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• How can I set up FakeRAID/SoftRAID using mdadm without losing data?

  - by Danatela

  There is RAID0 of 2 drives connected through Silicon Image 3132 SATA SoftRAID controller. Under Windows it was partitioned as one dynamic GPT-disk having 4 TB NTFS volume. There is a lot of music and movies on the drive. I'm trying to get him to be seen under Ubuntu as a single disk, not as 2 by 2 terabytes. I tried to read it through dmraid, had no success, it is not displayed in /dev/mapper. Also tried to configure the kernel, but did not find anything suspicious, the driver for my controller was on. There is also a driver from the manufacturer, but it is only available for RHEL and SLES. Here it's reported that SoftRAID is supported by the kernel, but apparently not completely. If I thrust drives in the AMD controller, built into the motherboard, the drive is seen as a single, but the data is lost. I know about mdadm that it is able to ditch all the information on the disks. So, is it possible to somehow create an array without actually recording information on used drives and to make the system correctly identify sections on it later? Information about the array: /dev/sdf - Disk 0 /dev/sdg - Disk 1 Array type: Stripe Block Size: 64KB Also, a device /dev/md1 is created using command mknod /dev/md1 b 9 1

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• SD Card only mounted after a reboot

  - by hattenn

  I have a Kingston 2GB MicroSD and I plug it in via an inconix MicroSD Adapter to the internal card reader of my Samsung N210 Netbook with Ubuntu 10.10, but it doesn't show up. Only if I reboot the system when the card's plugged in it shows up. Why does it need a reboot for mounting? sudo fdisk -l gives the output below. But I can only see the drive when I reboot the computer while the card's plugged. Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x9a5a7990 Device Boot Start End Blocks Id System /dev/sda1 1 1959 15728640 27 Unknown Partition 1 does not end on cylinder boundary. /dev/sda2 * 1959 1972 102400 7 HPFS/NTFS /dev/sda3 1972 18992 136718750 83 Linux /dev/sda4 18992 19458 3738625 5 Extended /dev/sda5 18992 19458 3738624 82 Linux swap / Solaris Disk /dev/sdb: 1973 MB, 1973420032 bytes 60 heads, 59 sectors/track, 1088 cylinders Units = cylinders of 3540 * 512 = 1812480 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sdb1 1 1089 1927100+ 6 FAT16

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• It could be worse....

  - by Darryl Gove

  As "guest" pointed out, in my file I/O test I didn't open the file with O_SYNC, so in fact the time was spent in OS code rather than in disk I/O. It's a straightforward change to add O_SYNC to the open() call, but it's also useful to reduce the iteration count - since the cost per write is much higher: ... #define SIZE 1024 void test_write() { starttime(); int file = open("./test.dat",O_WRONLY|O_CREAT|O_SYNC,S_IWGRP|S_IWOTH|S_IWUSR); ... Running this gave the following results: Time per iteration 0.000065606310 MB/s Time per iteration 2.709711563906 MB/s Time per iteration 0.178590114758 MB/s Yup, disk I/O is way slower than the original I/O calls. However, it's not a very fair comparison since disks get written in large blocks of data and we're deliberately sending a single byte. A fairer result would be to look at the I/O operations per second; which is about 65 - pretty much what I'd expect for this system. It's also interesting to examine at the profiles for the two cases. When the write() was trapping into the OS the profile indicated that all the time was being spent in system. When the data was being written to disk, the time got attributed to sleep. This gives us an indication how to interpret profiles from apps doing I/O. It's the sleep time that indicates disk activity.

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• Install on Acer Aspire 4752

  - by user216962

  I am at my wits end with this computer. I bought and Acer Aspire 4752 with a fully loaded version of Windows 7 on it. I prefer Ubuntu so I began to install 14.04 from USB. Got the error: [Errno 5] Input/output error This is often due to a faulty CD/DVD disk or drive, or a faulty hard disk. It may help to clean the CD/DVD, to burn the CD/DVD at a lower speed, to clean the CD/DVD drive lens (cleaning kits are often available from electronics suppliers), to check whether the hard disk is old and in need of replacement, or to move the system to a cooler environment. So I tried a different USB stick, same error. Tried different versions of Ubuntu, got the same error. I've used startup disk creator and Unetbootin to make start USB boot devices. I can boot with the USB drive and run Ubuntu that way. I even checked the hard drive using the tools in Ubuntu. Everything was fine, except it said the hard drive was hot. I tried a different hard drive. Got same error above. I ran a test with mem86, everything was fine. No matter what I do, using the USB gives me the Errno5 error. I then switched to using DVDs. Now I keep getting an uncompression error when installing Ubuntu 14.04 or 12.04. I can't figure out for the life of me why I get nothing but errors. Can anyone help?

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• Help with dual booting Windows 8.1 Professional and Ubuntu 13.10

  - by user1292548

  I recently installed a clean version of Windows 8.1 Professional on my Lenovo Y500 (with Samsung 256GB 840 Pro SSD). I have Windows all set up and running normally. I am trying to dual boot Windows 8.1 and Ubuntu 13.10, but the installation procedure don't allow me to either "Install alongside..." or shows my SSD partitions correctly when I chose the "Something Else" option. I have created a 25GB partition of free space in the Windows disk manager, but on the installation screen on Ubuntu, it shows the whole drive as a free space. I have tried installing with a burned .ISO disk and a bootable USB, the results are the same for both. Windows Disk Management screen: http://imageshack.us/a/img855/9504/59zu.jpg The Ubuntu installation screen: http://imageshack.us/a/img62/2712/9g6i.jpg I've ran into this problem before when trying to dual boot Ubuntu and Windows 7 Professional a month ago. But I gave up and never resolved the issue. --EDIT-- I tried what Eero Aaltonen suggested, and this is my result: ubuntu@ubuntu:~$ sudo parted /dev/sda print Warning: /dev/sda contains GPT signatures, indicating that it has a GPT table. However, it does not have a valid fake msdos partition table, as it should. Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables. Or perhaps you deleted the GPT table, and are now using an msdos partition table. Is this a GPT partition table? Yes/No? yes Model: ATA Samsung SSD 840 (scsi) Disk /dev/sda: 256GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags ubuntu@ubuntu:~$

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• Dual Boot menu with Ubuntu and Windows 8 not showing up

  - by user180630

  I know a lot of posts have been written, and I had read most of them when I encountered the problem. None of them solved the problem. I have successfully installed Ubuntu 12.04 on top of Windows 8. Now my PC simply boots into Windows 8. If I press 'Esc' at start of BIOS, and then F9,the GRUB shows up and Ubuntu is listed at the top of the several options to boot from. I did run Boot-Repair once I logged into Ubuntu explicitly from GRUB as mentioned above. I did all said by Stormvirux in this link but was still unsuccessful. The debug info is listed here. Something which confuses me is the message which Boot-Repair stated after it did its job. You can now reboot your computer. Please do not forget to make your BIOS boot on sda (8004MB) disk! The boot files of [The OS now in use - Ubuntu 12.04.2 LTS] are far from the start of the disk. Your BIOS may not detect them. You may want to retry after creating a /boot partition (EXT4, 200MB, start of the disk). This can be performed via tools such as gParted. Then select this partition via the [Separate /boot partition:] option of [Boot Repair]. (https://help.ubuntu.com/community/BootPartition) I don't know why it says it is far from the start of the disk as I see it first in the GRUB menu which comes up at startup. One more input, when I try to place the GRUB in sda, Boot-Repair does not progress giving me the following error: GPT detected. Please create a BIOS-Boot partition (>1MB, unformatted filesystem, bios_grub flag). This can be performed via tools such as Gparted. Then try again. Alternatively, you can retry after activating the [Separate /boot/efi partition:] option. I had to select Separate /boot/efi partition: sdb2

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• SD Card only mounted after a reboot

  - by evothur

  Hi everyone. I have a Kingston 2GB MicroSD and I plug it in via an inconix MicroSD Adapter to the internal card reader of my Samsung N210 Netbook with Ubuntu 10.10, but it doesn't show up. Only if I reboot the system when the card's plugged in it shows up. Why does it need a reboot for mounting? sudo fdisk -l gives the output below. But I can only see the drive when I reboot the computer while the card's plugged. Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x9a5a7990 Device Boot Start End Blocks Id System /dev/sda1 1 1959 15728640 27 Unknown Partition 1 does not end on cylinder boundary. /dev/sda2 * 1959 1972 102400 7 HPFS/NTFS /dev/sda3 1972 18992 136718750 83 Linux /dev/sda4 18992 19458 3738625 5 Extended /dev/sda5 18992 19458 3738624 82 Linux swap / Solaris Disk /dev/sdb: 1973 MB, 1973420032 bytes 60 heads, 59 sectors/track, 1088 cylinders Units = cylinders of 3540 * 512 = 1812480 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sdb1 1 1089 1927100+ 6 FAT16

