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  • Bad Blocks Exist in Virtual Device PERC H700 Integrated

    - by neoX
    I have a DELL server with PERC H700 Integrated controller. I've made RAID5 with 12 harddrives and the virtual device is in Optimal state, but I receive such errors under linux: sd 0:2:0:0: [sda] Unhandled error code sd 0:2:0:0: [sda] Result: hostbyte=0x07 driverbyte=0x00 sd 0:2:0:0: [sda] CDB: cdb[0]=0x88: 88 00 00 00 00 07 22 50 bd 98 00 00 00 08 00 00 end_request: I/O error, dev sda, sector 30640487832 sd 0:2:0:0: [sda] Unhandled error code sd 0:2:0:0: [sda] Result: hostbyte=0x07 driverbyte=0x00 sd 0:2:0:0: [sda] CDB: cdb[0]=0x88: 88 00 00 00 00 07 22 50 bd 98 00 00 00 08 00 00 end_request: I/O error, dev sda, sector 30640487832 sd 0:2:0:0: [sda] Unhandled error code sd 0:2:0:0: [sda] Result: hostbyte=0x07 driverbyte=0x00 sd 0:2:0:0: [sda] CDB: cdb[0]=0x88: 88 00 00 00 00 07 22 50 bc e0 00 00 01 00 00 00 end_request: I/O error, dev sda, sector 30640487648 But all disk are in Firmware state: Online, Spun Up. Also there is not a single ATA read or write error in any disk in the raid (I check them with smartctl -a -d sat+megaraid,N -H /dev/sda). The only strange thing is in the output in megacli: megacli -LDInfo -L0 -a0 ... Bad Blocks Exist: Yes How could there be bad blocks in a Virtual Drive, which is in optimal state and no disk is broken or even with a single error? I tried "Consistency Check", but it finished successfully and the errors are still in dmesg. Could Someone help me to figure it out what is wrong with my raid?

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  • Dell PERC 5 - RAID-10 keeps rebuilding drive 2 every day

    - by raid question
    I have a Dell PowerEdge 2950 with this card: RAID bus controller [0104]: Dell PowerEdge Expandable RAID controller 5 [1028:0015] and six disks in a RAID-10. I replaced drive 2, because it didn't show up, and then it started to rebuild itself: root@backup01:~# megaraidsas-status -- Arrays informations -- -- ID | Type | Size | Status a0d0 | RAID 10 | 5587GiB | DEGRADED -- Disks informations -- ID | Model | Status | Warnings a0e8s0 | ATA ST2000DM001-9YN1 1863GiB | online | errs: media:0 other:5393 a0e8s1 | ATA ST2000DM001-9YN1 1863GiB | online | errs: media:0 other:5394 a0e8s2 | ATA ST2000DM001-1E61 1863GiB | rebuild | errs: media:0 other:99 a0e8s3 | ATA ST2000DM001-9YN1 1863GiB | online | errs: media:0 other:5393 a0e8s4 | ATA ST2000DM001-9YN1 1863GiB | online | errs: media:0 other:5393 a0e8s5 | ATA ST2000DM001-9YN1 1863GiB | online | errs: media:0 other:5393 The rebuild finishes, then the virtual drive becomes optimal, and drive 2 goes online. Then once a day, drive 2 acts like it's been removed, and the rebuild starts all over again. How do I make this once a day rebuild stop? Event Description: Removed: PD 02(e1/s2) Event Description: Removed: PD 02(e1/s2) Info: enclPd=08, scsiType=0, portMap=04, sasAddr=1221000002000000,0000000000000000 Event Description: State change on VD 00/0 from OPTIMAL(3) to DEGRADED(2) Event Description: VD 00/0 is now DEGRADED1 Event Description: State change on PD 02(e1/s2) from ONLINE(18) to FAILED(11) Event Description: State change on PD 02(e1/s2) from FAILED(11) to UNCONFIGURED_BAD(1) Event Description: Background Initialization failed on VD 00/0 Event Description: Inserted: PD 02(e1/s2) Event Description: Inserted: PD 02(e1/s2) Info: enclPd=08, scsiType=0, portMap=04, sasAddr=1221000002000000,0000000000000000 Event Description: PD 02(e1/s2) is not a certified drive Event Description: State change on PD 02(e1/s2) Event Description: State change on PD 02(e1/s2) from UNCONFIGURED_GOOD(0) to OFFLINE(10) from UNCONFIGURED_BAD(1) to UNCONFIGURED_GOOD(0) Event Description: Rebuild automatically started on PD 02(e1/s2) Event Description: State change on PD 02(e1/s2) from OFFLINE(10) to REBUILD(14)

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  • BIOS setting: AHCI or RAID (when using SSD + 2x HDD in RAID-0)

    - by nixdagibts
    Hello there, I want to add a new SSD and use it as system drive with Win7 x64 installed. As driver I chose newest Intel Rapid Storage driver (not MSAHCI). I know that I have to use AHCI as BIOS setting for optimal SSD read/write performance. But I'm also using 2 normal HDDs as separate RAID-0 SSD: Win7 HDD: RAID-0 HDD: RAID-0 If I set my BIOS on my ASUS P5W DH Deluxe to AHCI, my RAID-0 cant be recognized And If im using RAID as setting, maybe my SSD has not its top speed. But I'm not sure about that. In short: AHCI no RAID-0 RAID no optimal SSD performance (?) Now my question: Can I use RAID as BIOS setting and be sure, that theres no decrease in SSD performance? Google finds so many articles with similar topics and my head is just exploding. Two examples: - set AHCI and after installing OS switch to RAID as BIOS setting... what? - use a diskette and F6 while installing win7... really? O.o I thought those times are gone

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  • Cannot load from raid with grub

    - by Andrew Answer
    I have a RAID1 array on my Ubuntu 12.04 LTS and my /sda HDD has been replaced several days ago. I use this commands to replace: # go to superuser sudo bash # see RAID state mdadm -Q -D /dev/md0 # State should be "clean, degraded" # remove broken disk from RAID mdadm /dev/md0 --fail /dev/sda1 mdadm /dev/md0 --remove /dev/sda1 # see partitions fdisk -l # shutdown computer shutdown now # physically replace old disk by new # start system again # see partitions fdisk -l # copy partitions from sdb to sda sfdisk -d /dev/sdb | sfdisk /dev/sda # recreate id for sda sfdisk --change-id /dev/sda 1 fd # add sda1 to RAID mdadm /dev/md0 --add /dev/sda1 # see RAID state mdadm -Q -D /dev/md0 # State should be "clean, degraded, recovering" # to see status you can use cat /proc/mdstat After bebuilding completion "fdisk -l" says what I have not valid partition table /dev/md0. So 1) "update-grub" find only /sda and /sdb Linux, not /md0 2) "dpkg-reconfigure grub-pc" says "GRUB failed to install the following devices /dev/md0" I cannot load my system except from /sdb1 and /sda1, but in DEGRADED mode... This is my partial fdisk -l output: Disk /dev/sdb: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000667ca Device Boot Start End Blocks Id System /dev/sdb1 * 63 940910984 470455461 fd Linux raid autodetect /dev/sdb2 940910985 976768064 17928540 5 Extended /dev/sdb5 940911048 976768064 17928508+ 82 Linux swap / Solaris Disk /dev/md0: 481.7 GB, 481746288640 bytes 2 heads, 4 sectors/track, 117613840 cylinders, total 940910720 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: 0x00000000 Disk /dev/md0 doesn't contain a valid partition table Anybody can resolve this issue? I have big headache with this.

