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  • Slow speed for UFS mounted drive in Linux

    - by Incredible
    Hi, I have a disk that has Sun OS disk, (ufs filesystem). And I want to mount it in my debain machine with read/write mode. Since by deafult linux doesn't support write to ufs filesystem. I had to recompile the kernel by setting to the flag CONFIG_UFS_FS_WRITE=y. Now I am able to write to the filesystem, but the read/write speed is very slow. It is around 120 KB/s. Any idea what is wrong and how to resolve this issue? Thank you in advance.

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  • IP packet proxy solutions? Riverbed alternative

    - by Ruvan
    I have stumbled upon Riverbed.com's products which basically has the capability to hash chunks of IP data and subsequently store them to disk. I'm looking for an open source / cheaper alternative. WANProxy is the exact equivalent except that it only keeps data in-memory and can't store the data to disk which is a requirement for our solution. I'm basically looking for a proxy which not only looks at the files (filenames) but the data itself being transmitted at the packet level. Anyone? Thanks!

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  • How does Linux's unlink on a NTFS filesystem differs from Window's own implementation?

    - by DavideRossi
    I have an external USB disk with an NTFS filesystem on it. If I remove a file from Windows and I run one of the several "undelete" utilities (say, TestDisk) I can easily recover the file (because "it's still there but it's marked as deleted"). If I remove the file from Linux (I'm using Ubuntu) no utility can recover the file (unless I use a deep-search signature-based one). Why? It looks like Linux does not just "mark it as deleted" but it wipes away some on-disk structure, is this the case?

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  • VMWare Input/Output error on ubuntu host Win7 guest

    - by CShipley
    I am running ubuntu 10.10 as my host with Windows 7 as the guest. About a couple weeks ago I started getting error pop-ups from vmware reporting inability to read or write to a particular file. On futher investigation, I've noticed that I cannot copy that particular file from the linux command line even as root. I get the same input/output error. The SMART utility tells me I have 69 bad sectors on the disk (it is 1 TB) So my question is 1) How do I tell if that HD is going bad? 2) How can I move the VM files to a different part of the disk if I get read/write errors when I try to copy?

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  • Replacing GRUB2 with Windows boot loader

    - by KovBal
    I'm trying to replace GRUB2 with Windows' standard boot loader (bootmgr?), but I can't get it to work. My Windows 7 install is in a single NTFS partition, which is marked as active (boot flag is set). First, I tried the automatic repair with the install disk, but it didn't detect any problems. Then I ran bootrec /fixmbr and bootrec /fixboot, but all I got was a black screen at boot with a blinking cursor. After that I created a boot partition for GRUB2, I figured, at least I can use it to chainload, but it give me a "disk reading error". If I used GRUB's ntldr loader, than I got error 0xc0000225 (some sort of BCD error). I tried to rebuild the BCD from the rescue environment, and it was successful, but the error didn't go away. Update: I've tried to rebuild the BCD, but nothing changed...

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  • Will readyboost speed up a secondary partion or harddrive?

    - by Sebastian
    I'm building a new computer and plan on using a few spare USB sticks with readyboost to cache disk writes. I'll be running Windows 7 Enterprise SP1 x64 I have a single 2 TB disk, and plan to make a partition for windows (100 GB) and use the rest for data. I know Readyboost will work nicely for the C drive, but am unable to find any information on whether it will accelerate a second drive or partition. Just to clarify, I'm NOT trying to use the harddrive instead of the usb sticks. I'm trying to speed up the second partition using the USB sticks So, will readyboost work for a secondary partion or harddrive?

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  • Cloned Windows 7 to new HDD and want to change the drive letter to C

    - by Hoppe
    I used Clonezilla to clone my existing hard drive to a new one I bought. I then changed the BIOS to set the new drive as the first in the boot sequence. I'm pretty sure that I'm still running Windows 7 on the old drive. My old drive is marked as C. Now that I don't have a disk drive any more, how I do I swap the drive letter from J: to C:? I tried to change it in the disk management section of "Manage", but it reports: "the parameter is incorrect".

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  • PCI IDE Controller

    - by mercutio
    I have a suspicion that the onboard IDE controllers may not be working. Every disk I use to setup this machine reports as damaged (using a win xp installation to test, since it gets to partition setup fastest) So, I popped an IDE PCI Controller card in, to test with, but no drives are showing up in the bios now. I went into setup and changed the BIOS settings to disable onboard IDE1 and 2 to test, but still didn't detect the drives. How do I get that working? It's a standard PC with a 160GB disk and DVD Drive on master and slave channels on a single cable, if that helps. Let me know what else I need to state.

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  • Replacing a non-failing drive in a RAID-0 array [migrated]

    - by TallFurryMan
    I have a Windows 7 machine booting on a RAID-0 pair of 500GB disks, controlled by an ICH9R. One of those is indicating an end-To-end SMART failure. I added a spare disk as a temporary workaround, before receiving another to replace the failing one (prices are awful these days). The RAID-0 rebuilt on the spare and dropped the failing one from the array, as expected. Now that I received the new drive, what are my options to reintegrate it in the array? My first thought was to simply clone the temporary disk to the new one while the array is offline, but shouldn't there be a way to force a second rebuild, just as if the temporary drive had a warning, and drop that temporary from the array?

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  • Too Much Swapping, even though RAM is 2/3 Empty

    - by indyaah
    I have a VPS with 9GB RAM, 300GB HDD, 3 GB Swap, 7 Cores. The OS is CentOS 5.7 Final. I have postgres9.0 running on my machine, with proper tuning done (at least by book/wiki of PostgreSQL). What happens is most of the times when some complex query run (by complex I mean select with maximum 3 Joins), eventhough 66% of my RAM is unused there is ~99% swapping is happening. Plus it screws up my disk IO which is most of the time reaching ~100% and slows down everything else. (I tend to believe something's wrong with my disk.) I dont understand the reason of this much of swapping happening. Is it because of context switching?? Most of the time my processors are idle, while the IO wait goes upto 30% during pick times. Would appreciate if some can shed some light on it. Thanks.