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• ubuntu 12.04 installer does not recognize drive partitions

  - by endless forms

  I recently purchased a new HP Pavilion HPE desktop running Windows 7. I am trying to install a dual-boot system with 12.04. However, when I run the LiveCD I only get as far as the "Install" window where you can select the partitions for your drives. On the bottom where it says "device for boot loader installation" I have "/dev/sda" and cannot select any other devices. All the options to change the drives are greyed out, most likely because there are no drives in the window. I partitioned my largest drive using the tools within Windows, then booted into the CD, but nothing shows up. I then used Gparted to change the new space from unallocated to an /ext2, and still nothing shows up. The installer does not recognize anything, but when I go into an Ubuntu session and use the disk utility manager I can see the partitions I made. Anything I do has to be done outside of the installer. I have no files on this new computer, so this is the perfect time to install a parallel OS. I would like avoid completely reinstalling Windows, however. I've been over the forums many times, but all the answers I've found have not worked for me. I also tried flagging the new, empty partition as boot, but that screwed Windows up. Also, the WUBI installer hits the same point and quits. I know that the disk itself is fine because I just made another dual boot system on a Gateway PC. This makes me think something within this computer is preventing the installer from "seeing" the drives. Any help would be much appreciated! Edit in response: The main part of the partitioning window shows no partitions, everything is blank. There is no way to add partitions, and all the buttons are useless. I've tried defragging my drive multiple times, and I also used the same disk to dual-boot another PC with no problems, so it's not the disk, it's definitely the computer.

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• Drive reporting incorrect free space

  - by Oli

  So I swapped my shiny SATA SSD for an even shinier PCI-E SSD. I run my core OS on the SSD because it's silly-fast. I did this on my old SSD so I created a new EXT4 partition and then just dded the data across (sorry I don't know the exact command I ran anymore) and after reinstalling grub, I booted onto the PCI-E SSD. At first glance everything had worked perfectly and things were running faster than ever. But then I noticed the free disk space on the new, larger drive: it was almost exactly the same as it was on the other disk... A disk that was half its size. So it looks as if I've copied the files across incorrectly and it's copied some of the filesystem metadata along with it. Tools like du and Disk Usage Analyzer come back with the correct figures. Things that look at the partition (and not the files) seem to think the drive is 120GB I've been using this drive for a week now so it's way out of sync with the old SSD so dumping the data and starting again isn't a job that fills me with joy but two questions: Is there a way to fix my filesystem so it knows what it's really on about? fsck e2fsck and badblocks all seem to be able to scan it without finding a problem with it. If I do plug my old SSD back in, copy the data off my PCI-E on to it and then copy it back onto a fresh filesystem (eg juggle the data around), what's the best way of doing that? I obviously want to keep all the permissions and softlinks where they are.

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• My new hard drive won't automount on boot

  - by user518

  I installed a new hard drive right before installing the new Ubuntu 11.10 by reformatting, not upgrading. I was able to mount my drive, and partition it. It's a 1TB, and I was able to transfer all of my music, and videos to it. For some reason, it won't mount on boot, and I can't figure out how to manually mount it afterwards either. Here's my current /etc/fstab: # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # proc /proc proc nodev,noexec,nosuid 0 0 # / was on /dev/sda1 during installation UUID=e0fbdf09-f9a0-4336-bac3-ba4dc6cfbcc0 / ext4 errors=remount-ro,user_xattr 0 1 # swap was on /dev/sda5 during installation UUID=adf15180-c84c-4309-bc9f-085fd7464f89 none swap sw 0 0 /dev/sdc1 /media/sdc1 ext4 defaults 0 0 The last line is what I added for my hard drive. Here's the output from sudo lshw -C disk: % sudo lshw -C disk ~ *-disk:0 description: ATA Disk product: ST3250310AS vendor: Seagate physical id: 0 bus info: scsi@2:0.0.0 logical name: /dev/sda version: 3.AD serial: 6RYBF2QE size: 232GiB (250GB) capabilities: partitioned partitioned:dos configuration: ansiversion=5 signature=000da204 *-cdrom description: DVD-RAM writer product: DVD+-RW DH-16A6S vendor: PLDS physical id: 0.0.0 bus info: scsi@4:0.0.0 logical name: /dev/cdrom logical name: /dev/cdrw logical name: /dev/dvd logical name: /dev/dvdrw logical name: /dev/scd0 logical name: /dev/sr0 version: YD11 capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram configuration: ansiversion=5 status=nodisc

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• ubuntu boots only with usb

  - by klimat

  Just installed Ubuntu 11.04. But it boots only from usb. Seems like I didn't pay attention during selecting boot device. sudo fdisk -l [sudo] password for klim: Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x000177e1 Device Boot Start End Blocks Id System /dev/sda1 1 60045 482302976 83 Linux /dev/sda2 60045 60802 6080513 5 Extended Partition 2 does not start on physical sector boundary. /dev/sda5 60045 60802 6080512 82 Linux swap / Solaris Disk /dev/sdb: 4004 MB, 4004511744 bytes 124 heads, 62 sectors/track, 1017 cylinders Units = cylinders of 7688 * 512 = 3936256 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000eee1a Device Boot Start End Blocks Id System /dev/sdb1 * 1 1017 3909317 b W95 FAT32 grub updating or another "grub" operations don't work as I've tried. Can I just copy whole boot folder from usb to HD or smth like that? Any kind of help is appreciated. Apologize for my newbie skills.

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• Can't mount my USB Drive

  - by user996056

  ~> sudo mount /dev/sdb1 /media/Disk Did not find any restart pages in $LogFile and it was not empty. The file system wasn't safely closed on Windows. Fixing. I have a USB Hard Disk and Windows can't detect it. So I tried to open it up on Ubuntu using gparted. Gparted detects the NTFS partition, so everything seems to be fine (note, though, that the total size of the files in this disk is over 1 TB). I tried to mount it using: sudo mount /dev/sdb1 /media/Disk But I got: Did not find any restart pages in $LogFile and it was not empty. The file system wasn't safely closed on Windows. Fixing. Then, the process just sits there blinking. Any ideas on how to fix it? It's taking forever ( 10 minutes), should I wait or cancel it and do something else? Thank you in advance.

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• Mounting a new hard drive (sda1) to my existing filesystem

  - by shank22

  I tried to read some posts regarding mounting a new hard drive, but I am facing some problem. My new hard drive is sda1. The output of sudo fdisk -l is: sudo fdisk -l Disk /dev/sdb: 999.7 GB, 999653638144 bytes 255 heads, 63 sectors/track, 121534 cylinders, total 1952448512 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: 0x00016485 Device Boot Start End Blocks Id System /dev/sdb1 * 2048 1935822847 967910400 83 Linux /dev/sdb2 1935824894 1952446463 8310785 5 Extended /dev/sdb5 1935824896 1952446463 8310784 82 Linux swap / Solaris Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x78dbcdc1 Device Boot Start End Blocks Id System /dev/sda1 2048 1953521663 976759808 7 HPFS/NTFS/exFAT What should be done to add this new sda1 hard drive on booting up? What should be added in the /etc/fstab file? I have not performed any partition on the new sda1 drive. I need help on how to proceed from scratch and can't afford to take any risk. Please help!

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• ??OSW (OSWatcher Black Box) ????

  - by Feng

     OSWatcher Black Box, ??OSW,?oracle???????????????,?????OS??????????OS??????????,??CPU/Memory/Swap/Network IO/Disk IO?????? +++ ????????OSW? OSW?????????,????????????????,???mrtg, cacti, sar, nmon, enterprise manger grid control. ????OSW?????: 1. ???????,???????2. ???????,????CPU,???????????3. ???????,????????????????????????OS? ???????OS???,??OS?????,?????????????;??????????????????????,???????. ???????,????????:?????????,??????????,????????????(root cause),?????????????????????????,OSW??????,??????: 1. ??????????OS??????????????????????????OSW??,?????????OS??,??????DB/???? 2. ??ORACLE Database Performance???,?????????????OS??????OS?????????????Swapping,???????????????,?????????,???AWR?????????latch/mutex?????? 3. ??????????????AWR??????????,top5??????????;?CPU,??,Swap, Disk IO?????????????OSW??????????,????????????????????????OSW???,??????????????? 4. ?????ORA-04030?????CJQ0, P00X, J00X?????????,???????OSW,???????????????????OS????????? 5. ????server process??hung?,??????OSW????????????????suspend???,?????????CPU/Memory? 6. ??Listener hung???,?????OSW??????????????? 7. Login Storm??:????????????,????,????ASH,AWR????????????????OSW?ps?????,??????, oracle ?server process????????? ???,OSW????????????????????OS?????????????,??????DBA???OSW??????????????OSW,????DB Performance????,????????OSW???? +++ ?????OSW??????: 1. ??????????????,???????,???????? 2. OSW???????? OSW??????????????OS???????,??ps, vmstat, netstat, mpstat, top;????????????????? ?????????CPU, Disk IO, Disk Space, Memory;???????????????,??????????????????????????,??OSW????????:?????????,CPU????90%??;???free space???????????????????????????,??OSW????????? +++ ????????UNIX/LINUX???/??OSW: 1. ???301137.1???OSW 2. ????????(/tmp??),??????????root?? $ tar xvf osw.tar 3. ?? $ nohup ./startOSWbb.sh 60 48 gzip & ????????,??OSW,????60???????,???????48?????(??????????),???????gzip?????? 4. ????? $ ./stopOSWbb.sh ?????????archive???? ????????????????????OSW???????,???????