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  • How to play 24 fps video smoothly on a 60Hz display?

    - by netvope
    I use mpc-hc to play videos on Win7 x64. With the default settings (#1), video playback is great most of the time. But for panning shots, playback is not smooth. I stepped through the video frame by frame and found that the panning movement is smooth (e.g. each frame shifts horizontally by 10 pixels), so the problem is how the 23.976 fps video is interpolated to 60Hz. The judder looks like what would be caused by a "2:3 pulldown", where the frames are played unevenly like: frame 1, 1, 2, 2, 2, 3, 3, 4, 4, 4, etc (#2) Using "optimal renderer settings" (#3) instead of the default disables the Aero theme and causes tearing. Setting my LCD display to 50Hz may have improved the judder slightly (but I can't really tell). My display does not support 24Hz or 48Hz, and forcing them in the Nvidia control panel gives blurry screen. I've tried other video players (VLC and KMPlayer), the ReClock Directshow Filter, video files from different sources (#4), turning on/off DXVA, and a computer with a different GPU, but the judder in the playback is similar. None of them solved the problem. So, how can I play 23.976 or 24 fps video smoothly on a 60Hz display? I think a video player could make the video smoother by doing linear interpolation, such as: 1. 100% frame 1 2. 60% frame 1 + 40% frame 2 3. 20% frame 1 + 80% frame 2 4. 80% frame 2 + 20% frame 3 5. 40% frame 2 + 60% frame 3 6. 100% frame 3 7. 60% frame 3 + 40% frame 4 .. etc Can any existing video player do this? Footnotes: (#1) Video renderer: EVR Custom Pres. (#2) This example converts a 24 fps video into 30 fps (#3) View Renderer settings Reset Reset to optimal renderer settings (#4) The files I have are all H.264 mkv files, but I don't think the file format/encoding matters.

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  • Should I use "Raid 5 + spare" or "Raid 6"?

    - by Trevor Boyd Smith
    What is "Raid 5 + Spare" (excerpt from User Manual, Sect 4.17.2, P.54): RAID5+Spare: RAID 5+Spare is a RAID 5 array in which one disk is used as spare to rebuild the system as soon as a disk fails (Fig. 79). At least four disks are required. If one physical disk fails, the data remains available because it is read from the parity blocks. Data from a failed disk is rebuilt onto the hot spare disk. When a failed disk is replaced, the replacement becomes the new hot spare. No data is lost in the case of a single disk failure, but if a second disk fails before the system can rebuild data to the hot spare, all data in the array will be lost. What is "Raid 6" (excerpt from User Manual, Sect 4.17.2, P.54): RAID6: In RAID 6, data is striped across all disks (minimum of four) and a two parity blocks for each data block (p and q in Fig. 80) is written on the same stripe. If one physical disk fails, the data from the failed disk can be rebuilt onto a replacement disk. This Raid mode can support up to two disk failures with no data loss. RAID 6 provides for faster rebuilding of data from a failed disk. Both "Raid 5 + spare" and "Raid 6" are SO similar ... I can't tell the difference. When would "Raid 5 + Spare" be optimal? And when would "Raid 6" be optimal"? The manual dumbs down the different raid with 5 star ratings. "Raid 5 + Spare" only gets 4 stars but "Raid 6" gets 5 stars. If I were to blindly trust the manual I would conclude that "Raid 6" is always better. Is "Raid 6" always better?

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  • How to play 24 fps video smoothly on a 60Hz display? (or which player supports frame interpolation?)

    - by netvope
    I use mpc-hc to play videos on Win7 x64. With the default settings (#1), video playback is great most of the time. But for panning shots, playback is not smooth. I stepped through the video frame by frame and found that the panning movement is smooth (e.g. each frame shifts horizontally by 10 pixels), so the problem is how the 23.976 fps video is interpolated to 60Hz. The judder looks like what would be caused by a "2:3 pulldown", where the frames are played unevenly like: frame 1, 1, 2, 2, 2, 3, 3, 4, 4, 4, etc (#2) Using "optimal renderer settings" (#3) instead of the default disables the Aero theme and causes tearing. Setting my LCD display to 50Hz may have improved the judder slightly (but I can't really tell). My display does not support 24Hz or 48Hz, and forcing them in the Nvidia control panel gives blurry screen. I've tried other video players (VLC and KMPlayer), the ReClock Directshow Filter, video files from different sources (#4), turning on/off DXVA, and a computer with a different GPU, but the judder in the playback is similar. None of them solved the problem. So, how can I play 23.976 or 24 fps video smoothly on a 60Hz display? I think a video player could make the video smoother by doing linear interpolation, such as: 1. 100% frame 1 2. 60% frame 1 + 40% frame 2 3. 20% frame 1 + 80% frame 2 4. 80% frame 2 + 20% frame 3 5. 40% frame 2 + 60% frame 3 6. 100% frame 3 7. 60% frame 3 + 40% frame 4 .. etc Can any existing video player do this? Footnotes: (#1) Video renderer: EVR Custom Pres. (#2) This example converts a 24 fps video into 30 fps (#3) View Renderer settings Reset Reset to optimal renderer settings (#4) The files I have are all H.264 mkv files, but I don't think the file format/encoding matters.

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  • why does the partition start on sector 2048 instead of 63

    - by gcb
    I had two drives partitioned the same and running 2 raid partitions on each. One died and I replaced it under warranty for the same model. While trying to partition it, the first partition can only start on sector 2048, instead of 63 that was before. Driver have different geometry as previous and remaining ones. (Fewer heads/more cylinders) old drive: $ sudo fdisk -c -u -l /dev/sdb Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 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: 0x000aa189 Device Boot Start End Blocks Id System /dev/sdb1 * 63 174080339 87040138+ 83 Linux /dev/sdb2 174080340 182482334 4200997+ 82 Linux swap / Solaris /dev/sdb3 182482335 3907024064 1862270865 fd Linux raid autodetect remanufactured drive received from warranty: $ sudo fdisk -c -u -l /dev/sda Disk /dev/sda: 2000.4 GB, 2000398934016 bytes 81 heads, 63 sectors/track, 765633 cylinders, total 3907029168 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: 0x000d0b5d Device Boot Start End Blocks Id System /dev/sda1 2048 ... why is that?