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  • messed System Files on Mac PPC

    - by glider
    My buddy deleted her System folder from her PPC Mac wanting to get that space for something else. She copied it first in another drive (she had partitioned disk).She haven't emptied the Trash Bin yet. The screen just froze right after she moved the folder to Trash. We tried to use the install disk but even if we try Power-C on booting,it would try to continue,display the apple logo page then quickly follow it with black screen filled with dumps of hex codes and "We are hanging here..." We have a Windows-based PC that we tried to connect using ethernet cable but we can't find her computer from there. What should we do now???

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  • How create a virtual network for practice?

    - by light
    I need to organize a virtual network for practice with Windows Server 2008 and several workstations with Windows OS. To make it all I only have a laptop with Dual-Core 2.10Ghz, 3 GB RAM, 50 GB free space and Windows 7 on it. Also I have external USB 3.0 hard-drive with 250GB free space and flash disk with 8GB space. What can you suggest? Because I have limited resources, I think to install ESXi 5.1 on the main disk of my laptop as second OS, with installed Windows 7. I have no idea will it work or not, but after that I want to try to create hosts using availible space on external hard-drive. Is it possible?

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  • Rebuild mdadm RAID5 array with fewer disks

    - by drjeep
    I have a 4 disk RAID5 array, one of which is starting to fail according to smartd. However, since I'm using less than half the space on /dev/md0, I'd like to rebuild the array without the failing disk. The closest scenario I've been able to find online has been this post, however it contains bits that don't apply to me (LVM volumes) and also doesn't explain how I go about resizing the partition after I'm done. Please note I have backups of important data, but I'd like to avoid rebuilding the array from scratch if possible.

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  • I want to replace 120GB SSD with 240GB SSD. Will I need to reinstall Windows?

    - by Borek
    Some SSD vendors offer "upgrade kits" that are supposed to move the operating system from the old disk to the new one without the need to reinstall it, however, it didn't really quite work for me in the past and I always ended up installing the system from scratch. I'd really like to avoid it now so I'd like to ask: Generally speaking, when upgrading from a smaller to a larger SSD, will something like Windows Complete PC Backup and Restore work? Has someone experienced a seamless upgrade? Is there a proven tool to do that? (That worked for you, not that should work theoretically.) My problem usually is that the restored system sees a different disk, thinks it is a different hardware and doesn't want to restore.

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  • VMWare Input/Output error on ubuntu host Win7 guest

    - by CShipley
    I am running ubuntu 10.10 as my host with Windows 7 as the guest. About a couple weeks ago I started getting error pop-ups from vmware reporting inability to read or write to a particular file. On futher investigation, I've noticed that I cannot copy that particular file from the linux command line even as root. I get the same input/output error. The SMART utility tells me I have 69 bad sectors on the disk (it is 1 TB) So my question is 1) How do I tell if that HD is going bad? 2) How can I move the VM files to a different part of the disk if I get read/write errors when I try to copy?

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  • Recover snap server data

    - by Ugg
    Hi I have a snap server 110 the machine powers on ok and the healthcheck passes but unable to connect no responce on the assigned ip or any ability to reach the device via the snap server manager. Believe the device is powering on but not loading the OS. Tried pulling the disk running and hooking up to a windows PC via USB, and using disk internals linux reader I am unable to access two of the partitions. ( one of which is the large data partition). There are three partitions on the the drice only one is accessible via Linux reader. I am looking to recover the data of the drive can anyone suggest a DIY option please?

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  • CentOS I/O blocking flushing dirtypages

    - by user3662224
    I have an Apache webserver on CentOS. It is not doing anything fantastic or complicated at all but it does at intervals experience a high load (120 for 4 CPUs) for some reason. During this time I see high waits and write durations. I have narrowed this down to flushing of dirtypages to disk to make room for new data. I have tried many things and talked to the developers who are also puzzled by this. I am stumped. Details: vmware virtual guest server 4 cpus 12G RAM Apache PHP I have 40 servers in this cluster that share the same disk structure. Only the webservers are experiencing this issue. Any ideas?

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  • Installation stuck on "Installation Type" screen

    - by Andrew Latham
    I am trying to install Ubuntu 11.10 with Windows 7 from a CD. I am using an HP Pavilion dm4. I've never used Ubuntu (or any Linux) before. Everything goes alright until I get to the "Installation Type" screen. Instead of giving me options, it just has a blank menu, and all the buttons are disabled. When I click "Continue", it gives me an error saying that it can't find the root or something like that. The trial version works fine, but I can't actually install it. Everything on the trial version is really slow, presumably because everything is on the CD or the Windows partition. I did some research, but the only post I could find was http://ubuntuforums.org/showthread.php?t=1870478 Where the only advice is to format the entire drive, which I'm not willing to do. Any suggestions? I'm downloading 10.04 right now and I'm going to try with that instead. EDIT: 10.04 didn't work either. I got to the partitioning screen and got the same problem. I read some more forums, loaded up 11.10 trial from the disk, opened the Terminal and typed sudo apt-get remove dmraid and then y. Then I was actually able to see something on the "Installation type" page: "Erase disk and install Ubuntu" or "Something else". Which is weird, since Windows 7 should be installed. When I click Something Else, I get: /dev/sda /dev/sdb /dev/sdb1 (ntfs) (208 MB) (69 MB used) /dev/sdb2 (ntfs) (477542 MB) (unknown used) /dev/sdb3 (ntfs) (18085 MB) (16094 MB used) /dev/sdb4 (fat32) (4265 MB) (3084 MB used) I have no idea what any of this means. Also, my device for boot loader installation changed from /dev/sda to /dev/sda ATA SAMSUNG MZMPA032 (32.0 GB)

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  • Run Windows in Ubuntu with VMware Player