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• How to Reduce the Size of Your WinSXS Folder on Windows 7 or 8

  - by Chris Hoffman

  The WinSXS folder at C:\Windows\WinSXS is massive and continues to grow the longer you have Windows installed. This folder builds up unnecessary files over time, such as old versions of system components. This folder also contains files for uninstalled, disabled Windows components. Even if you don’t have a Windows component installed, it will be present in your WinSXS folder, taking up space. Why the WinSXS Folder Gets to Big The WinSXS folder contains all Windows system components. In fact, component files elsewhere in Windows are just links to files contained in the WinSXS folder. The WinSXS folder contains every operating system file. When Windows installs updates, it drops the new Windows component in the WinSXS folder and keeps the old component in the WinSXS folder. This means that every Windows Update you install increases the size of your WinSXS folder. This allows you to uninstall operating system updates from the Control Panel, which can be useful in the case of a buggy update — but it’s a feature that’s rarely used. Windows 7 dealt with this by including a feature that allows Windows to clean up old Windows update files after you install a new Windows service pack. The idea was that the system could be cleaned up regularly along with service packs. However, Windows 7 only saw one service pack — Service Pack 1 — released in 2010. Microsoft has no intention of launching another. This means that, for more than three years, Windows update uninstallation files have been building up on Windows 7 systems and couldn’t be easily removed. Clean Up Update Files To fix this problem, Microsoft recently backported a feature from Windows 8 to Windows 7. They did this without much fanfare — it was rolled out in a typical minor operating system update, the kind that don’t generally add new features. To clean up such update files, open the Disk Cleanup wizard (tap the Windows key, type “disk cleanup” into the Start menu, and press Enter). Click the Clean up System Files button, enable the Windows Update Cleanup option and click OK. If you’ve been using your Windows 7 system for a few years, you’ll likely be able to free several gigabytes of space. The next time you reboot after doing this, Windows will take a few minutes to clean up system files before you can log in and use your desktop. If you don’t see this feature in the Disk Cleanup window, you’re likely behind on your updates — install the latest updates from Windows Update. Windows 8 and 8.1 include built-in features that do this automatically. In fact, there’s a StartComponentCleanup scheduled task included with Windows that will automatically run in the background, cleaning up components 30 days after you’ve installed them. This 30-day period gives you time to uninstall an update if it causes problems. If you’d like to manually clean up updates, you can also use the Windows Update Cleanup option in the Disk Usage window, just as you can on Windows 7. (To open it, tap the Windows key, type “disk cleanup” to perform a search, and click the “Free up disk space by removing unnecessary files” shortcut that appears.) Windows 8.1 gives you more options, allowing you to forcibly remove all previous versions of uninstalled components, even ones that haven’t been around for more than 30 days. These commands must be run in an elevated Command Prompt — in other words, start the Command Prompt window as Administrator. For example, the following command will uninstall all previous versions of components without the scheduled task’s 30-day grace period: DISM.exe /online /Cleanup-Image /StartComponentCleanup The following command will remove files needed for uninstallation of service packs. You won’t be able to uninstall any currently installed service packs after running this command: DISM.exe /online /Cleanup-Image /SPSuperseded The following command will remove all old versions of every component. You won’t be able to uninstall any currently installed service packs or updates after this completes: DISM.exe /online /Cleanup-Image /StartComponentCleanup /ResetBase Remove Features on Demand Modern versions of Windows allow you to enable or disable Windows features on demand. You’ll find a list of these features in the Windows Features window you can access from the Control Panel. Even features you don’t have installed — that is, the features you see unchecked in this window — are stored on your hard drive in your WinSXS folder. If you choose to install them, they’ll be made available from your WinSXS folder. This means you won’t have to download anything or provide Windows installation media to install these features. However, these features take up space. While this shouldn’t matter on typical computers, users with extremely low amounts of storage or Windows server administrators who want to slim their Windows installs down to the smallest possible set of system files may want to get these files off their hard drives. For this reason, Windows 8 added a new option that allows you to remove these uninstalled components from the WinSXS folder entirely, freeing up space. If you choose to install the removed components later, Windows will prompt you to download the component files from Microsoft. To do this, open a Command Prompt window as Administrator. Use the following command to see the features available to you: DISM.exe /Online /English /Get-Features /Format:Table You’ll see a table of feature names and their states. To remove a feature from your system, you’d use the following command, replacing NAME with the name of the feature you want to remove. You can get the feature name you need from the table above. DISM.exe /Online /Disable-Feature /featurename:NAME /Remove If you run the /GetFeatures command again, you’ll now see that the feature has a status of “Disabled with Payload Removed” instead of just “Disabled.” That’s how you know it’s not taking up space on your computer’s hard drive. If you’re trying to slim down a Windows system as much as possible, be sure to check out our lists of ways to free up disk space on Windows and reduce the space used by system files.     

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• .NET Memory Leak: XslCompiledTransform and “leaked” dynamic assemblies

  - by Latest Microsoft Blogs

  I have written before about high memory usage caused by improper usage of XmlSerializer objects both in a case study and in a debugging lab .  The problem there was that every time you create a new XmlSerializer object with a non-default constructor Read More......(read more)

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• Reducing Oracle LOB Memory Use in PHP, or Paul's Lesson Applied to Oracle

  - by christopher.jones

  Paul Reinheimer's PHP memory pro tip shows how re-assigning a value to a variable doesn't release the original value until the new data is ready. With large data lengths, this unnecessarily increases the peak memory usage of the application. In Oracle you might come across this situation when dealing with LOBS. Here's an example that selects an entire LOB into PHP's memory. I see this being done all the time, not that that is an excuse to code in this style. The alternative is to remove OCI_RETURN_LOBS to return a LOB locator which can be accessed chunkwise with LOB->read(). In this memory usage example, I threw some CLOB rows into a table. Each CLOB was about 1.5M. The fetching code looked like: $s = oci_parse ($c, 'SELECT CLOBDATA FROM CTAB'); oci_execute($s); echo "Start Current :" . memory_get_usage() . "\n"; echo "Start Peak : " .memory_get_peak_usage() . "\n"; while(($r = oci_fetch_array($s, OCI_RETURN_LOBS)) !== false) { echo "Current :" . memory_get_usage() . "\n"; echo "Peak : " . memory_get_peak_usage() . "\n"; // var_dump(substr($r['CLOBDATA'],0,10)); // do something with the LOB // unset($r); } echo "End Current :" . memory_get_usage() . "\n"; echo "End Peak : " . memory_get_peak_usage() . "\n"; Without "unset" in loop, $r retains the current data value while new data is fetched: Start Current : 345300 Start Peak : 353676 Current : 1908092 Peak : 2958720 Current : 1908092 Peak : 4520972 End Current : 345668 End Peak : 4520972 When I uncommented the "unset" line in the loop, PHP's peak memory usage is much lower: Start Current : 345376 Start Peak : 353676 Current : 1908168 Peak : 2958796 Current : 1908168 Peak : 2959108 End Current : 345744 End Peak : 2959108 Even if you are using LOB->read(), unsetting variables in this manner will reduce the PHP program's peak memory usage. With LOBS in Oracle DB there is also DB memory use to consider. Using LOB->free() is worthwhile for locators. Importantly, the OCI8 1.4.1 extension (from PECL or included in PHP 5.3.2) has a LOB fix to free up Oracle's locators earlier. For long running scripts using lots of LOBS, upgrading to OCI8 1.4.1 is recommended.