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  • Boot records messed on dual boot (win7 and ubuntu) machine with SSD and HDD

    - by Michael
    i have a lenovo ideapad y570 with two hard drives: SSD and normal HDD both managed by RapidDrive and windows 7 pre-installed. First, i have shrunk my 500 GB HDD a little bit to make some place for a linux installation. Then i installed linux mint 12 to it, also installed grub onto the drive (dev/sdb). Installation programm has not allowed me to install grub on sda. Then i replaced linux mint with ubuntu 12.04 but installed grub onto the SSD (which is dev/sda and was the default-option). After that i could boot into my windows, only ubuntu worked. So i did a research, and tried: rewriting mbr of windows into sda1, reinstalling grub, replacing grub2 with grub-legacy, and now i think my partitions table are totally messed. Here is fdisk -l output: ubuntu@ubuntu:~$ sudo fdisk -l Disk /dev/sda: 64.0 GB, 64023257088 bytes 255 heads, 63 sectors/track, 7783 cylinders, total 125045424 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: 0x00000000 Device Boot Start End Blocks Id System /dev/sda1 * 2048 411647 204800 7 HPFS/NTFS/exFAT /dev/sda2 411648 1009430959 504509656 7 HPFS/NTFS/exFAT Disk /dev/sdb: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x5e5d1cc8 Device Boot Start End Blocks Id System /dev/sdb1 * 1979 884389887 442193954+ 12 Compaq diagnostics /dev/sdb2 884391934 976771071 46189569 5 Extended /dev/sdb5 884391936 937705471 26656768 83 Linux /dev/sdb6 937707520 967006207 14649344 83 Linux /dev/sdb7 967008256 976771071 4881408 82 Linux swap / Solaris I also cant mount any windows partitions to recover data. And when i open gparted, the whole sda-disk appears unallocated and it states "can not have a partition outside the disk!", also the end-sector address of /dev/sda2 confuses me. If i boot from the SSD, it throws some mbr error and wont boot, if i boot from the HDD, i only get the grub bash. How do i restore the partition tables? I can boot only from a live-cd at the machine. Thanks for any help.

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  • How to optimize a postgreSQL server for a "write once, read many"-type infrastructure ?

    - by mhu
    Greetings, I am working on a piece of software that logs entries (and related tagging) in a PostgreSQL database for storage and retrieval. We never update any data once it has been inserted; we might remove it when the entry gets too old, but this is done at most once a day. Stored entries can be retrieved by users. The insertion of new entries can happen rather fast and regularly, thus the database will commonly hold several millions elements. The tables used are pretty simple : one table for ids, raw content and insertion date; and one table storing tags and their values associated to an id. User search mostly concern tags values, so SELECTs usually consist of JOIN queries on ids on the two tables. To sum it up : 2 tables Lots of INSERT no UPDATE some DELETE, once a day at most some user-generated SELECT with JOIN huge data set What would an optimal server configuration (software and hardware, I assume for example that RAID10 could help) be for my PostgreSQL server, given these requirements ? By optimal, I mean one that allows SELECT queries taking a reasonably little amount of time. I can provide more information about the current setup (like tables, indexes ...) if needed.

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  • Shrinking windows and recovery partitions on the samsung new series 9

    - by bobbaluba
    I just bought a samsung NP900X3C, and as I was going to install linux, I noticed the windows partitions and recovery partitions occupied a major portion of the disk. The disk is a 128 GB SSD, and I want to keep the windows partition in order to play some games once in a while, but the windows disk is already 45GB full (with no installed programs) and the recovery partition is 20GB. That leaves under 60 GB for linux, which is not optimal, since that is what I'm going to be using most of the time, and there would be no room for games on the windows partition. There are also two small partitions that I don't know what are doing, one 100mb at the start of the disk that I'm guessing is some kind of boot partition, and one 5GB, that is described as an OS/2 hidden C: drive What I'm wondering is: can i delete the recovery partition? What about the mystical 5gb partition? Here is what fdisk reports: ubuntu@ubuntu:~$ sudo fdisk -l Disk /dev/sda: 128.0 GB, 128035676160 bytes 255 heads, 63 sectors/track, 15566 cylinders, total 250069680 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: 0x83953ffc Device Boot Start End Blocks Id System /dev/sda1 * 2048 206847 102400 7 HPFS/NTFS/exFAT /dev/sda2 206848 198273023 99033088 7 HPFS/NTFS/exFAT /dev/sda3 198273024 207276031 4501504 84 OS/2 hidden C: drive /dev/sda4 207276032 250068991 21396480 27 Hidden NTFS WinRE

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  • Various problems with software raid1 array built with Samsung 840 Pro SSDs