    - by Matthew Guay
    Are you an enthusiast who loves their Ubuntu Linux experience but still needs to use Windows programs?  Here’s how you can get the full Windows experience on Ubuntu with the free VMware Player. Linux has become increasingly consumer friendly, but still, the wide majority of commercial software is only available for Windows and Macs.  Dual-booting between Windows and Linux has been a popular option for years, but this is a frustrating solution since you have to reboot into the other operating system each time you want to run a specific application.  With virtualization, you’ll never have to make this tradeoff.  VMware Player makes it quick and easy to install any edition of Windows in a virtual machine.  With VMware’s great integration tools, you can copy and paste between your Linux and Windows programs and even run native Windows applications side-by-side with Linux ones. Getting Started Download the latest version of VMware Player for Linux, and select either the 32-bit or 64-bit version, depending on your system.  VMware Player is a free download, but requires registration.  Sign in with your VMware account, or create a new one if you don’t already have one. VMware Player is fairly easy to install on Linux, but you will need to start out the installation from the terminal.  First, enter the following to make sure the installer is marked as executable, substituting version/build_number for the version number on the end of the file you downloaded. chmod +x ./VMware-Player-version/build_number.bundle Then, enter the following to start the install, again substituting your version number: gksudo bash ./VMware-Player-version/build_number.bundle You may have to enter your administrator password to start the installation, and then the VMware Player graphical installer will open.  Choose whether you want to check for product updates and submit usage data to VMware, and then proceed with the install as normal. VMware Player installed in only a few minutes in our tests, and was immediately ready to run, no reboot required.  You can now launch it from your Ubuntu menu: click Applications \ System Tools \ VMware Player. You’ll need to accept the license agreement the first time you run it. Welcome to VMware Player!  Now you can create new virtual machines and run pre-built ones on your Ubuntu desktop. Install Windows in VMware Player on Ubuntu Now that you’ve got VMware setup, it’s time to put it to work.  Click the Create a New Virtual Machine as above to start making a Windows virtual machine. In the dialog that opens, select your installer disk or ISO image file that you want to install Windows from.  In this example, we’re select a Windows 7 ISO.  VMware will automatically detect the operating system on the disk or image.  Click Next to continue. Enter your Windows product key, select the edition of Windows to install, and enter your name and password. You can leave the product key field blank and enter it later.  VMware will ask if you want to continue without a product key, so just click Yes to continue. Now enter a name for your virtual machine and select where you want to save it.  Note: This will take up at least 15Gb of space on your hard drive during the install, so make sure to save it on a drive with sufficient storage space. You can choose how large you want your virtual hard drive to be; the default is 40Gb, but you can choose a different size if you wish.  The entire amount will not be used up on your hard drive initially, but the virtual drive will increase in size up to your maximum as you add files.  Additionally, you can choose if you want the virtual disk stored as a single file or as multiple files.  You will see the best performance by keeping the virtual disk as one file, but the virtual machine will be more portable if it is broken into smaller files, so choose the option that will work best for your needs. Finally, review your settings, and if everything looks good, click Finish to create the virtual machine. VMware will take over now, and install Windows without any further input using its Easy Install.  This is one of VMware’s best features, and is the main reason we find it the easiest desktop virtualization solution to use.   Installing VMware Tools VMware Player doesn’t include the VMware Tools by default; instead, it automatically downloads them for the operating system you’re installing.  Once you’ve downloaded them, it will use those tools anytime you install that OS.  If this is your first Windows virtual machine to install, you may be prompted to download and install them while Windows is installing.  Click Download and Install so your Easy Install will finish successfully. VMware will then download and install the tools.  You may need to enter your administrative password to complete the install. Other than this, you can leave your Windows install unattended; VMware will get everything installed and running on its own. Our test setup took about 30 minutes, and when it was done we were greeted with the Windows desktop ready to use, complete with drivers and the VMware tools.  The only thing missing was the Aero glass feature.  VMware Player is supposed to support the Aero glass effects in virtual machines, and although this works every time when we use VMware Player on Windows, we could not get it to work in Linux.  Other than that, Windows is fully ready to use.  You can copy and paste text, images, or files between Ubuntu and Windows, or simply drag-and-drop files between the two. Unity Mode Using Windows in a window is awkward, and makes your Windows programs feel out of place and hard to use.  This is where Unity mode comes in.  Click Virtual Machine in VMware’s menu, and select Enter Unity. Your Windows desktop will now disappear, and you’ll see a new Windows menu underneath your Ubuntu menu.  This works the same as your Windows Start Menu, and you can open your Windows applications and files directly from it. By default, programs from Windows will have a colored border and a VMware badge in the corner.  You can turn this off from the VMware settings pane.  Click Virtual Machine in VMware’s menu and select Virtual Machine Settings.  Select Unity under the Options tab, and uncheck the Show borders and Show badges boxes if you don’t want them. Unity makes your Windows programs feel at home in Ubuntu.  Here we have Word 2010 and IE8 open beside the Ubuntu Help application.  Notice that the Windows applications show up in the taskbar on the bottom just like the Linux programs.  If you’re using the Compiz graphics effects in Ubuntu, your Windows programs will use them too, including the popular wobbly windows effect. You can switch back to running Windows inside VMware Player’s window by clicking the Exit Unity button in the VMware window. Now, whenever you want to run Windows applications in Linux, you can quickly launch it from VMware Player. Conclusion VMware Player is a great way to run Windows on your Linux computer.  It makes it extremely easy to get Windows installed and running, lets you run your Windows programs seamlessly alongside your Linux ones.  VMware products work great in our experience, and VMware Player on Linux was no exception. If you’re a Windows user and you’d like to run Ubuntu on Windows, check out our article on how to Run Ubuntu in Windows with VMware Player. Link Download VMware Player 3 (Registration required) Download Windows 7 Enterprise 90-day trial Similar Articles Productive Geek Tips Enable Copy and Paste from Ubuntu VMware GuestInstall VMware Tools on Ubuntu Edgy EftRestart the Ubuntu Gnome User Interface QuicklyHow to Add a Program to the Ubuntu Startup List (After Login)How To Run Ubuntu in Windows 7 with VMware Player TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Snagit 10 Get a free copy of WinUtilities Pro 2010 World Cup Schedule Boot Snooze – Reboot and then Standby or Hibernate Customize Everything Related to Dates, Times, Currency and Measurement in Windows 7 Google Earth replacement Icon (Icons we like) Build Great Charts in Excel with Chart Advisor

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  • Ubuntu 12.04 on Amazon EC2: /dev/xvda1 will be checked for errors at next reboot?