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• Advanced TSQL Tuning: Why Internals Knowledge Matters

  - by Paul White

  There is much more to query tuning than reducing logical reads and adding covering nonclustered indexes.  Query tuning is not complete as soon as the query returns results quickly in the development or test environments.  In production, your query will compete for memory, CPU, locks, I/O and other resources on the server.  Today’s entry looks at some tuning considerations that are often overlooked, and shows how deep internals knowledge can help you write better TSQL. As always, we’ll need some example data.  In fact, we are going to use three tables today, each of which is structured like this: Each table has 50,000 rows made up of an INTEGER id column and a padding column containing 3,999 characters in every row.  The only difference between the three tables is in the type of the padding column: the first table uses CHAR(3999), the second uses VARCHAR(MAX), and the third uses the deprecated TEXT type.  A script to create a database with the three tables and load the sample data follows: USE master; GO IF DB_ID('SortTest') IS NOT NULL DROP DATABASE SortTest; GO CREATE DATABASE SortTest COLLATE LATIN1_GENERAL_BIN; GO ALTER DATABASE SortTest MODIFY FILE ( NAME = 'SortTest', SIZE = 3GB, MAXSIZE = 3GB ); GO ALTER DATABASE SortTest MODIFY FILE ( NAME = 'SortTest_log', SIZE = 256MB, MAXSIZE = 1GB, FILEGROWTH = 128MB ); GO ALTER DATABASE SortTest SET ALLOW_SNAPSHOT_ISOLATION OFF ; ALTER DATABASE SortTest SET AUTO_CLOSE OFF ; ALTER DATABASE SortTest SET AUTO_CREATE_STATISTICS ON ; ALTER DATABASE SortTest SET AUTO_SHRINK OFF ; ALTER DATABASE SortTest SET AUTO_UPDATE_STATISTICS ON ; ALTER DATABASE SortTest SET AUTO_UPDATE_STATISTICS_ASYNC ON ; ALTER DATABASE SortTest SET PARAMETERIZATION SIMPLE ; ALTER DATABASE SortTest SET READ_COMMITTED_SNAPSHOT OFF ; ALTER DATABASE SortTest SET MULTI_USER ; ALTER DATABASE SortTest SET RECOVERY SIMPLE ; USE SortTest; GO CREATE TABLE dbo.TestCHAR ( id INTEGER IDENTITY (1,1) NOT NULL, padding CHAR(3999) NOT NULL,   CONSTRAINT [PK dbo.TestCHAR (id)] PRIMARY KEY CLUSTERED (id), ) ; CREATE TABLE dbo.TestMAX ( id INTEGER IDENTITY (1,1) NOT NULL, padding VARCHAR(MAX) NOT NULL,   CONSTRAINT [PK dbo.TestMAX (id)] PRIMARY KEY CLUSTERED (id), ) ; CREATE TABLE dbo.TestTEXT ( id INTEGER IDENTITY (1,1) NOT NULL, padding TEXT NOT NULL,   CONSTRAINT [PK dbo.TestTEXT (id)] PRIMARY KEY CLUSTERED (id), ) ; -- ============= -- Load TestCHAR (about 3s) -- ============= INSERT INTO dbo.TestCHAR WITH (TABLOCKX) ( padding ) SELECT padding = REPLICATE(CHAR(65 + (Data.n % 26)), 3999) FROM ( SELECT TOP (50000) n = ROW_NUMBER() OVER (ORDER BY (SELECT 0)) - 1 FROM master.sys.columns C1, master.sys.columns C2, master.sys.columns C3 ORDER BY n ASC ) AS Data ORDER BY Data.n ASC ; -- ============ -- Load TestMAX (about 3s) -- ============ INSERT INTO dbo.TestMAX WITH (TABLOCKX) ( padding ) SELECT CONVERT(VARCHAR(MAX), padding) FROM dbo.TestCHAR ORDER BY id ; -- ============= -- Load TestTEXT (about 5s) -- ============= INSERT INTO dbo.TestTEXT WITH (TABLOCKX) ( padding ) SELECT CONVERT(TEXT, padding) FROM dbo.TestCHAR ORDER BY id ; -- ========== -- Space used -- ========== -- EXECUTE sys.sp_spaceused @objname = 'dbo.TestCHAR'; EXECUTE sys.sp_spaceused @objname = 'dbo.TestMAX'; EXECUTE sys.sp_spaceused @objname = 'dbo.TestTEXT'; ; CHECKPOINT ; That takes around 15 seconds to run, and shows the space allocated to each table in its output: To illustrate the points I want to make today, the example task we are going to set ourselves is to return a random set of 150 rows from each table.  The basic shape of the test query is the same for each of the three test tables: SELECT TOP (150) T.id, T.padding FROM dbo.Test AS T ORDER BY NEWID() OPTION (MAXDOP 1) ; Test 1 – CHAR(3999) Running the template query shown above using the TestCHAR table as the target, we find that the query takes around 5 seconds to return its results.  This seems slow, considering that the table only has 50,000 rows.  Working on the assumption that generating a GUID for each row is a CPU-intensive operation, we might try enabling parallelism to see if that speeds up the response time.  Running the query again (but without the MAXDOP 1 hint) on a machine with eight logical processors, the query now takes 10 seconds to execute – twice as long as when run serially. Rather than attempting further guesses at the cause of the slowness, let’s go back to serial execution and add some monitoring.  The script below monitors STATISTICS IO output and the amount of tempdb used by the test query.  We will also run a Profiler trace to capture any warnings generated during query execution. DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) TC.id, TC.padding FROM dbo.TestCHAR AS TC ORDER BY NEWID() OPTION (MAXDOP 1) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; Let’s take a closer look at the statistics and query plan generated from this: Following the flow of the data from right to left, we see the expected 50,000 rows emerging from the Clustered Index Scan, with a total estimated size of around 191MB.  The Compute Scalar adds a column containing a random GUID (generated from the NEWID() function call) for each row.  With this extra column in place, the size of the data arriving at the Sort operator is estimated to be 192MB. Sort is a blocking operator – it has to examine all of the rows on its input before it can produce its first row of output (the last row received might sort first).  This characteristic means that Sort requires a memory grant – memory allocated for the query’s use by SQL Server just before execution starts.  In this case, the Sort is the only memory-consuming operator in the plan, so it has access to the full 243MB (248,696KB) of memory reserved by SQL Server for this query execution. Notice that the memory grant is significantly larger than the expected size of the data to be sorted.  SQL Server uses a number of techniques to speed up sorting, some of which sacrifice size for comparison speed.  Sorts typically require a very large number of comparisons, so this is usually a very effective optimization.  One of the drawbacks is that it is not possible to exactly predict the sort space needed, as it depends on the data itself.  SQL Server takes an educated guess based on data types, sizes, and the number of rows expected, but the algorithm is not perfect. In spite of the large memory grant, the Profiler trace shows a Sort Warning event (indicating that the sort ran out of memory), and the tempdb usage monitor shows that 195MB of tempdb space was used – all of that for system use.  The 195MB represents physical write activity on tempdb, because SQL Server strictly enforces memory grants – a query cannot ‘cheat’ and effectively gain extra memory by spilling to tempdb pages that reside in memory.  Anyway, the key point here is that it takes a while to write 195MB to disk, and this is the main reason that the query takes 5 seconds overall. If you are wondering why using parallelism made the problem worse, consider that eight threads of execution result in eight concurrent partial sorts, each receiving one eighth of the memory grant.  The eight sorts all spilled to tempdb, resulting in inefficiencies as the spilled sorts competed for disk resources.  More importantly, there are specific problems at the point where the eight partial results are combined, but I’ll cover that in a future post. CHAR(3999) Performance Summary: 5 seconds elapsed time 243MB memory grant 195MB tempdb usage 192MB estimated sort set 25,043 logical reads Sort Warning Test 2 – VARCHAR(MAX) We’ll now run exactly the same test (with the additional monitoring) on the table using a VARCHAR(MAX) padding column: DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) TM.id, TM.padding FROM dbo.TestMAX AS TM ORDER BY NEWID() OPTION (MAXDOP 1) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; This time the query takes around 8 seconds to complete (3 seconds longer than Test 1).  Notice that the estimated row and data sizes are very slightly larger, and the overall memory grant has also increased very slightly to 245MB.  The most marked difference is in the amount of tempdb space used – this query wrote almost 391MB of sort run data to the physical tempdb file.  Don’t draw any general conclusions about VARCHAR(MAX) versus CHAR from this – I chose the length of the data specifically to expose this edge case.  In most cases, VARCHAR(MAX) performs very similarly to CHAR – I just wanted to make test 2 a bit more exciting. MAX Performance Summary: 8 seconds elapsed time 245MB memory grant 391MB tempdb usage 193MB estimated sort set 25,043 logical reads Sort warning Test 3 – TEXT The same test again, but using the deprecated TEXT data type for the padding column: DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) TT.id, TT.padding FROM dbo.TestTEXT AS TT ORDER BY NEWID() OPTION (MAXDOP 1, RECOMPILE) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; This time the query runs in 500ms.  If you look at the metrics we have been checking so far, it’s not hard to understand why: TEXT Performance Summary: 0.5 seconds elapsed time 9MB memory grant 5MB tempdb usage 5MB estimated sort set 207 logical reads 596 LOB logical reads Sort warning SQL Server’s memory grant algorithm still underestimates the memory needed to perform the sorting operation, but the size of the data to sort is so much smaller (5MB versus 193MB previously) that the spilled sort doesn’t matter very much.  Why is the data size so much smaller?  The query still produces the correct results – including the large amount of data held in the padding column – so what magic is being performed here? TEXT versus MAX Storage The answer lies in how columns of the TEXT data type are stored.  By default, TEXT data is stored off-row in separate LOB pages – which explains why this is the first query we have seen that records LOB logical reads in its STATISTICS IO output.  You may recall from my last post that LOB data leaves an in-row pointer to the separate storage structure holding the LOB data. SQL Server can see that the full LOB value is not required by the query plan until results are returned, so instead of passing the full LOB value down the plan from the Clustered Index Scan, it passes the small in-row structure instead.  