    - by Andy B
    I am bringing to ServerFault a problem that is tormenting me for 6+ months. I have a CentOS 6 (64bit) server with an md software raid-1 array with 2 x Samsung 840 Pro SSDs (512GB). Problems: Serious write speed problems: root [~]# time dd if=arch.tar.gz of=test4 bs=2M oflag=sync 146+1 records in 146+1 records out 307191761 bytes (307 MB) copied, 23.6788 s, 13.0 MB/s real 0m23.680s user 0m0.000s sys 0m0.932s When doing the above (or any other larger copy) the load spikes to unbelievable values (even over 100) going up from ~ 1. When doing the above I've also noticed very weird iostat results: Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.00 1589.50 0.00 54.00 0.00 13148.00 243.48 0.60 11.17 0.46 2.50 sdb 0.00 1627.50 0.00 16.50 0.00 9524.00 577.21 144.25 1439.33 60.61 100.00 md1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 md2 0.00 0.00 0.00 1602.00 0.00 12816.00 8.00 0.00 0.00 0.00 0.00 md0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 And it keeps it this way until it actually writes the file to the device (out from swap/cache/memory). The problem is that the second SSD in the array has svctm and await roughly 100 times larger than the second. For some reason the wear is different between the 2 members of the array root [~]# smartctl --attributes /dev/sda | grep -i wear 177 Wear_Leveling_Count 0x0013 094% 094 000 Pre-fail Always - 180 root [~]# smartctl --attributes /dev/sdb | grep -i wear 177 Wear_Leveling_Count 0x0013 070% 070 000 Pre-fail Always - 1005 The first SSD has a wear of 6% while the second SSD has a wear of 30%!! It's like the second SSD in the array works at least 5 times as hard as the first one as proven by the first iteration of iostat (the averages since reboot): Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 10.44 51.06 790.39 125.41 8803.98 1633.11 11.40 0.33 0.37 0.06 5.64 sdb 9.53 58.35 322.37 118.11 4835.59 1633.11 14.69 0.33 0.76 0.29 12.97 md1 0.00 0.00 1.88 1.33 15.07 10.68 8.00 0.00 0.00 0.00 0.00 md2 0.00 0.00 1109.02 173.12 10881.59 1620.39 9.75 0.00 0.00 0.00 0.00 md0 0.00 0.00 0.41 0.01 3.10 0.02 7.42 0.00 0.00 0.00 0.00 What I've tried: I've updated the firmware to DXM05B0Q (following reports of dramatic improvements for 840Ps after this update). I have looked for "hard resetting link" in dmesg to check for cable/backplane issues but nothing. I have checked the alignment and I believe they are aligned correctly (1MB boundary, listing below) I have checked /proc/mdstat and the array is Optimal (second listing below). root [~]# fdisk -ul /dev/sda Disk /dev/sda: 512.1 GB, 512110190592 bytes 255 heads, 63 sectors/track, 62260 cylinders, total 1000215216 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: 0x00026d59 Device Boot Start End Blocks Id System /dev/sda1 2048 4196351 2097152 fd Linux raid autodetect Partition 1 does not end on cylinder boundary. /dev/sda2 * 4196352 4605951 204800 fd Linux raid autodetect Partition 2 does not end on cylinder boundary. /dev/sda3 4605952 814106623 404750336 fd Linux raid autodetect root [~]# fdisk -ul /dev/sdb Disk /dev/sdb: 512.1 GB, 512110190592 bytes 255 heads, 63 sectors/track, 62260 cylinders, total 1000215216 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: 0x0003dede Device Boot Start End Blocks Id System /dev/sdb1 2048 4196351 2097152 fd Linux raid autodetect Partition 1 does not end on cylinder boundary. /dev/sdb2 * 4196352 4605951 204800 fd Linux raid autodetect Partition 2 does not end on cylinder boundary. /dev/sdb3 4605952 814106623 404750336 fd Linux raid autodetect /proc/mdstat root # cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdb2[1] sda2[0] 204736 blocks super 1.0 [2/2] [UU] md2 : active raid1 sdb3[1] sda3[0] 404750144 blocks super 1.0 [2/2] [UU] md1 : active raid1 sdb1[1] sda1[0] 2096064 blocks super 1.1 [2/2] [UU] unused devices: Running a read test with hdparm root [~]# hdparm -t /dev/sda /dev/sda: Timing buffered disk reads: 664 MB in 3.00 seconds = 221.33 MB/sec root [~]# hdparm -t /dev/sdb /dev/sdb: Timing buffered disk reads: 288 MB in 3.01 seconds = 95.77 MB/sec But look what happens if I add --direct root [~]# hdparm --direct -t /dev/sda /dev/sda: Timing O_DIRECT disk reads: 788 MB in 3.01 seconds = 262.08 MB/sec root [~]# hdparm --direct -t /dev/sdb /dev/sdb: Timing O_DIRECT disk reads: 534 MB in 3.02 seconds = 176.90 MB/sec Both tests increase but /dev/sdb doubles while /dev/sda increases maybe 20%. I just don't know what to make of this. As suggested by Mr. Wagner I've done another read test with dd this time and it confirms the hdparm test: root [/home2]# dd if=/dev/sda of=/dev/null bs=1G count=10 10+0 records in 10+0 records out 10737418240 bytes (11 GB) copied, 38.0855 s, 282 MB/s root [/home2]# dd if=/dev/sdb of=/dev/null bs=1G count=10 10+0 records in 10+0 records out 10737418240 bytes (11 GB) copied, 115.24 s, 93.2 MB/s So sda is 3 times faster than sdb. Or maybe sdb is doing also something else besides what sda does. Is there some way to find out if sdb is doing more than what sda does? UPDATE Again, as suggested by Mr. Wagner, I have swapped the 2 SSDs. And as he thought it would happen, the problem moved from sdb to sda. So I guess I'll RMA one of the SSDs. I wonder if the cage might be problematic. What is wrong with this array? Please help!

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  • dual boot install--no GRUB

    - by Jim Syyap
    My computer recently had a hardware upgrade and now runs on Windows 7. I decided to install Ubuntu 11.04 as dual boot using the ISO I got from ubuntu.com downloaded onto my USB stick. Restarting with the USB stick, I was able to install Ubuntu 11.04 choosing the option: Install Ubuntu 11.04 side by side with Windows 7 (or something like that). No errors were encountered on installation. However on restarting, there was no GRUB; the system went straight into Windows 7. Looking for answers, I found these: http://essayboard.com/2011/07/12/how-to-dual-boot-ubuntu-11-04-and-windows-7-the-traditional-way-through-grub-2/ http://ubuntuforums.org/showthread.php?t=1774523 Following their instructions, I got: Boot Info Script 0.60 from 17 May 2011 ============================= Boot Info Summary: =============================== => Windows is installed in the MBR of /dev/sda. => Syslinux MBR (3.61-4.03) is installed in the MBR of /dev/sdb. => Grub2 (v1.99) is installed in the MBR of /dev/sdc and looks at sector 1 of the same hard drive for core.img. core.img is at this location and looks for (,msdos7)/boot/grub on this drive. sda1: __________________________________________________ ________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files: /grldr /bootmgr /Boot/BCD /grldr sda2: __________________________________________________ ________________________ 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: /Windows/System32/winload.exe sdb1: __________________________________________________ ________________________ File system: vfat Boot sector type: SYSLINUX 4.02 debian-20101016 ...........>...r>....... ......0...~.k...~...f...M.f.f....f..8~....>2} Boot sector info: Syslinux looks at sector 1437504 of /dev/sdb1 for its second stage. SYSLINUX is installed in the directory. The integrity check of the ADV area failed. According to the info in the boot sector, sdb1 starts at sector 0. But according to the info from fdisk, sdb1 starts at sector 62. Operating System: Boot files: /boot/grub/grub.cfg /syslinux/syslinux.cfg /ldlinux.sys sdc1: __________________________________________________ ________________________ File system: ntfs Boot sector type: Windows XP Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files: sdc2: __________________________________________________ ________________________ File system: Extended Partition Boot sector type: - Boot sector info: sdc5: __________________________________________________ ________________________ File system: swap Boot sector type: - Boot sector info: sdc6: __________________________________________________ ________________________ File system: swap Boot sector type: - Boot sector info: sdc7: __________________________________________________ ________________________ File system: ext4 Boot sector type: - Boot sector info: Operating System: Ubuntu 11.04 Boot files: /boot/grub/grub.cfg /etc/fstab /boot/grub/core.img sdc8: __________________________________________________ ________________________ File system: swap Boot sector type: - Boot sector info: Going back into Ubuntu and running sudo fdisk -l , I got these: ubuntu@ubuntu:~$ sudo fdisk -l 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: 0x0002f393 Device Boot Start End Blocks Id System /dev/sda1 * 1 13 102400 7 HPFS/NTFS Partition 1 does not end on cylinder boundary. /dev/sda2 13 19458 156185600 7 HPFS/NTFS Disk /dev/sdb: 2011 MB, 2011168768 bytes 62 heads, 62 sectors/track, 1021 cylinders Units = cylinders of 3844 * 512 = 1968128 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000f2ab9 Device Boot Start End Blocks Id System /dev/sdb1 * 1 1021 1962331 c W95 FAT32 (LBA) Disk /dev/sdc: 1000.2 GB, 1000202043392 bytes 255 heads, 63 sectors/track, 121600 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: 0x00261ddd Device Boot Start End Blocks Id System /dev/sdc1 * 1 60657 487222656+ 7 HPFS/NTFS /dev/sdc2 60657 121600 489527681 5 Extended /dev/sdc5 120563 121600 8337703+ 82 Linux swap / Solaris /dev/sdc6 120073 120562 3930112 82 Linux swap / Solaris /dev/sdc7 60657 119584 473328640 83 Linux /dev/sdc8 119584 120072 3923968 82 Linux swap / Solaris Should I proceed and do the following? Assuming Ubuntu 11.04 was installed on device sdb1, do this: sudo mount /dev/sdb1 /mnt Then do this: sudo grub-install--root-directory=/mnt /dev/sdb Notice there are two dashes in front of the root directory, and I'm not using sdb1 but sdb. Since the command in step 15 had reinstalled Grub 2, now we need to unmount the /mnt (i.e. sdb1) to clean up. Do this: sudo umount /mnt Reboot and remove Ubuntu 11.04 CD/DVD from disk tray. Log into Ubuntu 11.04 (you have no choice but it will make you log into Ubuntu 11.04 at this point). Open up a terminal in Ubuntu 11.04 (using real installation, not live CD/DVD). Execute this command: sudo update-grub Reboot the machine.