    - by cwd
    I'm running the lastest Ubuntu 12.04 AMI (ami-a29943cb) from Canonical on Amazon EC2 and quite often when I log in I get the message: *** /dev/xvda1 will be checked for errors at next reboot *** I have read a bunch of documentation on this and seem to understand that every so many reboots (around 37 see Mount count / Maximum mount count below) Ubuntu wants to check a disk for errors. I can see that by using dumpe2fs -h /dev/xvda1 (reference) to get information such as: Last mounted on: / Filesystem UUID: 1ad27d06-4ecf-493d-bb19-4710c3caf924 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize Filesystem flags: signed_directory_hash Default mount options: (none) Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 524288 Block count: 2097152 Reserved block count: 104857 Free blocks: 1778055 Free inodes: 482659 First block: 0 Block size: 4096 Fragment size: 4096 Reserved GDT blocks: 511 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 8192 Inode blocks per group: 512 Flex block group size: 16 Filesystem created: Tue Apr 24 03:07:48 2012 Last mount time: Thu Nov 8 03:17:58 2012 Last write time: Tue Apr 24 03:08:52 2012 Mount count: 3 Maximum mount count: 37 Last checked: Tue Apr 24 03:07:48 2012 Check interval: 15552000 (6 months) Next check after: Sun Oct 21 03:07:48 2012 Lifetime writes: 2454 MB Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 256 Required extra isize: 28 Desired extra isize: 28 Journal inode: 8 Default directory hash: half_md4 Directory Hash Seed: 0a25e04c-6169-4d68-bfa6-a1acd8e39632 Journal backup: inode blocks Journal features: journal_incompat_revoke Journal size: 128M Journal length: 32768 Journal sequence: 0x0000158b Journal start: 1 I've tried these things to get rid of the message and usually the badblocks is what does it for me: Run this command and reboot: sudo touch /forcefsck Run badblocks to check the disk: badblocks /dev/sda1 Edit /etc/fstab and change the last "0" which is the fs_passno column accordingly and then reboot: The root filesystem should be specified with a fs_passno of 1, and other filesystems should have a fs_passno of 2. I don't understand: If this is a virtual drive shouldn't it be less prone to errors? Was the image created with one of the flags set? If not what is triggering it? Why is fs_passno set to 0 on Amazon EC2 Ubuntu images? This is not the first one that is like this.

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  • External HDD USB 3.0 failure

