web Site using New Relic Now that the application has developer analytics support with New Relic enabled, we can launch the New Relic monitoring portal to start monitoring the health of it.  We can do this by clicking on the “Add Ons” tab in the left-hand side of the Windows Azure Management Portal.  Then select the New Relic add-on we signed-up for within it.  The Windows Azure Management Portal will provide some default information about the add-on when we do this.  Clicking the “Manage” button in the tray at the bottom will launch a new browser tab and single-sign us into the New Relic monitoring portal associated with our account: When we do this a new browser tab will launch with the New Relic admin tool loaded within it: We can now see insights into how our app is performing – without having to have written a single line of monitoring code.  The New Relic service provides a ton of great built-in monitoring features allowing us to quickly see: Performance times (including browser rendering speed) for the overall site and individual pages.  You can optionally set alert thresholds to trigger if the speed does not meet a threshold you specify. Information about where in the world your customers are hitting the site from (and how performance varies by region) Details on the latency performance of external services your web apps are using (for example: SQL, Storage, Twitter, etc) Error information including call stack details for exceptions that have occurred at runtime SQL Server profiling information – including which queries executed against your database and what their performance was And a whole bunch more… The cool thing about New Relic is that you don’t need to write monitoring code within your application to get all of the above reports (plus a lot more).  The New Relic agent automatically enables the CLR profiler within applications and automatically captures the information necessary to identify these.  This makes it super easy to get started and immediately have a rich developer analytics view for your solutions with very little effort. If you haven’t tried New Relic out yet with Windows Azure I recommend you do so – I think you’ll find it helps you build even better cloud applications.  Following the above steps will help you get started and deliver you a really good application monitoring solution in only minutes. Service Bus: Support for partitioned queues and topics With today’s release, we are enabling support within Service Bus for partitioned queues and topics. Enabling partitioning enables you to achieve a higher message throughput and better availability from your queues and topics. Higher message throughput is achieved by implementing multiple message brokers for each partitioned queue and topic.  The  multiple messaging stores will also provide higher availability. You can create a partitioned queue or topic by simply checking the Enable Partitioning option in the custom create wizard for a Queue or Topic: Read this article to learn more about partitioned queues and topics and how to take advantage of them today. Billing: New Billing Alert Service Today’s Windows Azure update enables a new Billing Alert Service Preview that enables you to get proactive email notifications when your Windows Azure bill goes above a certain monetary threshold that you configure.  This makes it easier to manage your bill and avoid potential surprises at the end of the month. With the Billing Alert Service Preview, you can now create email alerts to monitor and manage your monetary credits or your current bill total.  To set up an alert first sign-up for the free Billing Alert Service Preview.  Then visit the account management page, click on a subscription you have setup, and then navigate to the new Alerts tab that is available: The alerts tab allows you to setup email alerts that will be sent automatically once a certain threshold is hit.  For example, by clicking the “add alert” button above I can setup a rule to send myself email anytime my Windows Azure bill goes above $100 for the month: The Billing Alert Service will evolve to support additional aspects of your bill as well as support multiple forms of alerts such as SMS.  Try out the new Billing Alert Service Preview today and give us feedback. Summary Today’s Windows Azure release enables a ton of great new scenarios, and makes building applications hosted in the cloud even easier. If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using all of the above features today.  Then visit the Windows Azure Developer Center to learn more about how to build apps with it. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • SQL - Rank() on a table

    - by Abhi
    create table v (mydate,value) as select to_date('20/03/2010 00','dd/mm/yyyy HH24'),98 from dual union all select to_date('20/03/2010 01','dd/mm/yyyy HH24'),124 from dual union all select to_date('20/03/2010 02','dd/mm/yyyy HH24'),140 from dual union all select to_date('20/03/2010 03','dd/mm/yyyy HH24'),138 from dual union all select to_date('20/03/2010 04','dd/mm/yyyy HH24'),416 from dual union all select to_date('20/03/2010 05','dd/mm/yyyy HH24'),196 from dual union all select to_date('20/03/2010 06','dd/mm/yyyy HH24'),246 from dual union all select to_date('20/03/2010 07','dd/mm/yyyy HH24'),176 from dual union all select to_date('20/03/2010 08','dd/mm/yyyy HH24'),124 from dual union all select to_date('20/03/2010 09','dd/mm/yyyy HH24'),128 from dual union all select to_date('20/03/2010 10','dd/mm/yyyy HH24'),32010 from dual union all select to_date('20/03/2010 11','dd/mm/yyyy HH24'),384 from dual union all select to_date('20/03/2010 12','dd/mm/yyyy HH24'),368 from dual union all select to_date('20/03/2010 13','dd/mm/yyyy HH24'),392 from dual union all select to_date('20/03/2010 14','dd/mm/yyyy HH24'),374 from dual union all select to_date('20/03/2010 15','dd/mm/yyyy HH24'),350 from dual union all select to_date('20/03/2010 16','dd/mm/yyyy HH24'),248 from dual union all select to_date('20/03/2010 17','dd/mm/yyyy HH24'),396 from dual union all select to_date('20/03/2010 18','dd/mm/yyyy HH24'),388 from dual union all select to_date('20/03/2010 19','dd/mm/yyyy HH24'),360 from dual union all select to_date('20/03/2010 20','dd/mm/yyyy HH24'),194 from dual union all select to_date('20/03/2010 21','dd/mm/yyyy HH24'),234 from dual union all select to_date('20/03/2010 22','dd/mm/yyyy HH24'),328 from dual union all select to_date('20/03/2010 23','dd/mm/yyyy HH24'),216 from dual From this table, how to rank() over 'value', partitioning by each hour of the day? and select only the 1st ranked result?

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  • Scalable / Parallel Large Graph Analysis Library?