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  • Oracle Fusion Middleware (OFM) 11g (11.1.1.7) Starter Kit available & Customizable Demos

    - by JuergenKress
    OFM PS6 starter kit is now available from Global Sales Engineering (GSE, formerly DSS).  OFM Starter Kit provides a basic foundation to design and develop middleware demos. It is based on plug and play architecture and designed to use optimal hardware resources.  The starter kit is easily extendable to incorporate more Oracle Fusion Middleware components. New Features Built on the "Build your own demos (POC)" concept Starter Kit comes with core OFM Components Oracle Unified Directory (OUD, SOA, WebCenter Content and WebCenter Spaces) Starter Kit is available over the Internet and is tuned for optimal performance Portable/Downloadable version of the Starter Kit will be available soon. Please check Demos Corner. For and questions/feedback please contact chandan Das or Anand Prasad. Call to Action Review the Release Notes. & Visit the GSE Website and book the “OFM 11.1.1.7.0 Base Platform” customizable instance. Further information about this platform is available on this page. This announcement will appear in the archive as number 412. Customizable Demos We are happy to announce the availability of the SOA 11.1.1.7.0 Platform.  SOA 11g (11.1.1.7) Platform is fully featured, built on Plug and Play architecture, and designed to develop best of breed SOA demos. New Features Built on the "Build your own demos" concept Fusion Middleware products SOA, BAM, OSB, OEP, OER, OSR, WebCenter Content and WebCenter Spaces are installed, configured, and tuned for better performance Demo instances are available over the Internet Portable version of the platform will be available soon. Please check Demos Corner For questions/feedback please contact Anvesh Baluguri or Anand Prasad. Call to Action Review the Release Notes & Visit the GSE Website and book the “SOA 11.1.1.7.0 Platform” customizable demo. Further information about this platform is available on this page.  This announcement will appear in the archive as number 413. To get access to the demo environment please contact OPN! Support If you need assistance or encounter any issues please submit a GSE Repository ticket or call the GSE Support Hotline for assistance. The GSE Support Hotline is available 24 hours a day, Monday through Friday, at: US/CAN: +1.650.506.8763 & EMEA: +44 118 9240808 & APAC: +65.6436.2150 & LAD: +1.650.506.8763 & Japan: +81-3-6834-6097. SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Mix Forum Technorati Tags: OFM,demos,sales,marketing,dss,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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  • Automount of external hard disk

    - by moose
    I have an Intenso 6002560 1TB Memory Station - an external hard disk. This hard disk gets connected via Y-USB cable. When I connect both USB-ends to my Notebook, it gets recognized by my Ubuntu 10.04.4 LTS system: moose@pc07:~$ lsusb [...] Bus 002 Device 005: ID 13fd:1840 Initio Corporation [...] and Disk /dev/sda: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00065e10 Device Boot Start End Blocks Id System /dev/sda1 * 1 37810 303704064 83 Linux /dev/sda2 37810 38914 8864769 5 Extended /dev/sda5 37810 38914 8864768 82 Linux swap / Solaris Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0d6ea32a Device Boot Start End Blocks Id System /dev/sdc1 1 121601 976759008+ c W95 FAT32 (LBA) But it did not get mounted: moose@pc07:/dev$ mount -l /dev/sda1 on / type ext4 (rw,errors=remount-ro,user_xattr) proc on /proc type proc (rw,noexec,nosuid,nodev) none on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) none on /dev type devtmpfs (rw,mode=0755) none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) none on /dev/shm type tmpfs (rw,nosuid,nodev) none on /var/run type tmpfs (rw,nosuid,mode=0755) none on /var/lock type tmpfs (rw,noexec,nosuid,nodev) none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755) binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev) gvfs-fuse-daemon on /home/moose/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=moose) However, I could mount it manually with mount -t vfat /dev/sdc1 /mnt/sdc1 as you can see here: moose@pc07:~$ mount -l /dev/sda1 on / type ext4 (rw,errors=remount-ro,user_xattr) proc on /proc type proc (rw,noexec,nosuid,nodev) none on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) none on /dev type devtmpfs (rw,mode=0755) none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) none on /dev/shm type tmpfs (rw,nosuid,nodev) none on /var/run type tmpfs (rw,nosuid,mode=0755) none on /var/lock type tmpfs (rw,noexec,nosuid,nodev) none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755) binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev) gvfs-fuse-daemon on /home/moose/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=moose) /dev/sdc1 on /mnt/sdc1 type vfat (rw) edit: Another command: moose@pc07:~$ sudo blkid -o list device fs_type label mount point UUID ---------------------------------------------------------------------------------------------------------------------- /dev/sda1 ext4 / 45eb611b-517e-425b-8057-0391726cccd5 /dev/sda5 swap <swap> e9dc42f3-594c-4b62-874a-305eda5eed41 moose@pc07:~$ blkid -o list device fs_type label mount point UUID ---------------------------------------------------------------------------------------------------------------------- /dev/sda1 ext4 / 45eb611b-517e-425b-8057-0391726cccd5 /dev/sda5 swap <swap> e9dc42f3-594c-4b62-874a-305eda5eed41 /dev/sdc1 /mnt/sdc1 edit: another command: moose@pc07:~$ ls -l /dev/disk/by-uuid/ total 0 lrwxrwxrwx 1 root root 10 2012-09-30 09:31 45eb611b-517e-425b-8057-0391726cccd5 -> ../../sda1 lrwxrwxrwx 1 root root 10 2012-09-30 09:31 e9dc42f3-594c-4b62-874a-305eda5eed41 -> ../../sda5 Here is a link to a Launchpad question about this problem. But I would like it to mount automatically. What do I have to do?