    - by Philip
    [ 2560.376113] usb 9-1: new high-speed USB device number 2 using xhci_hcd [ 2560.376186] usb 9-1: Device not responding to set address. [ 2560.580136] usb 9-1: Device not responding to set address. [ 2560.784104] usb 9-1: device not accepting address 2, error -71 [ 2560.840127] hub 9-0:1.0: unable to enumerate USB device on port 1 [ 2561.080182] usb 10-1: new SuperSpeed USB device number 5 using xhci_hcd [ 2566.096163] usb 10-1: device descriptor read/8, error -110 [ 2566.200096] usb 10-1: new SuperSpeed USB device number 5 using xhci_hcd [ 2571.216175] usb 10-1: device descriptor read/8, error -110 [ 2571.376138] hub 10-0:1.0: unable to enumerate USB device on port 1 [ 2571.744174] usb 10-1: new SuperSpeed USB device number 7 using xhci_hcd [ 2576.760116] usb 10-1: device descriptor read/8, error -110 [ 2576.864074] usb 10-1: new SuperSpeed USB device number 7 using xhci_hcd [ 2581.880153] usb 10-1: device descriptor read/8, error -110 [ 2582.040123] hub 10-0:1.0: unable to enumerate USB device on port 1 [ 2582.224139] hub 9-0:1.0: unable to enumerate USB device on port 1 [ 2582.464177] usb 10-1: new SuperSpeed USB device number 9 using xhci_hcd [ 2587.480122] usb 10-1: device descriptor read/8, error -110 [ 2587.584079] usb 10-1: new SuperSpeed USB device number 9 using xhci_hcd [ 2592.600150] usb 10-1: device descriptor read/8, error -110 [ 2592.760134] hub 10-0:1.0: unable to enumerate USB device on port 1 [ 2593.128175] usb 10-1: new SuperSpeed USB device number 11 using xhci_hcd [ 2598.144183] usb 10-1: device descriptor read/8, error -110 [ 2598.248109] usb 10-1: new SuperSpeed USB device number 11 using xhci_hcd [ 2603.264171] usb 10-1: device descriptor read/8, error -110 [ 2603.480157] usb 10-1: new SuperSpeed USB device number 12 using xhci_hcd [ 2608.496162] usb 10-1: device descriptor read/8, error -110 [ 2608.600091] usb 10-1: new SuperSpeed USB device number 12 using xhci_hcd [ 2613.616166] usb 10-1: device descriptor read/8, error -110 [ 2613.832170] usb 10-1: new SuperSpeed USB device number 13 using xhci_hcd [ 2618.848135] usb 10-1: device descriptor read/8, error -110 [ 2618.952079] usb 10-1: new SuperSpeed USB device number 13 using xhci_hcd [ 2623.968155] usb 10-1: device descriptor read/8, error -110 [ 2624.184176] usb 10-1: new SuperSpeed USB device number 14 using xhci_hcd [ 2629.200124] usb 10-1: device descriptor read/8, error -110 [ 2629.304075] usb 10-1: new SuperSpeed USB device number 14 using xhci_hcd [ 2634.320172] usb 10-1: device descriptor read/8, error -110 [ 2634.424135] hub 10-0:1.0: unable to enumerate USB device on port 1 [ 2634.776186] usb 10-1: new SuperSpeed USB device number 15 using xhci_hcd [ 2639.792105] usb 10-1: device descriptor read/8, error -110 [ 2639.896090] usb 10-1: new SuperSpeed USB device number 15 using xhci_hcd [ 2644.912172] usb 10-1: device descriptor read/8, error -110 [ 2645.128174] usb 10-1: new SuperSpeed USB device number 16 using xhci_hcd [ 2650.144160] usb 10-1: device descriptor read/8, error -110 [ 2650.248062] usb 10-1: new SuperSpeed USB device number 16 using xhci_hcd [ 2655.264120] usb 10-1: device descriptor read/8, error -110 [ 2655.480182] usb 10-1: new SuperSpeed USB device number 17 using xhci_hcd [ 2660.496121] usb 10-1: device descriptor read/8, error -110 [ 2660.600086] usb 10-1: new SuperSpeed USB device number 17 using xhci_hcd [ 2665.616167] usb 10-1: device descriptor read/8, error -110 [ 2665.832177] usb 10-1: new SuperSpeed USB device number 18 using xhci_hcd [ 2670.848110] usb 10-1: device descriptor read/8, error -110 [ 2670.952066] usb 10-1: new SuperSpeed USB device number 18 using xhci_hcd [ 2675.968081] usb 10-1: device descriptor read/8, error -110 [ 2676.072124] hub 10-0:1.0: unable to enumerate USB device on port 1 [ 2786.104531] xhci_hcd 0000:02:00.0: remove, state 4 [ 2786.104546] usb usb10: USB disconnect, device number 1 [ 2786.104686] xHCI xhci_drop_endpoint called for root hub [ 2786.104692] xHCI xhci_check_bandwidth called for root hub [ 2786.104942] xhci_hcd 0000:02:00.0: USB bus 10 deregistered [ 2786.105054] xhci_hcd 0000:02:00.0: remove, state 4 [ 2786.105065] usb usb9: USB disconnect, device number 1 [ 2786.105176] xHCI xhci_drop_endpoint called for root hub [ 2786.105181] xHCI xhci_check_bandwidth called for root hub [ 2786.109787] xhci_hcd 0000:02:00.0: USB bus 9 deregistered [ 2786.110134] xhci_hcd 0000:02:00.0: PCI INT A disabled [ 2794.268445] pci 0000:02:00.0: [1b73:1000] type 0 class 0x000c03 [ 2794.268483] pci 0000:02:00.0: reg 10: [mem 0x00000000-0x0000ffff] [ 2794.268689] pci 0000:02:00.0: PME# supported from D0 D3hot [ 2794.268700] pci 0000:02:00.0: PME# disabled [ 2794.276383] pci 0000:02:00.0: BAR 0: assigned [mem 0xd7800000-0xd780ffff] [ 2794.276398] pci 0000:02:00.0: BAR 0: set to [mem 0xd7800000-0xd780ffff] (PCI address [0xd7800000-0xd780ffff]) [ 2794.276419] pci 0000:02:00.0: no hotplug settings from platform [ 2794.276658] xhci_hcd 0000:02:00.0: enabling device (0000 -> 0002) [ 2794.276675] xhci_hcd 0000:02:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16 [ 2794.276762] xhci_hcd 0000:02:00.0: setting latency timer to 64 [ 2794.276771] xhci_hcd 0000:02:00.0: xHCI Host Controller [ 2794.276913] xhci_hcd 0000:02:00.0: new USB bus registered, assigned bus number 9 [ 2794.395760] xhci_hcd 0000:02:00.0: irq 16, io mem 0xd7800000 [ 2794.396141] xHCI xhci_add_endpoint called for root hub [ 2794.396144] xHCI xhci_check_bandwidth called for root hub [ 2794.396195] hub 9-0:1.0: USB hub found [ 2794.396203] hub 9-0:1.0: 1 port detected [ 2794.396305] xhci_hcd 0000:02:00.0: xHCI Host Controller [ 2794.396371] xhci_hcd 0000:02:00.0: new USB bus registered, assigned bus number 10 [ 2794.396496] xHCI xhci_add_endpoint called for root hub [ 2794.396499] xHCI xhci_check_bandwidth called for root hub [ 2794.396547] hub 10-0:1.0: USB hub found [ 2794.396553] hub 10-0:1.0: 1 port detected [ 2798.004084] usb 1-3: new high-speed USB device number 8 using ehci_hcd [ 2798.140824] scsi21 : usb-storage 1-3:1.0 [ 2820.176116] usb 1-3: reset high-speed USB device number 8 using ehci_hcd [ 2824.000526] scsi 21:0:0:0: Direct-Access BUFFALO HD-PZU3 0001 PQ: 0 ANSI: 6 [ 2824.002263] sd 21:0:0:0: Attached scsi generic sg2 type 0 [ 2824.003617] sd 21:0:0:0: [sdb] 1953463728 512-byte logical blocks: (1.00 TB/931 GiB) [ 2824.005139] sd 21:0:0:0: [sdb] Write Protect is off [ 2824.005149] sd 21:0:0:0: [sdb] Mode Sense: 1f 00 00 08 [ 2824.009084] sd 21:0:0:0: [sdb] No Caching mode page present [ 2824.009094] sd 21:0:0:0: [sdb] Assuming drive cache: write through [ 2824.011944] sd 21:0:0:0: [sdb] No Caching mode page present [ 2824.011952] sd 21:0:0:0: [sdb] Assuming drive cache: write through [ 2824.049153] sdb: sdb1 [ 2824.051814] sd 21:0:0:0: [sdb] No Caching mode page