SQL Server estimates that each row coming from the scan will be 79 bytes long – 11 bytes for row overhead, 4 bytes for the integer id column, and 64 bytes for the LOB pointer (in fact the pointer is rather smaller – usually 16 bytes – but the details of that don’t really matter right now). OK, so this query is much more efficient because it is sorting a very much smaller data set – SQL Server delays retrieving the LOB data itself until after the Sort starts producing its 150 rows.  The question that normally arises at this point is: Why doesn’t SQL Server use the same trick when the padding column is defined as VARCHAR(MAX)? The answer is connected with the fact that if the actual size of the VARCHAR(MAX) data is 8000 bytes or less, it is usually stored in-row in exactly the same way as for a VARCHAR(8000) column – MAX data only moves off-row into LOB storage when it exceeds 8000 bytes.  The default behaviour of the TEXT type is to be stored off-row by default, unless the ‘text in row’ table option is set suitably and there is room on the page.  There is an analogous (but opposite) setting to control the storage of MAX data – the ‘large value types out of row’ table option.  By enabling this option for a table, MAX data will be stored off-row (in a LOB structure) instead of in-row.  SQL Server Books Online has good coverage of both options in the topic In Row Data. The MAXOOR Table The essential difference, then, is that MAX defaults to in-row storage, and TEXT defaults to off-row (LOB) storage.  You might be thinking that we could get the same benefits seen for the TEXT data type by storing the VARCHAR(MAX) values off row – so let’s look at that option now.  This script creates a fourth table, with the VARCHAR(MAX) data stored off-row in LOB pages: CREATE TABLE dbo.TestMAXOOR ( id INTEGER IDENTITY (1,1) NOT NULL, padding VARCHAR(MAX) NOT NULL,   CONSTRAINT [PK dbo.TestMAXOOR (id)] PRIMARY KEY CLUSTERED (id), ) ; EXECUTE sys.sp_tableoption @TableNamePattern = N'dbo.TestMAXOOR', @OptionName = 'large value types out of row', @OptionValue = 'true' ; SELECT large_value_types_out_of_row FROM sys.tables WHERE [schema_id] = SCHEMA_ID(N'dbo') AND name = N'TestMAXOOR' ; INSERT INTO dbo.TestMAXOOR WITH (TABLOCKX) ( padding ) SELECT SPACE(0) FROM dbo.TestCHAR ORDER BY id ; UPDATE TM WITH (TABLOCK) SET padding.WRITE (TC.padding, NULL, NULL) FROM dbo.TestMAXOOR AS TM JOIN dbo.TestCHAR AS TC ON TC.id = TM.id ; EXECUTE sys.sp_spaceused @objname = 'dbo.TestMAXOOR' ; CHECKPOINT ; Test 4 – MAXOOR We can now re-run our test on the MAXOOR (MAX out of row) table: DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) MO.id, MO.padding FROM dbo.TestMAXOOR AS MO ORDER BY NEWID() OPTION (MAXDOP 1, RECOMPILE) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; TEXT Performance Summary: 0.3 seconds elapsed time 245MB memory grant 0MB tempdb usage 193MB estimated sort set 207 logical reads 446 LOB logical reads No sort warning The query runs very quickly – slightly faster than Test 3, and without spilling the sort to tempdb (there is no sort warning in the trace, and the monitoring query shows zero tempdb usage by this query).  SQL Server is passing the in-row pointer structure down the plan and only looking up the LOB value on the output side of the sort. The Hidden Problem There is still a huge problem with this query though – it requires a 245MB memory grant.  No wonder the sort doesn’t spill to tempdb now – 245MB is about 20 times more memory than this query actually requires to sort 50,000 records containing LOB data pointers.  Notice that the estimated row and data sizes in the plan are the same as in test 2 (where the MAX data was stored in-row). The optimizer assumes that MAX data is stored in-row, regardless of the sp_tableoption setting ‘large value types out of row’.  Why?  Because this option is dynamic – changing it does not immediately force all MAX data in the table in-row or off-row, only when data is added or actually changed.  SQL Server does not keep statistics to show how much MAX or TEXT data is currently in-row, and how much is stored in LOB pages.  This is an annoying limitation, and one which I hope will be addressed in a future version of the product. So why should we worry about this?  Excessive memory grants reduce concurrency and may result in queries waiting on the RESOURCE_SEMAPHORE wait type while they wait for memory they do not need.  245MB is an awful lot of memory, especially on 32-bit versions where memory grants cannot use AWE-mapped memory.  Even on a 64-bit server with plenty of memory, do you really want a single query to consume 0.25GB of memory unnecessarily?  That’s 32,000 8KB pages that might be put to much better use. The Solution The answer is not to use the TEXT data type for the padding column.  That solution happens to have better performance characteristics for this specific query, but it still results in a spilled sort, and it is hard to recommend the use of a data type which is scheduled for removal.  I hope it is clear to you that the fundamental problem here is that SQL Server sorts the whole set arriving at a Sort operator.  Clearly, it is not efficient to sort the whole table in memory just to return 150 rows in a random order. The TEXT example was more efficient because it dramatically reduced the size of the set that needed to be sorted.  We can do the same thing by selecting 150 unique keys from the table at random (sorting by NEWID() for example) and only then retrieving the large padding column values for just the 150 rows we need.  The following script implements that idea for all four tables: SET STATISTICS IO ON ; WITH TestTable AS ( SELECT * FROM dbo.TestCHAR ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id = ANY (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; WITH TestTable AS ( SELECT * FROM dbo.TestMAX ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id IN (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; WITH TestTable AS ( SELECT * FROM dbo.TestTEXT ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id IN (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; WITH TestTable AS ( SELECT * FROM dbo.TestMAXOOR ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id IN (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; SET STATISTICS IO OFF ; All four queries now return results in much less than a second, with memory grants between 6 and 12MB, and without spilling to tempdb.  The small remaining inefficiency is in reading the id column values from the clustered primary key index.  As a clustered index, it contains all the in-row data at its leaf.  The CHAR and VARCHAR(MAX) tables store the padding column in-row, so id values are separated by a 3999-character column, plus row overhead.  The TEXT and MAXOOR tables store the padding values off-row, so id values in the clustered index leaf are separated by the much-smaller off-row pointer structure.  This difference is reflected in the number of logical page reads performed by the four queries: Table 'TestCHAR' logical reads 25511 lob logical reads 000 Table 'TestMAX'. logical reads 25511 lob logical reads 000 Table 'TestTEXT' logical reads 00412 lob logical reads 597 Table 'TestMAXOOR' logical reads 00413 lob logical reads 446 We can increase the density of the id values by creating a separate nonclustered index on the id column only.  This is the same key as the clustered index, of course, but the nonclustered index will not include the rest of the in-row column data. CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestCHAR (id); CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestMAX (id); CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestTEXT (id); CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestMAXOOR (id); The four queries can now use the very dense nonclustered index to quickly scan the id values, sort them by NEWID(), select the 150 ids we want, and then look up the padding data.  The logical reads with the new indexes in place are: Table 'TestCHAR' logical reads 835 lob logical reads 0 Table 'TestMAX' logical reads 835 lob logical reads 0 Table 'TestTEXT' logical reads 686 lob logical reads 597 Table 'TestMAXOOR' logical reads 686 lob logical reads 448 With the new index, all four queries use the same query plan (click to enlarge): Performance Summary: 0.3 seconds elapsed time 6MB memory grant 0MB tempdb usage 1MB sort set 835 logical reads (CHAR, MAX) 686 logical reads (TEXT, MAXOOR) 597 LOB logical reads (TEXT) 448 LOB logical reads (MAXOOR) No sort warning I’ll leave it as an exercise for the reader to work out why trying to eliminate the Key Lookup by adding the padding column to the new nonclustered indexes would be a daft idea Conclusion This post is not about tuning queries that access columns containing big strings.  It isn’t about the internal differences between TEXT and MAX data types either.  It isn’t even about the cool use of UPDATE .WRITE used in the MAXOOR table load.  No, this post is about something else: Many developers might not have tuned our starting example query at all – 5 seconds isn’t that bad, and the original query plan looks reasonable at first glance.  Perhaps the NEWID() function would have been blamed for ‘just being slow’ – who knows.  5 seconds isn’t awful – unless your users expect sub-second responses – but using 250MB of memory and writing 200MB to tempdb certainly is!  If ten sessions ran that query at the same time in production that’s 2.5GB of memory usage and 2GB hitting tempdb.  Of course, not all queries can be rewritten to avoid large memory grants and sort spills using the key-lookup technique in this post, but that’s not the point either. The point of this post is that a basic understanding of execution plans is not enough.  Tuning for logical reads and adding covering indexes is not enough.  If you want to produce high-quality, scalable TSQL that won’t get you paged as soon as it hits production, you need a deep understanding of execution plans, and as much accurate, deep knowledge about SQL Server as you can lay your hands on.  The advanced database developer has a wide range of tools to use in writing queries that perform well in a range of circumstances. By the way, the examples in this post were written for SQL Server 2008.  They will run on 2005 and demonstrate the same principles, but you won’t get the same figures I did because 2005 had a rather nasty bug in the Top N Sort operator.  Fair warning: if you do decide to run the scripts on a 2005 instance (particularly the parallel query) do it before you head out for lunch… This post is dedicated to the people of Christchurch, New Zealand. © 2011 Paul White email: @[email protected] twitter: @SQL_Kiwi