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  • Grub Rescue Unknown Filesystem Error. Grub Corrupted or Filesystem?

    - by nightcrawler
    Now it has happened twice & have been pulling my hairs now... I have installed xubuntu on my external hardisk & have been using it for about 3 months. It has three partitions, one of 500 mb mounted at /boot, 2nd one of 48gb mounted at / & the rest (out of 160gb) is ntfs partition....used as normal external storage. The last storage supposedly acts as a buffer b/w Linux distributions & Win platform, buffer in the sense that it provides a universal channel for data transfers. I have constantly used this external hardisk for data transfers b/w win7 laptop & xubuntu (on this external hd) without any hassle. However, on of my desktops where I have ubuntu I (for the first time) attached this external drive which let me do data transfers where all three partitions properly mounted....but then nasty thing occurred the same that occurred before. I (as usual) tried booting via this external hd (one having xubuntu, one having being formerly used under Ubuntu) I got error Now I am totally devastated because similar thing happened ~6months before when I had fedora 17 in my external hd (instead of xubuntu) & after it was used under ubuntu the same happened...i didn't reported it because I already had planned towards debian instead of rpm! The mystery is that as long as I don't attach this external hd under ubuntu the data never** corrupts whereas under win xp/7 I can use it as a normal usb storage of coarse linux partitions aren’t available under win platforms... **From corrupts I mean hd fails to boot with the error mentioned however cant say whether data within remains untouched? It seems that my grub & or MBR is corrupted. Please sir guide me to solve this issue also why I cant attach & use linux external hds under linux platform Disk /dev/sdc: 160.0 GB, 160041884672 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581806 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: 0x0004e7d0 Device Boot Start End Blocks Id System /dev/sdc1 * 2048 976895 487424 83 Linux /dev/sdc2 978942 96874495 47947777 5 Extended /dev/sdc3 96874496 312575999 107850752 7 HPFS/NTFS/exFAT /dev/sdc5 978944 94726143 46873600 83 Linux /dev/sdc6 94728192 96874495 1073152 82 Linux swap / Solaris I can recall for sure that have seen a thread here when a similar problem occurred & in response someone gave solution of how to mount (now invisible) partitions & recover important data in them. I have misplaced that URL so if any can guide me thither because my important documents resides in / partition What I already have done: Without success I have tried this & related solutions What I plan to do: I believe that filesystem has corrupted & would you recommend solution like this provided I cant recall whether my /boot (500mb) partition was ext4 or ext2 though I am sure that my / (48gb) partition was ext4 UPDATE 1 Attached my external hd under Ubuntu ran followinf command as root grub-install /dev/sdc where /dev/sdc was my external hd containing corrupted xubuntu....it reported all done! I re-ran fdisk -l but to my disappointment it reported Disk /dev/sdc: 160.0 GB, 160041884672 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581806 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: 0x1b6b9167 Disk /dev/sdc doesn't contain a valid partition table ...& now I can't even access its ntfs partition (former /dev/sdc3) please help? UPDATE 2 TestDisk (by cgsecurity) failed at founding any partition table :( TestDisk 6.13, Data Recovery Utility, November 2011 Christophe GRENIER <[email protected]> http://www.cgsecurity.org Disk /dev/sdc - 160 GB / 149 GiB - CHS 19457 255 63 Partition Start End Size in sectors

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  • Stale statistics on a newly created temporary table in a stored procedure can lead to poor performance

    - by sqlworkshops
    When you create a temporary table you expect a new table with no past history (statistics based on past existence), this is not true if you have less than 6 updates to the temporary table. This might lead to poor performance of queries which are sensitive to the content of temporary tables.I was optimizing SQL Server Performance at one of my customers who provides search functionality on their website. They use stored procedure with temporary table for the search. The performance of the search depended on who searched what in the past, option (recompile) by itself had no effect. Sometimes a simple search led to timeout because of non-optimal plan usage due to this behavior. This is not a plan caching issue rather temporary table statistics caching issue, which was part of the temporary object caching feature that was introduced in SQL Server 2005 and is also present in SQL Server 2008 and SQL Server 2012. In this customer case we implemented a workaround to avoid this issue (see below for example for workarounds).When temporary tables are cached, the statistics are not newly created rather cached from the past and updated based on automatic update statistics threshold. Caching temporary tables/objects is good for performance, but caching stale statistics from the past is not optimal.We can work around this issue by disabling temporary table caching by explicitly executing a DDL statement on the temporary table. One possibility is to execute an alter table statement, but this can lead to duplicate constraint name error on concurrent stored procedure execution. The other way to work around this is to create an index.I think there might be many customers in such a situation without knowing that stale statistics are being cached along with temporary table leading to poor performance.Ideal solution is to have more aggressive statistics update when the temporary table has less number of rows when temporary table caching is used. I will open a connect item to report this issue.Meanwhile you can mitigate the issue by creating an index on the temporary table. You can monitor active temporary tables using Windows Server Performance Monitor counter: SQL Server: General Statistics->Active Temp Tables. The script to understand the issue and the workaround is listed below:set nocount onset statistics time offset statistics io offdrop table tab7gocreate table tab7 (c1 int primary key clustered, c2 int, c3 char(200))gocreate index test on tab7(c2, c1, c3)gobegin trandeclare @i intset @i = 1while @i <= 50000begininsert into tab7 values (@i, 1, ‘a’)set @i = @i + 1endcommit trangoinsert into tab7 values (50001, 1, ‘a’)gocheckpointgodrop proc test_slowgocreate proc test_slow @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_slow 1godbcc dropcleanbuffersgo–high reads that are not expected for parameter ’2'exec test_slow 2godrop proc test_with_recompilegocreate proc test_with_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_with_recompile 1godbcc dropcleanbuffersgo–high reads that are not expected for parameter ’2'–low reads on 3rd execution as expected for parameter ’2'exec test_with_recompile 2godrop proc test_with_alter_table_recompilegocreate proc test_with_alter_table_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)–to avoid caching of temporary tables one can create a constraint–but this might lead to duplicate constraint name error on concurrent usagealter table #temp1 add constraint test123 unique(c1)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_with_alter_table_recompile 1godbcc dropcleanbuffersgo–low reads as expected for parameter ’2'exec test_with_alter_table_recompile 2godrop proc test_with_index_recompilegocreate proc test_with_index_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)–to avoid caching of temporary tables one can create an indexcreate index test on #temp1(c1)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgoset statistics time onset statistics io ondbcc dropcleanbuffersgo–high reads as expected for parameter ’1'exec test_with_index_recompile 1godbcc dropcleanbuffersgo–low reads as expected for parameter ’2'exec test_with_index_recompile 2go