present [ 2824.051821] sd 21:0:0:0: [sdb] Assuming drive cache: write through [ 2824.051825] sd 21:0:0:0: [sdb] Attached SCSI disk [ 2839.536624] usb 1-3: USB disconnect, device number 8 [ 2844.620178] usb 10-1: new SuperSpeed USB device number 2 using xhci_hcd [ 2844.640281] scsi22 : usb-storage 10-1:1.0 [ 2850.326545] scsi 22:0:0:0: Direct-Access BUFFALO HD-PZU3 0001 PQ: 0 ANSI: 6 [ 2850.327560] sd 22:0:0:0: Attached scsi generic sg2 type 0 [ 2850.329561] sd 22:0:0:0: [sdb] 1953463728 512-byte logical blocks: (1.00 TB/931 GiB) [ 2850.329889] sd 22:0:0:0: [sdb] Write Protect is off [ 2850.329897] sd 22:0:0:0: [sdb] Mode Sense: 1f 00 00 08 [ 2850.330223] sd 22:0:0:0: [sdb] No Caching mode page present [ 2850.330231] sd 22:0:0:0: [sdb] Assuming drive cache: write through [ 2850.331414] sd 22:0:0:0: [sdb] No Caching mode page present [ 2850.331423] sd 22:0:0:0: [sdb] Assuming drive cache: write through [ 2850.384116] usb 10-1: USB disconnect, device number 2 [ 2850.392050] sd 22:0:0:0: [sdb] Unhandled error code [ 2850.392056] sd 22:0:0:0: [sdb] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK [ 2850.392061] sd 22:0:0:0: [sdb] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00 [ 2850.392074] end_request: I/O error, dev sdb, sector 0 [ 2850.392079] quiet_error: 70 callbacks suppressed [ 2850.392082] Buffer I/O error on device sdb, logical block 0 [ 2850.392194] ldm_validate_partition_table(): Disk read failed. [ 2850.392271] Dev sdb: unable to read RDB block 0 [ 2850.392377] sdb: unable to read partition table [ 2850.392581] sd 22:0:0:0: [sdb] READ CAPACITY failed [ 2850.392584] sd 22:0:0:0: [sdb] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK [ 2850.392588] sd 22:0:0:0: [sdb] Sense not available. [ 2850.392613] sd 22:0:0:0: [sdb] Asking for cache data failed [ 2850.392617] sd 22:0:0:0: [sdb] Assuming drive cache: write through [ 2850.392621] sd 22:0:0:0: [sdb] Attached SCSI disk [ 2850.732182] usb 10-1: new SuperSpeed USB device number 3 using xhci_hcd [ 2850.752228] scsi23 : usb-storage 10-1:1.0 [ 2851.752709] scsi 23:0:0:0: Direct-Access BUFFALO HD-PZU3 0001 PQ: 0 ANSI: 6 [ 2851.754481] sd 23:0:0:0: Attached scsi generic sg2 type 0 [ 2851.756576] sd 23:0:0:0: [sdb] 1953463728 512-byte logical blocks: (1.00 TB/931 GiB) [ 2851.758426] sd 23:0:0:0: [sdb] Write Protect is off [ 2851.758436] sd 23:0:0:0: [sdb] Mode Sense: 1f 00 00 08 [ 2851.758779] sd 23:0:0:0: [sdb] No Caching mode page present [ 2851.758787] sd 23:0:0:0: [sdb] Assuming drive cache: write through [ 2851.759968] sd 23:0:0:0: [sdb] No Caching mode page present [ 2851.759977] sd 23:0:0:0: [sdb] Assuming drive cache: write through [ 2851.817710] sdb: sdb1 [ 2851.820562] sd 23:0:0:0: [sdb] No Caching mode page present [ 2851.820568] sd 23:0:0:0: [sdb] Assuming drive cache: write through [ 2851.820572] sd 23:0:0:0: [sdb] Attached SCSI disk [ 2852.060352] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2852.076533] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2852.076538] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2852.196329] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2852.212593] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2852.212599] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2852.456290] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2852.472402] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2852.472408] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2852.624304] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2852.640531] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2852.640536] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2852.772296] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2852.788536] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2852.788541] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2852.920349] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2852.936536] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2852.936540] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2853.072287] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2853.088565] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2853.088570] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2884.176339] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2884.192561] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2884.192567] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2884.320349] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2884.336526] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2884.336531] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2884.468344] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2884.484551] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2884.484556] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2884.612349] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2884.628540] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2884.628545] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2884.756350] usb 10-1: reset SuperSpeed USB device number 3 using xhci_hcd [ 2884.772528] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b19060 [ 2884.772533] xhci_hcd 0000:02:00.0: xHCI xhci_drop_endpoint called with disabled ep f6b1908c [ 2884.848116] usb 10-1: USB disconnect, device number 3 [ 2884.851493] scsi 23:0:0:0: [sdb] killing request [ 2884.851501] scsi 23:0:0:0: [sdb] killing request [ 2884.851699] scsi 23:0:0:0: [sdb] Unhandled error code [ 2884.851702] scsi 23:0:0:0: [sdb] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK [ 2884.851708] scsi 23:0:0:0: [sdb] CDB: Read(10): 28 00 00 5f 2b ee 00 00 3e 00 [ 2884.851721] end_request: I/O error, dev sdb, sector 6237166 [ 2884.851726] Buffer I/O error on device sdb1, logical block 6237102 [ 2884.851730] Buffer I/O error on device sdb1, logical block 6237103 [ 2884.851738] Buffer I/O error on device sdb1, logical block 6237104 [ 2884.851741] Buffer I/O error on device sdb1, logical block 6237105 [ 2884.851744] Buffer I/O error on device sdb1, logical block 6237106 [ 2884.851747] Buffer I/O error on device sdb1, logical block 6237107 [ 2884.851750] Buffer I/O error on device sdb1, logical block 6237108 [ 2884.851753] Buffer I/O error on device sdb1, logical block 6237109 [ 2884.851757] Buffer I/O error on device sdb1, logical block 6237110 [ 2884.851807] scsi 23:0:0:0: [sdb] Unhandled error code [ 2884.851810] scsi 23:0:0:0: [sdb] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK [ 2884.851813] scsi 23:0:0:0: [sdb] CDB: Read(10): 28 00 00 5f 2c 2c 00 00 3e 00 [ 2884.851824] end_request: I/O error, dev sdb, sector 6237228 [ 2885.168190] usb 10-1: new SuperSpeed USB device number 4 using xhci_hcd [ 2885.188268] scsi24 : usb-storage 10-1:1.0 Please help me with my problem. I got this after running dmesg.