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• Announcing Entity Framework Code-First (CTP 5 release)

  In this article, Scott provides a detailed coverage of Entity Framework Code-First CTP 5 release and the features included with the build. He begins with the steps required to install EF Code First. Scott then examines the usage of EF Code First to create a model layer for the Northwind sample database in a series of steps. Towards the end of the article, Scott examines the usage of UI Validation and few addtional EF Code First Improvements shipped with CTP 5.

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• No root file system is defined error after installation

  - by LearnCode

  I installed ubuntu through Wubi and once i rebooted I get no root file system defined error. here's the output of the boot_info_script.Could anyone point me out where the error is. Boot Info Script 0.60 from 17 May 2011 ============================= Boot Info Summary: =============================== => Windows is installed in the MBR of /dev/sda. => Windows is installed in the MBR of /dev/sdb. sda1: __________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Windows 7 Boot files: /bootmgr /Boot/BCD /Windows/System32/winload.exe /ntldr /ntdetect.com /wubildr /ubuntu/winboot/wubildr /wubildr.mbr /ubuntu/winboot/wubildr.mbr /ubuntu/disks/root.disk /ubuntu/disks/swap.disk sda1/Wubi: _____________________________________________________________________ File system: Boot sector type: Unknown Boot sector info: Mounting failed: mount: unknown filesystem type '' sda2: __________________________________________________________________________ File system: vfat Boot sector type: Unknown Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files: /boot.ini /ntldr /NTDETECT.COM sdb1: __________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files: ============================ Drive/Partition Info: ============================= Drive: sda _____________________________________________________________________ Disk /dev/sda: 160.0 GB, 160041885696 bytes 240 heads, 63 sectors/track, 20673 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start Sector End Sector # of Sectors Id System /dev/sda1 * 63 301,250,879 301,250,817 7 NTFS / exFAT / HPFS /dev/sda2 301,250,943 312,575,759 11,324,817 c W95 FAT32 (LBA) GUID Partition Table detected, but does not seem to be used. Partition Start Sector End Sector # of Sectors System /dev/sda1 323,465,741,313,502,988275,962,973,585-323,465,465,350,529,402 - /dev/sda2 242,728,591,638,290,720578,721,383,108,845,578335,992,791,470,554,859 - /dev/sda3 1,827,498,311,425,204,2562,091,935,274,843,009,907264,436,963,417,805,652 - /dev/sda4 579,711,218,081,401,3572,006,665,459,744,645,1521,426,954,241,663,243,796 - /dev/sda11 270,286,346,402,038,1183,786,543,326,404,525,9543,516,256,980,002,487,837 - /dev/sda12 4,179,681,002,230,769,6684,179,389,374,010,033,387-291,628,220,736,280 - /dev/sda13 232,556,480,979,456,1311,160,152,593,793,119,235927,596,112,813,663,105 - /dev/sda14 98,342,784,050,266,9183,691,264,578,843,725,1953,592,921,794,793,458,278 - /dev/sda15 2,307,845,219,957,882,4961,850,841,032,955,276,350-457,004,187,002,606,145 - /dev/sda16 512,592,046,878,946,497368,458,231,024,779,444-144,133,815,854,167,052 - /dev/sda17 2,504,135,232,870,384,3923,665,087,872,719,320,8291,160,952,639,848,936,438 - /dev/sda18 3,783,181,605,270,691,304122,034,509,624,708,942-3,661,147,095,645,982,361 - /dev/sda19 3,519,661,520,275,829,5122,376,243,094,723,723,587-1,143,418,425,552,105,924 - /dev/sda20 3,867,920,076,859,0744,494,691,111,933,625,1044,490,823,191,856,766,031 - /dev/sda21 1,500,144,061,909,253,7612,511,182,033,846,676,3401,011,037,971,937,422,580 - /dev/sda22 13,035,625,499,900,0062,360,168,613,941,394,9472,347,132,988,441,494,942 - /dev/sda23 4,228,978,682,068,599,48813,159,423,631,648,263-4,215,819,258,436,951,224 - /dev/sda24 3,695,955,742,872,046,9084,561,928,726,501,845,776865,972,983,629,798,869 - /dev/sda25 1,297,460,286,683,948,0461,444,350,486,339,417,957146,890,199,655,469,912 - /dev/sda26 1,228,858,248,533,131,831 0-1,228,858,248,533,131,830 - /dev/sda121 3,189,184,846,146,487,1461,849,820,258,006,914,852-1,339,364,588,139,572,293 - /dev/sda122 1,226,215,547,991,800,578389,781,518,734,546,300-836,434,029,257,254,277 - /dev/sda123 3,851,660,168,574,583,4654,046,215,657,583,031,556194,555,489,008,448,092 - /dev/sda124 1,197,460,980,174,153,341699,103,965,005,093,246-498,357,015,169,060,094 - Drive: sdb _____________________________________________________________________ Disk /dev/sdb: 750.2 GB, 750153367552 bytes 255 heads, 63 sectors/track, 91200 cylinders, total 1465143296 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start Sector End Sector # of Sectors Id System /dev/sdb1 2,048 1,465,143,295 1,465,141,248 7 NTFS / exFAT / HPFS "blkid" output: ________________________________________________________________ Device UUID TYPE LABEL /dev/loop0 iso9660 Ubuntu 11.04 amd64 /dev/loop1 squashfs /dev/sda1 E814B55B14B52E06 ntfs /dev/sda2 01CD-023B vfat HP_RECOVERY /dev/sdb1 7836F22A36F1E8D0 ntfs Elements ================================ Mount points: ================================= Device Mount_Point Type Options /dev/loop0 /cdrom iso9660 (ro,noatime) /dev/loop1 /rofs squashfs (ro,noatime) /dev/sdb1 /mnt fuseblk (rw,nosuid,nodev,allow_other,blksize=4096) ================================ sda2/boot.ini: ================================ -------------------------------------------------------------------------------- [boot loader] timeout=0 default=C:\CMDCONS\BOOTSECT.DAT [operating systems] multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect C:\CMDCONS\BOOTSECT.DAT="Microsoft Windows Recovery Console" /cmdcons -------------------------------------------------------------------------------- ======================== Unknown MBRs/Boot Sectors/etc: ======================== Unknown GPT Partiton Type c104043000e9b9040dff24b580010100 Unknown GPT Partiton Type 46313020746f20737461727420746865 Unknown GPT Partiton Type 65727920706172746974696f6e207761 Unknown GPT Partiton Type 727920706172746974696f6e0d0a0000 Unknown GPT Partiton Type 000f84e5f7668b162404e82804744066 Unknown GPT Partiton Type ce01e8dc038bfe66391624047505e8d9 Unknown GPT Partiton Type 0345086603f0e881030bd2740333d240 Unknown GPT Partiton Type bece01e8db0287fec645041266895508 Unknown GPT Partiton Type 01f60634010175078b363b01e854f5e8 Unknown GPT Partiton Type 313825740ffec03865107408fec03824 Unknown GPT Partiton Type 02f60634014074088bfdbece01e85101 Unknown GPT Partiton Type 263401f9e894f30f858ef4e8e201e8ec Unknown GPT Partiton Type f7e960f35245434f5645525966606633 Unknown GPT Partiton Type 660faf1e00106603dac3668b0e001066 Unknown GPT Partiton Type 8bfd386d04740583c710e2f6c36660c6 Unknown GPT Partiton Type 04ebf132c0b91000f3aac3bf0c04ebf3 Unknown GPT Partiton Type 02662bc1660fb71e0e02662bc366031e Unknown GPT Partiton Type f4b40ebb0700b901003c08751381ff25 Unknown GPT Partiton Type 534f465448494e4b90653f62011b0100 Unknown GPT Partiton Type 0b050900027777772e68702e636f6d00 Unknown GPT Partiton Type d441a0f5030003000ecb744a08bb3746 Unknown GPT Partiton Type f8579a116b4a7aa931cde97a4b9b5c09 Unknown GPT Partiton Type 7229990415b77c0a1970e7e824237a3a Unknown GPT Partiton Type afb6e34d6b4bd8c7c0eada19a9786cc3 Unknown BootLoader on sda1/Wubi 00000000 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000| * 00000200 Unknown BootLoader on sda2 00000000 e9 a7 00 52 45 43 4f 56 45 52 59 00 02 08 20 00 |...RECOVERY... .| 00000010 02 00 00 00 00 f8 00 00 3f 00 f0 00 7f b9 f4 11 |........?.......| 00000020 8c cd ac 00 1e 2b 00 00 00 00 00 00 02 00 00 00 |.....+..........| 00000030 01 00 06 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00000040 80 00 29 3b 02 cd 01 20 20 20 20 20 20 20 20 20 |..);... | 00000050 20 20 46 41 54 33 32 20 20 20 8b d0 c1 e2 02 80 | FAT32 ......| 00000060 e6 01 66 c1 e8 07 66 3b 46 f8 74 2a 66 89 46 f8 |..f...f;F.t*f.F.| 00000070 66 03 46 f4 66 0f b6 5e 28 80 e3 0f 74 0f 3a 5e |f.F.f..^(...t.:^| 00000080 10 0f 83 90 00 66 0f af 5e 24 66 03 c3 bb e0 07 |.....f..^$f.....| 00000090 b9 01 00 e8 cf 00 8b da 66 8b 87 00 7e 66 25 ff |........f...~f%.| 000000a0 ff ff 0f 66 3d f8 ff ff 0f c3 33 c9 8e d9 8e c1 |...f=.....3.....| 000000b0 8e d1 66 bc f4 7b 00 00 bd 00 7c 66 0f b6 46 10 |..f..{....|f..F.| 000000c0 66 f7 66 24 66 0f b7 56 0e 66 03 56 1c 66 89 56 |f.f$f..V.f.V.f.V| 000000d0 f4 66 03 c2 66 89 46 fc 66 c7 46 f8 ff ff ff ff |.f..f.F.f.F.....| 000000e0 66 8b 46 2c 66 50 e8 af 00 bb 70 00 b9 01 00 e8 |f.F,fP....p.....| 000000f0 73 00 bf 00 07 b1 0b be a9 7d f3 a6 74 2a 03 f9 |s........}..t*..| 00000100 83 c7 15 81 ff 00 09 72 ec 66 40 4a 75 db 66 58 |[email protected]| 00000110 e8 47 ff 72 cf be b4 7d ac 84 c0 74 09 b4 0e bb |.G.r...}...t....| 00000120 07 00 cd 10 eb f2 cd 19 66 58 ff 75 09 ff 75 0f |........fX.u..u.| 00000130 66 58 bb 00 20 66 83 f8 02 72 da 66 3d f8 ff ff |fX.. f...r.f=...| 00000140 0f 73 d2 66 50 e8 50 00 0f b6 4e 0d e8 16 00 c1 |.s.fP.P...N.....| 00000150 e1 05 03 d9 66 58 53 e8 00 ff 5b 72 d8 8a 56 40 |....fXS...[r..V@| 00000160 ea 00 00 00 20 66 60 66 6a 00 66 50 53 6a 00 66 |.... f`fj.fPSj.f| 00000170 68 10 00 01 00 8b f4 b8 00 42 8a 56 40 cd 13 be |h........B.V@...| 00000180 c7 7d 72 94 67 83 44 24 06 20 66 67 ff 44 24 08 |.}r.g.D$. fg.D$.| 00000190 e2 e3 83 c4 10 66 61 c3 66 48 66 48 66 0f b6 56 |.....fa.fHfHf..V| 000001a0 0d 66 f7 e2 66 03 46 fc c3 4e 54 4c 44 52 20 20 |.f..f.F..NTLDR | 000001b0 20 20 20 20 0d 0a 4e 6f 20 53 79 73 74 65 6d 20 | ..No System | 000001c0 44 69 73 6b 20 6f 72 0d 0a 44 69 73 6b 20 49 2f |Disk or..Disk I/| 000001d0 4f 20 65 72 72 6f 72 0d 0a 50 72 65 73 73 20 61 |O error..Press a| 000001e0 20 6b 65 79 20 74 6f 20 72 65 73 74 61 72 74 0d | key to restart.| 000001f0 0a 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa |..............U.| 00000200 =============================== StdErr Messages: =============================== umount: /isodevice: device is busy. (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1))