    - by Joel Hoff
    I am looking for good recommendations for scalable and/or parallel large graph analysis libraries in various languages. The problems I am working on involve significant computational analysis of graphs/networks with 1-100 million nodes and 10 million to 1+ billion edges. The largest SMP computer I am using has 256 GB memory, but I also have access to an HPC cluster with 1000 cores, 2 TB aggregate memory, and MPI for communication. I am primarily looking for scalable, high-performance graph libraries that could be used in either single or multi-threaded scenarios, but parallel analysis libraries based on MPI or a similar protocol for communication and/or distributed memory are also of interest for high-end problems. Target programming languages include C++, C, Java, and Python. My research to-date has come up with the following possible solutions for these languages: C++ -- The most viable solutions appear to be the Boost Graph Library and Parallel Boost Graph Library. I have looked briefly at MTGL, but it is currently slanted more toward massively multithreaded hardware architectures like the Cray XMT. C - igraph and SNAP (Small-world Network Analysis and Partitioning); latter uses OpenMP for parallelism on SMP systems. Java - I have found no parallel libraries here yet, but JGraphT and perhaps JUNG are leading contenders in the non-parallel space. Python - igraph and NetworkX look like the most solid options, though neither is parallel. There used to be Python bindings for BGL, but these are now unsupported; last release in 2005 looks stale now. Other topics here on SO that I've looked at have discussed graph libraries in C++, Java, Python, and other languages. However, none of these topics focused significantly on scalability. Does anyone have recommendations they can offer based on experience with any of the above or other library packages when applied to large graph analysis problems? Performance, scalability, and code stability/maturity are my primary concerns. Most of the specialized algorithms will be developed by my team with the exception of any graph-oriented parallel communication or distributed memory frameworks (where the graph state is distributed across a cluster).

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  • Using datetime float representation as primary key

    - by devanalyst
    From my experience I have learn that using an surrogate INT data type column as primary key esp. an IDENTITY key column offers better performance than using GUID or char/varchar data type column as primary key. I try to use IDENTITY key as primary key wherever possible. But recently I came across a schema where the tables were horizontally partitioned and were managed via a Partitioned view. So the tables could not have an IDENTITY column since that would make the Partitioned View non updatable. One work around for this was to create a dummy 'keygenerator' table with an identity column to generate IDs for primary key. But this would mean having a 'keygenerator' table for each of the Partitioned View. My next thought was to use float as a primary key. The reason is the following key algorithm that I devised DECLARE @KEY FLOAT SET @KEY = CONVERT(FLOAT,GETDATE())/100000.0 SET @KEY = @EMP_ID + @KEY Heres how it works. CONVERT(FLOAT,GETDATE()) gives float representation of current datetime since internally all datetime are represented by SQL as a float value. CONVERT(FLOAT,GETDATE())/100000.0 converts the float representation into complete decimal value i.e. all digits are pushed to right side of ".". @KEY = @EMP_ID + @KEY adds the Employee ID which is an integer to this decimal value. The logic is that the Employee ID is guaranteed to be unique across sessions since an employee cannot connect to an application more than once at the same time. And for the same employee each time a key will be generated the current datetime will be unique. In all an unique key across all employee sessions and across time. So for Emp Ids 11 and 12, I have key values like 12.40046693321566357, 11.40046693542361111 But my concern whether float data type as primary key offer benefits compared to choosing GUID or char/varchar as primary keys. Also important thing is because of partitioning the float column is going to be part of a composite key.

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  • Beginner SQL question: querying gold and silver tag badges in Stack Exchange Data Explorer

    - by polygenelubricants
    I'm using the Stack Exchange Data Explorer to learn SQL, but I think the fundamentals of the question is applicable to other databases. I'm trying to query the Badges table, which according to Stexdex (that's what I'm going to call it from now on) has the following schema: Badges Id UserId Name Date This works well for badges like [Epic] and [Legendary] which have unique names, but the silver and gold tag-specific badges seems to be mixed in together by having the same exact name. Here's an example query I wrote for [mysql] tag: SELECT UserId as [User Link], Date FROM Badges Where Name = 'mysql' Order By Date ASC The (slightly annotated) output is: as seen on stexdex: User Link Date --------------- ------------------- // all for silver except where noted Bill Karwin 2009-02-20 11:00:25 Quassnoi 2009-06-01 10:00:16 Greg 2009-10-22 10:00:25 Quassnoi 2009-10-31 10:00:24 // for gold Bill Karwin 2009-11-23 11:00:30 // for gold cletus 2010-01-01 11:00:23 OMG Ponies 2010-01-03 11:00:48 Pascal MARTIN 2010-02-17 11:00:29 Mark Byers 2010-04-07 10:00:35 Daniel Vassallo 2010-05-14 10:00:38 This is consistent with the current list of silver and gold earners at the moment of this writing, but to speak in more timeless terms, as of the end of May 2010 only 2 users have earned the gold [mysql] tag: Quassnoi and Bill Karwin, as evidenced in the above result by their names being the only ones that appear twice. So this is the way I understand it: The first time an Id appears (in chronological order) is for the silver badge The second time is for the gold Now, the above result mixes the silver and gold entries together. My questions are: Is this a typical design, or are there much friendlier schema/normalization/whatever you call it? In the current design, how would you query the silver and gold badges separately? GROUP BY Id and picking the min/max or first/second by the Date somehow? How can you write a query that lists all the silver badges first then all the gold badges next? Imagine also that the "real" query may be more complicated, i.e. not just listing by date. How would you write it so that it doesn't have too many repetition between the silver and gold subqueries? Is it perhaps more typical to do two totally separate queries instead? What is this idiom called? A row "partitioning" query to put them into "buckets" or something?

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