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  • Observing flow control idle time in TCP

    - by user12820842
    Previously I described how to observe congestion control strategies during transmission, and here I talked about TCP's sliding window approach for handling flow control on the receive side. A neat trick would now be to put the pieces together and ask the following question - how often is TCP transmission blocked by congestion control (send-side flow control) versus a zero-sized send window (which is the receiver saying it cannot process any more data)? So in effect we are asking whether the size of the receive window of the peer or the congestion control strategy may be sub-optimal. The result of such a problem would be that we have TCP data that we could be transmitting but we are not, potentially effecting throughput. So flow control is in effect: when the congestion window is less than or equal to the amount of bytes outstanding on the connection. We can derive this from args[3]-tcps_snxt - args[3]-tcps_suna, i.e. the difference between the next sequence number to send and the lowest unacknowledged sequence number; and when the window in the TCP segment received is advertised as 0 We time from these events until we send new data (i.e. args[4]-tcp_seq = snxt value when window closes. Here's the script: #!/usr/sbin/dtrace -s #pragma D option quiet tcp:::send / (args[3]-tcps_snxt - args[3]-tcps_suna) = args[3]-tcps_cwnd / { cwndclosed[args[1]-cs_cid] = timestamp; cwndsnxt[args[1]-cs_cid] = args[3]-tcps_snxt; @numclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } tcp:::send / cwndclosed[args[1]-cs_cid] && args[4]-tcp_seq = cwndsnxt[args[1]-cs_cid] / { @meantimeclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = avg(timestamp - cwndclosed[args[1]-cs_cid]); @stddevtimeclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = stddev(timestamp - cwndclosed[args[1]-cs_cid]); @numclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = count(); cwndclosed[args[1]-cs_cid] = 0; cwndsnxt[args[1]-cs_cid] = 0; } tcp:::receive / args[4]-tcp_window == 0 && (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { swndclosed[args[1]-cs_cid] = timestamp; swndsnxt[args[1]-cs_cid] = args[3]-tcps_snxt; @numclosed["swnd", args[2]-ip_saddr, args[4]-tcp_dport] = count(); } tcp:::send / swndclosed[args[1]-cs_cid] && args[4]-tcp_seq = swndsnxt[args[1]-cs_cid] / { @meantimeclosed["swnd", args[2]-ip_daddr, args[4]-tcp_sport] = avg(timestamp - swndclosed[args[1]-cs_cid]); @stddevtimeclosed["swnd", args[2]-ip_daddr, args[4]-tcp_sport] = stddev(timestamp - swndclosed[args[1]-cs_cid]); swndclosed[args[1]-cs_cid] = 0; swndsnxt[args[1]-cs_cid] = 0; } END { printf("%-6s %-20s %-8s %-25s %-8s %-8s\n", "Window", "Remote host", "Port", "TCP Avg WndClosed(ns)", "StdDev", "Num"); printa("%-6s %-20s %-8d %@-25d %@-8d %@-8d\n", @meantimeclosed, @stddevtimeclosed, @numclosed); } So this script will show us whether the peer's receive window size is preventing flow ("swnd" events) or whether congestion control is limiting flow ("cwnd" events). As an example I traced on a server with a large file transfer in progress via a webserver and with an active ssh connection running "find / -depth -print". Here is the output: ^C Window Remote host Port TCP Avg WndClosed(ns) StdDev Num cwnd 10.175.96.92 80 86064329 77311705 125 cwnd 10.175.96.92 22 122068522 151039669 81 So we see in this case, the congestion window closes 125 times for port 80 connections and 81 times for ssh. The average time the window is closed is 0.086sec for port 80 and 0.12sec for port 22. So if you wish to change congestion control algorithm in Oracle Solaris 11, a useful step may be to see if congestion really is an issue on your network. Scripts like the one posted above can help assess this, but it's worth reiterating that if congestion control is occuring, that's not necessarily a problem that needs fixing. Recall that congestion control is about controlling flow to prevent large-scale drops, so looking at congestion events in isolation doesn't tell us the whole story. For example, are we seeing more congestion events with one control algorithm, but more drops/retransmission with another? As always, it's best to start with measures of throughput and latency before arriving at a specific hypothesis such as "my congestion control algorithm is sub-optimal".

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  • Need help partitioning when reinstalling Ubuntu 14.04