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• Why (not) logic programming?

  - by Anto

  I have not yet heard about any uses of a logical programming language (such as Prolog) in the software industry, nor do I know of usage of it in hobby programming or open source projects. It (Prolog) is used as an academic language to some extent, though (why is it used in academia?). This makes me wonder, why should you use logic programming, and why not? Why is it not getting any detectable industry usage?

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• Open Source developers: Need your help to answer an 8-minute academic survey

  - by Yi Wang

  I am a research in University of California, Irvine (UCI). I am conducting a research on collaboration tool usage in Open Source development. Your answers will help us to develop new, powerful tools in future. The link of this survey is: http://edu.surveygizmo.com/s3/1035227/Attitude-and-Usage-of-Collaboration-Tools-in-Open-Source-Software-Development The survey only takes you 5-8 mins. thanks a lot for you help!

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• 10 tape technology features that make you go hmm.

  - by Karoly Vegh

  A week ago an Oracle/StorageTek Tape Specialist, Christian Vanden Balck, visited Vienna, and agreed to visit customers to do techtalks and update them about the technology boom going around tape. I had the privilege to attend some of his sessions and noted the information and features that took the customers by surprise and made them think. Allow me to share the top 10: I. StorageTek as a brand: StorageTek is one of he strongest names in the Tape field. The brand itself was valued so much by customers that even after Sun Microsystems acquiring StorageTek and the Oracle acquiring Sun the brand lives on with all the Oracle tapelibraries are officially branded StorageTek.See http://www.oracle.com/us/products/servers-storage/storage/tape-storage/overview/index.html II. Disk information density limitations: Disk technology struggles with information density. You haven't seen the disk sizes exploding lately, have you? That's partly because there are physical limits on a disk platter. The size is given, the number of platters is limited, they just can't grow, and are running out of physical area to write to. Now, in a T10000C tape cartridge we have over 1000m long tape. There you go, you have got your physical space and don't need to stuff all that data crammed together. You can write in a reliable pattern, and have space to grow too. III. Oracle has a market share of 62% worldwide in recording head manufacturing. That's right. If you are running LTO drives, with a good chance you rely on StorageTek production. That's two out of three LTO recording heads produced worldwide.  IV. You can store 1 Exabyte data in a single tape library. Yes, an Exabyte. That is 1000 Petabytes. Or, a million Terabytes. A thousand million GigaBytes. You can store that in a stacked StorageTek SL8500 tapelibrary. In one SL8500 you can put 10.000 T10000C cartridges, that store 10TB data (compressed). You can stack 10 of these SL8500s together. Boom. 1000.000 TB.(n.b.: stacking means interconnecting the libraries. Yes, cartridges are moved between the stacked libraries automatically.)  V. EMC: 'Tape doesn't suck after all. We moved on.': Do you remember the infamous 'Tape sucks, move on' Datadomain slogan? Of course they had to put it that way, having only had disk products. But here's a fun fact: on the EMCWorld 2012 there was a major presence of a Tape-tech company - EMC, in a sudden burst of sanity is embracing tape again. VI. The miraculous T10000C: Oracle StorageTek has developed an enterprise-grade tapedrive and cartridge, the T10000C. With awesome numbers: The Cartridge: Native 5TB capacity, 10TB with compression Over a kilometer long tape within the cartridge. And it's locked when unmounted, no rattling of your data.  Replaced the metalparticles datalayer with BaFe (bariumferrite) - metalparticles lose around 7% of magnetism within 30 days. BaFe does not. Yes we employ solid-state physicists doing R&D on demagnetisation in our labs. Can be partitioned, storage tiering within the cartridge!  The Drive: 2GB Cache Encryption implemented in HW - no performance hit 252 MB/s native sustained data rate, beats disk technology by far. Not to mention peak throughput.  Leading the tape while never touching the data side of it, protecting your data physically too Data integritiy checking (CRC recalculation) on tape within the drive without having to read it back to the server reordering data from tape-order, delivering it back in application-order  writing 32 tracks at once, reading them back for CRC check at once VII. You only use 20% of your data on a regular basis. The rest 80% is just lying around for years. On continuously spinning disks. Doubly consuming energy (power+cooling), blocking diskstorage capacity. There is a solution called SAM (Storage Archive Manager) that provides you a filesystem unifying disk and tape, moving data on-demand and for clients transparently between the different storage tiers. You can share these filesystems with NFS or CIFS for clients, and enjoy the low TCO of tape. Tapes don't spin. They sit quietly in their slots, storing 10TB data, using no energy, producing no heat, automounted when a client accesses their data.See: http://www.oracle.com/us/products/servers-storage/storage/storage-software/storage-archive-manager/overview/index.html VIII. HW supported for three decades: Did you know that the original PowderHorn library was released in '87 and has been only discontinued in 2010? That is over two decades of supported operation. Tape libraries are - just like the data carrying on tapecartridges - built for longevity. Oh, and the T10000C cartridge has 30-year archival life for long-term retention.  IX. Tape is easy to manage: Have you heard of Tape Storage Analytics? It is a central graphical tool to summarize, monitor, analyze dataflow, health and performance of drives and libraries, see: http://www.oracle.com/us/products/servers-storage/storage/tape-storage/tape-analytics/overview/index.html X. The next generation: The T10000B drives were able to reuse the T10000A cartridges and write on them even more data. On the same cartridges. We call this investment protection, and this is very important for Oracle for the future too. We usually support two generations of cartridges together. The current drive is a T10000C. (...I know I promised to enlist 10, but I got still two more I really want to mention. Allow me to work around the problem: ) X++. The TallBots, the robots moving around the cartridges in the StorageTek library from tapeslots to the drives are cableless. Cables, belts, chains running to moving parts in a library cause maintenance downtimes. So StorageTek eliminated them. The TallBots get power, commands, even firmwareupgrades through the rails they are running on. Also, the TallBots don't just hook'n'pull the tapes out of their slots, they actually grip'n'lift them out. No friction, no scratches, no zillion little plastic particles floating around in the library, in the drives, on your data. (X++)++: Tape beats SSDs and Disks. In terms of throughput (252 MB/s), in terms of TCO: disks cause around 290x more power and cooling, in terms of capacity: 10TB on a single media and soon more.  So... do you need to store large amounts of data? Are you legally bound to archive it for dozens of years? Would you benefit from automatic storage tiering? Have you got large mediachunks to be streamed at times? Have you got power and cooling issues in the growing datacenters? Do you find EMC's 180° turn of tape attitude interesting, but appreciate it at the same time? With all that, you aren't alone. The most data on this planet is stored on tape. Tape is coming. Big time.