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  • BAD ARCHIVE MIRROR using PXE BOOT method

    - by omkar
    i m trying to automatically install UBUNTU on a client PC by using the method of PXE BOOT method....my Objectives are below:- i m following the steps given in this link installation using PXE BOOT 1:-the server will have a KICKSTART config file which contains the parameters for the OS installation and the files which are required for the OS installations. 2:-the client will have to detect this configuration along with the setup files and complete the installation without any input from the user. In my server i have installed DHCP3-server,Apache2 and TFTP for helping me with the installation. i have nearly achieved my first objective,i m able to boot my client using the files stored in the server,but during the installation stage it is asking me to "CHOOSE A MIRROR of UBUNTU ARCHIVE".i gave the server's IP address and the path in the server where the files are located but then too its giving me error "BAD ARCHIVE MIRROR". so is it possible that instead of downloading all the files from the internet and storing them on my disk , can i use the files which comes with the UBUNTU-CD, and how to store this files in what format (should i zip them ) on the disk. secondly i am also generating the ks.cfg which i wanted to give to the client for automatic installation of the OS ,so how should the configuration file be given to the installation process.

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  • Heaps of Trouble?

    - by Paul White NZ
    If you’re not already a regular reader of Brad Schulz’s blog, you’re missing out on some great material.  In his latest entry, he is tasked with optimizing a query run against tables that have no indexes at all.  The problem is, predictably, that performance is not very good.  The catch is that we are not allowed to create any indexes (or even new statistics) as part of our optimization efforts. In this post, I’m going to look at the problem from a slightly different angle, and present an alternative solution to the one Brad found.  Inevitably, there’s going to be some overlap between our entries, and while you don’t necessarily need to read Brad’s post before this one, I do strongly recommend that you read it at some stage; he covers some important points that I won’t cover again here. The Example We’ll use data from the AdventureWorks database, copied to temporary unindexed tables.  A script to create these structures is shown below: CREATE TABLE #Custs ( CustomerID INTEGER NOT NULL, TerritoryID INTEGER NULL, CustomerType NCHAR(1) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, ); GO CREATE TABLE #Prods ( ProductMainID INTEGER NOT NULL, ProductSubID INTEGER NOT NULL, ProductSubSubID INTEGER NOT NULL, Name NVARCHAR(50) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, ); GO CREATE TABLE #OrdHeader ( SalesOrderID INTEGER NOT NULL, OrderDate DATETIME NOT NULL, SalesOrderNumber NVARCHAR(25) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, CustomerID INTEGER NOT NULL, ); GO CREATE TABLE #OrdDetail ( SalesOrderID INTEGER NOT NULL, OrderQty SMALLINT NOT NULL, LineTotal NUMERIC(38,6) NOT NULL, ProductMainID INTEGER NOT NULL, ProductSubID INTEGER NOT NULL, ProductSubSubID INTEGER NOT NULL, ); GO INSERT #Custs ( CustomerID, TerritoryID, CustomerType ) SELECT C.CustomerID, C.TerritoryID, C.CustomerType FROM AdventureWorks.Sales.Customer C WITH (TABLOCK); GO INSERT #Prods ( ProductMainID, ProductSubID, ProductSubSubID, Name ) SELECT P.ProductID, P.ProductID, P.ProductID, P.Name FROM AdventureWorks.Production.Product P WITH (TABLOCK); GO INSERT #OrdHeader ( SalesOrderID, OrderDate, SalesOrderNumber, CustomerID ) SELECT H.SalesOrderID, H.OrderDate, H.SalesOrderNumber, H.CustomerID FROM AdventureWorks.Sales.SalesOrderHeader H WITH (TABLOCK); GO INSERT #OrdDetail ( SalesOrderID, OrderQty, LineTotal, ProductMainID, ProductSubID, ProductSubSubID ) SELECT D.SalesOrderID, D.OrderQty, D.LineTotal, D.ProductID, D.ProductID, D.ProductID FROM AdventureWorks.Sales.SalesOrderDetail D WITH (TABLOCK); The query itself is a simple join of the four tables: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #Prods P JOIN #OrdDetail D ON P.ProductMainID = D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID JOIN #OrdHeader H ON D.SalesOrderID = H.SalesOrderID JOIN #Custs C ON H.CustomerID = C.CustomerID ORDER BY P.ProductMainID ASC OPTION (RECOMPILE, MAXDOP 1); Remember that these tables have no indexes at all, and only the single-column sampled statistics SQL Server automatically creates (assuming default settings).  The estimated query plan produced for the test query looks like this (click to enlarge): The Problem The problem here is one of cardinality estimation – the number of rows SQL Server expects to find at each step of the plan.  The lack of indexes and useful statistical information means that SQL Server does not have the information it needs to make a good estimate.  Every join in the plan shown above estimates that it will produce just a single row as output.  Brad covers the factors that lead to the low estimates in his post. In reality, the join between the #Prods and #OrdDetail tables will produce 121,317 rows.  It should not surprise you that this has rather dire consequences for the remainder of the query plan.  In particular, it makes a nonsense of the optimizer’s decision to use Nested Loops to join to the two remaining tables.  Instead of scanning the #OrdHeader and #Custs tables once (as it expected), it has to perform 121,317 full scans of each.  The query takes somewhere in the region of twenty minutes to run to completion on my development machine. A Solution At this point, you may be thinking the same thing I was: if we really are stuck with no indexes, the best we can do is to use hash joins everywhere. We can force the exclusive use of hash joins in several ways, the two most common being join and query hints.  A join hint means writing the query using the INNER HASH JOIN syntax; using a query hint involves adding OPTION (HASH JOIN) at the bottom of the query.  The difference is that using join hints also forces the order of the join, whereas the query hint gives the optimizer freedom to reorder the joins at its discretion. Adding the OPTION (HASH JOIN) hint results in this estimated plan: That produces the correct output in around seven seconds, which is quite an improvement!  As a purely practical matter, and given the rigid rules of the environment we find ourselves in, we might leave things there.  (We can improve the hashing solution a bit – I’ll come back to that later on). Faster Nested Loops It might surprise you to hear that we can beat the performance of the hash join solution shown above using nested loops joins exclusively, and without breaking the rules we have been set. The key to this part is to realize that a condition like (A = B) can be expressed as (A <= B) AND (A >= B).  Armed with this tremendous new insight, we can rewrite the join predicates like so: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #OrdDetail D JOIN #OrdHeader H ON D.SalesOrderID >= H.SalesOrderID AND D.SalesOrderID <= H.SalesOrderID JOIN #Custs C ON H.CustomerID >= C.CustomerID AND H.CustomerID <= C.CustomerID JOIN #Prods P ON P.ProductMainID >= D.ProductMainID AND P.ProductMainID <= D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID ORDER BY D.ProductMainID OPTION (RECOMPILE, LOOP JOIN, MAXDOP 1, FORCE ORDER); I’ve also added LOOP JOIN and FORCE ORDER query hints to ensure that only nested loops joins are used, and that the tables are joined in the order they appear.  The new estimated execution plan is: This new query runs in under 2 seconds. Why Is It Faster? The main reason for the improvement is the appearance of the eager Index Spools, which are also known as index-on-the-fly spools.  If you read my Inside The Optimiser series you might be interested to know that the rule responsible is called JoinToIndexOnTheFly. An eager index spool consumes all rows from the table it sits above, and builds a index suitable for the join to seek on.  Taking the index spool above the #Custs table as an example, it reads all the CustomerID and TerritoryID values with a single scan of the table, and builds an index keyed on CustomerID.  The term ‘eager’ means that the spool consumes all of its input rows when it starts up.  The index is built in a work table in tempdb, has no associated statistics, and only exists until the query finishes executing. The result is that each unindexed table is only scanned once, and just for the columns necessary to build the temporary index.  From that point on, every execution of the inner side of the join is answered by a seek on the temporary index – not the base table. A second optimization is that the sort on ProductMainID (required by the ORDER BY clause) is performed early, on just the rows coming from the #OrdDetail table.  The optimizer has a good estimate for the number of rows it needs to sort at that stage – it is just the cardinality of the table itself.  The accuracy of the estimate there is important because it helps determine the memory grant given to the sort operation.  Nested loops join preserves the order of rows on its outer input, so sorting early is safe.  (Hash joins do not preserve order in this way, of course). The extra lazy spool on the #Prods branch is a further optimization that avoids executing the seek on the temporary index if the value being joined (the ‘outer reference’) hasn’t changed from the last row received on the outer input.  It takes advantage of the fact that rows are still sorted on ProductMainID, so if duplicates exist, they will arrive at the join operator one after the other. The optimizer is quite conservative about introducing index spools into a plan, because creating and dropping a temporary index is a relatively expensive operation.  It’s presence in a plan is often an indication that a useful index is missing. I want to stress that I rewrote the query in this way primarily as an educational exercise – I can’t imagine having to do something so horrible to a production system. Improving the Hash Join I promised I would return to the solution that uses hash joins.  You might be puzzled that SQL Server can create three new indexes (and perform all those nested loops iterations) faster than it can perform three hash joins.  The answer, again, is down to the poor information available to the optimizer.  Let’s look at the hash join plan again: Two of the hash joins have single-row estimates on their build inputs.  SQL Server fixes the amount of memory available for the hash table based on this cardinality estimate, so at run time the hash join very quickly runs out of memory. This results in the join spilling hash buckets to disk, and any rows from the probe input that hash to the spilled buckets also get written to disk.  The join process then continues, and may again run out of memory.  This is a recursive process, which may eventually result in SQL Server resorting to a bailout join algorithm, which is guaranteed to complete eventually, but may be very slow.  The data sizes in the example tables are not large enough to force a hash bailout, but it does result in multiple levels of hash recursion.  You can see this for yourself by tracing the Hash Warning event using the Profiler tool. The final sort in the plan also suffers from a similar problem: it receives very little memory and has to perform multiple sort passes, saving intermediate runs to disk (the Sort Warnings Profiler event can be used to confirm this).  Notice also that because hash joins don’t preserve sort order, the sort cannot be pushed down the plan toward the #OrdDetail table, as in the nested loops plan. Ok, so now we understand the problems, what can we do to fix it?  We can address the hash spilling by forcing a different order for the joins: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #Prods P JOIN #Custs C JOIN #OrdHeader H ON H.CustomerID = C.CustomerID JOIN #OrdDetail D ON D.SalesOrderID = H.SalesOrderID ON P.ProductMainID = D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID ORDER BY D.ProductMainID OPTION (MAXDOP 1, HASH JOIN, FORCE ORDER); With this plan, each of the inputs to the hash joins has a good estimate, and no hash recursion occurs.  The final sort still suffers from the one-row estimate problem, and we get a single-pass sort warning as it writes rows to disk.  Even so, the query runs to completion in three or four seconds.  That’s around half the time of the previous hashing solution, but still not as fast as the nested loops trickery. Final Thoughts SQL Server’s optimizer makes cost-based decisions, so it is vital to provide it with accurate information.  We can’t really blame the performance problems highlighted here on anything other than the decision to use completely unindexed tables, and not to allow the creation of additional statistics. I should probably stress that the nested loops solution shown above is not one I would normally contemplate in the real world.  It’s there primarily for its educational and entertainment value.  I might perhaps use it to demonstrate to the sceptical that SQL Server itself is crying out for an index. Be sure to read Brad’s original post for more details.  My grateful thanks to him for granting permission to reuse some of his material. Paul White Email: [email protected] Twitter: @PaulWhiteNZ

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