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• Real tortoises keep it slow and steady. How about the backups?

  - by Maria Zakourdaev

    … Four tortoises were playing in the backyard when they decided they needed hibiscus flower snacks. They pooled their money and sent the smallest tortoise out to fetch the snacks. Two days passed and there was no sign of the tortoise. "You know, she is taking a lot of time", said one of the tortoises. A little voice from just out side the fence said, "If you are going to talk that way about me I won't go." Is it too much to request from the quite expensive 3rd party backup tool to be a way faster than the SQL server native backup? Or at least save a respectable amount of storage by producing a really smaller backup files?  By saying “really smaller”, I mean at least getting a file in half size. After Googling the internet in an attempt to understand what other “sql people” are using for database backups, I see that most people are using one of three tools which are the main players in SQL backup area:  LiteSpeed by Quest SQL Backup by Red Gate SQL Safe by Idera The feedbacks about those tools are truly emotional and happy. However, while reading the forums and blogs I have wondered, is it possible that many are accustomed to using the above tools since SQL 2000 and 2005.  This can easily be understood due to the fact that a 300GB database backup for instance, using regular a SQL 2005 backup statement would have run for about 3 hours and have produced ~150GB file (depending on the content, of course).  Then you take a 3rd party tool which performs the same backup in 30 minutes resulting in a 30GB file leaving you speechless, you run to management persuading them to buy it due to the fact that it is definitely worth the price. In addition to the increased speed and disk space savings you would also get backup file encryption and virtual restore -  features that are still missing from the SQL server. But in case you, as well as me, don’t need these additional features and only want a tool that performs a full backup MUCH faster AND produces a far smaller backup file (like the gain you observed back in SQL 2005 days) you will be quite disappointed. SQL Server backup compression feature has totally changed the market picture. Medium size database. Take a look at the table below, check out how my SQL server 2008 R2 compares to other tools when backing up a 300GB database. It appears that when talking about the backup speed, SQL 2008 R2 compresses and performs backup in similar overall times as all three other tools. 3rd party tools maximum compression level takes twice longer. Backup file gain is not that impressive, except the highest compression levels but the price that you pay is very high cpu load and much longer time. Only SQL Safe by Idera was quite fast with it’s maximum compression level but most of the run time have used 95% cpu on the server. Note that I have used two types of destination storage, SATA 11 disks and FC 53 disks and, obviously, on faster storage have got my backup ready in half time. Looking at the above results, should we spend money, bother with another layer of complexity and software middle-man for the medium sized databases? I’m definitely not going to do so.  Very large database As a next phase of this benchmark, I have moved to a 6 terabyte database which was actually my main backup target. Note, how multiple files usage enables the SQL Server backup operation to use parallel I/O and remarkably increases it’s speed, especially when the backup device is heavily striped. SQL Server supports a maximum of 64 backup devices for a single backup operation but the most speed is gained when using one file per CPU, in the case above 8 files for a 2 Quad CPU server. The impact of additional files is minimal.  However, SQLsafe doesn’t show any speed improvement between 4 files and 8 files. Of course, with such huge databases every half percent of the compression transforms into the noticeable numbers. Saving almost 470GB of space may turn the backup tool into quite valuable purchase. Still, the backup speed and high CPU are the variables that should be taken into the consideration. As for us, the backup speed is more critical than the storage and we cannot allow a production server to sustain 95% cpu for such a long time. Bottomline, 3rd party backup tool developers, we are waiting for some breakthrough release. There are a few unanswered questions, like the restore speed comparison between different tools and the impact of multiple backup files on restore operation. Stay tuned for the next benchmarks.    Benchmark server: SQL Server 2008 R2 sp1 2 Quad CPU Database location: NetApp FC 15K Aggregate 53 discs Backup statements: No matter how good that UI is, we need to run the backup tasks from inside of SQL Server Agent to make sure they are covered by our monitoring systems. I have used extended stored procedures (command line execution also is an option, I haven’t noticed any impact on the backup performance). SQL backup LiteSpeed SQL Backup SQL safe backup database <DBNAME> to disk= '\\<networkpath>\par1.bak' , disk= '\\<networkpath>\par2.bak', disk= '\\<networkpath>\par3.bak' with format, compression EXECUTE master.dbo.xp_backup_database @database = N'<DBName>', @backupname= N'<DBName> full backup', @desc = N'Test', @compressionlevel=8, @filename= N'\\<networkpath>\par1.bak', @filename= N'\\<networkpath>\par2.bak', @filename= N'\\<networkpath>\par3.bak', @init = 1 EXECUTE master.dbo.sqlbackup '-SQL "BACKUP DATABASE <DBNAME> TO DISK= ''\\<networkpath>\par1.sqb'', DISK= ''\\<networkpath>\par2.sqb'', DISK= ''\\<networkpath>\par3.sqb'' WITH DISKRETRYINTERVAL = 30, DISKRETRYCOUNT = 10, COMPRESSION = 4, INIT"' EXECUTE master.dbo.xp_ss_backup @database = 'UCMSDB', @filename = '\\<networkpath>\par1.bak', @backuptype = 'Full', @compressionlevel = 4, @backupfile = '\\<networkpath>\par2.bak', @backupfile = '\\<networkpath>\par3.bak' If you still insist on using 3rd party tools for the backups in your production environment with maximum compression level, you will definitely need to consider limiting cpu usage which will increase the backup operation time even more: RedGate : use THREADPRIORITY option ( values 0 – 6 ) LiteSpeed : use  @throttle ( percentage, like 70%) SQL safe :  the only thing I have found was @Threads option.   Yours, Maria

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• Firefox Slow down and 100% CPU after gnome-settings-deamon update

  - by digitaljail

  I'm on Ubuntu 12.04 (Unity) with Firefox 17.0.1 instaled. after the latest update of the gnome-settings-deamon (3.4.2-0ubuntu0.5,3.4.2-0ubuntu0.6) FireFox starts taking 100% of my CPU, periodically. I have tried various things: 1) Disabled All the non standard extensions = No change to the CPU Usage 2) Disabled Flash PlugIns (also updated same time) = No change to CPU Usage 3) Disabled "Global Menu integration 3.6.4) Extension = HOOOA CPU OK !!! Any suggestion to get back global menu integration with no more CPU problems?

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