    - by Chris M.
    I upgraded to 14.04 about a month ago on my HP Mini netbook (about 16 GB hard disk). A few days ago the system crashed (I don't know why but I was using internet at the time). When I restarted the computer, Ubuntu would not load. Instead, I got a message from the BIOS saying Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key I took this to mean that I needed to reinstall 14.04. When I try to reinstall Ubuntu from the USB stick, I choose "Erase disk and install Ubuntu" but then I get a message: Some of the partitions you created are too small. Please make the following partitions at least this large: / 3.3 GB If you do not go back to the partitioner and increase the size of these partitions, the installation may fail. At first I hit Continue to see if it would install anyway, and it gave the message: The attempt to mount a file system with type ext4 in SCSI1 (0,0,0), partition # 1 (sda) at / failed. You may resume partitioning from the partitioning menu. The second time I hit Go Back, and it took me to the following partitioning table: Device Type Mount Point Format Size Used System /dev/sda /dev/sda1 ext4 (checked) 3228 MB Unknown /dev/sda5 swap (not checked) 1063 MB Unknown + - Change New Partition Table... Revert Device for boot loader installation: /dev/sda ATA JM Loader 001 (4.3 GB) At this point I'm not sure what to do. I've never partitioned my hard drive before and I don't want to screw things up. (I'm not particularly tech savvy.) Can you instruct me what I should do. (P.S. I'm afraid the table might not appear as I typed it in.) Results from fdisk: ubuntu@ubuntu:~$ sudo fdisk -l Disk /dev/sda: 4294 MB, 4294967296 bytes 255 heads, 63 sectors/track, 522 cylinders, total 8388608 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: 0x00000000 Disk /dev/sda doesn't contain a valid partition table Disk /dev/sdb: 7860 MB, 7860125696 bytes 155 heads, 31 sectors/track, 3194 cylinders, total 15351808 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: 0x0009a565 Device Boot Start End Blocks Id System /dev/sdb1 * 2768 15351807 7674520 b W95 FAT32 ubuntu@ubuntu:~$ Here is what it displays when I open the Disks utility (I tried the screenshot terminal command you suggested but it didn't seem to do anything): 4.3 GB Hard Disk /dev/sda Model: JM Loader 001 (01000001) Size: 4.3 GB (4,294,967,296 bytes) Serial Number: 01234123412341234 Assessment: SMART is not supported Volumes Size: 4.3 GB (4,294,967,296 bytes) Device: /dev/sda Contents: Unknown (There is a button in the utility that when you click it gives the following options: Format... Create Disk Image... Restore Disk Image... Benchmark but SMART Data & Self-Tests... is dimmed out) When I hit F9 Change Boot Device Order, it shows the hard drive as: SATA:PM-JM Loader 001 When I hit F10 to get me into the BIOS Setup Utility, under Diagnostic it shows: Primary Hard Disk Self Test Not Support NetworkManager Tool State: disconnected Device: eth0 Type: Wired Driver: atl1c State: unavailable Default: no HW Address: 00:26:55:B0:7F:0C Capabilities: Carrier Detect: yes Wired Properties Carrier: off When I run command lshw -C network, I get: WARNING: you should run this program as super-user. *-network description: Network controller product: BCM4312 802.11b/g LP-PHY vendor: Broadcom Corporation physical id: 0 bus info: pci@0000:01:00.0 version: 01 width: 64 bits clock: 33MHz capabilities: bus_master cap_list configuration: driver=b43-pci-bridge latency=0 resources: irq:16 memory:feafc000-feafffff *-network description: Ethernet interface product: AR8132 Fast Ethernet vendor: Qualcomm Atheros physical id: 0 bus info: pci@0000:02:00.0 logical name: eth0 version: c0 serial: 00:26:55:b0:7f:0c capacity: 100Mbit/s width: 64 bits clock: 33MHz capabilities: bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=atl1c driverversion=1.0.1.1-NAPI latency=0 link=no multicast=yes port=twisted pair resources: irq:43 memory:febc0000-febfffff ioport:ec80(size=128) WARNING: output may be incomplete or inaccurate, you should run this program as super-user.

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  • Grub2 : Windows 7 can't boot installing with Ubuntu 10.04 on different hard drive

    - by dellphi
    I use a dual boot with two hard disks and two OS is Ubuntu 10.04 and Windows 7. Windows 7 installed on the first disk, first partition. Grub is installed on a second hard disk MBR, and Ubuntu installed on an extended partition on a second hard drive. When I select Windows 7 on the Grub menu, the HDD lamp lights up briefly and then black screen on the monitor, with the status of the keyboard is still functioning. Until now (with the default boot from first HDD), I have to press F12 to get into the Grub to run Linux on a second HDD. ================ fdisk -l ================================ dellph1@dellph1-desktop:~$ fdisk -l omitting empty partition (5) Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00087dec Device Boot Start End Blocks Id System /dev/sda1 * 1 23104 185582848+ 7 HPFS/NTFS /dev/sda2 23105 121601 791177122 5 Extended /dev/sda5 36107 74408 307660783+ 7 HPFS/NTFS /dev/sda6 74409 100081 206218341 7 HPFS/NTFS /dev/sda7 100082 121601 172859368+ 7 HPFS/NTFS Disk /dev/sdb: 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: 0x6d43dfb2 Device Boot Start End Blocks Id System /dev/sdb1 1 10030 80560066 5 Extended /dev/sdb5 * 1 5560 44657601 83 Linux /dev/sdb6 5560 9387 30736384 83 Linux /dev/sdb7 9387 10030 5164032 82 Linux swap / Solaris dellph1@dellph1-desktop:~$ ================= grub.cfg ================== # DO NOT EDIT THIS FILE # It is automatically generated by /usr/sbin/grub-mkconfig using templates from /etc/grub.d and settings from /etc/default/grub # BEGIN /etc/grub.d/00_header if [ -s $prefix/grubenv ]; then load_env fi set default="0" if [ ${prev_saved_entry} ]; then set saved_entry=${prev_saved_entry} save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z ${boot_once} ]; then saved_entry=${chosen} save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n ${have_grubenv} ]; then if [ -z ${boot_once} ]; then save_env recordfail; fi; fi } insmod ext2 set root='(hd1,5)' search --no-floppy --fs-uuid --set 2f014a3a-35f3-4d05-87aa-34ca677160b7 if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=1024x768 insmod gfxterm insmod vbe if terminal_output gfxterm ; then true ; else # For backward compatibility with versions of terminal.mod that don't # understand terminal_output terminal gfxterm fi fi insmod ext2 set root='(hd1,5)' search --no-floppy --fs-uuid --set 2f014a3a-35f3-4d05-87aa-34ca677160b7 set locale_dir=($root)/boot/grub/locale set lang=en insmod gettext if [ ${recordfail} = 1 ]; then set timeout=-1 else set timeout=5 fi END /etc/grub.d/00_header BEGIN /etc/grub.d/05_debian_theme insmod ext2 set root='(hd1,5)' search --no-floppy --fs-uuid --set 2f014a3a-35f3-4d05-87aa-34ca677160b7 insmod jpeg if background_image /usr/share/backgrounds/CurlsbyCandy.jpg ; then set color_normal=white/black set color_highlight=black/light-gray else set menu_color_normal=white/black set menu_color_highlight=black/light-gray fi END /etc/grub.d/05_debian_theme BEGIN /etc/grub.d/10_linux menuentry 'Ubuntu, with Linux 2.6.32-24-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod ext2 set root='(hd1,5)' search --no-floppy --fs-uuid --set 2f014a3a-35f3-4d05-87aa-34ca677160b7 linux /boot/vmlinuz-2.6.32-24-generic root=UUID=2f014a3a-35f3-4d05-87aa-34ca677160b7 ro splash vga=795 quiet splash nomodeset video=uvesafb:mode_option=1280x1024-24,mtrr=3,scroll=ywrap initrd /boot/initrd.img-2.6.32-24-generic } menuentry 'Ubuntu, with Linux 2.6.32-24-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod ext2 set root='(hd1,5)' search --no-floppy --fs-uuid --set 2f014a3a-35f3-4d05-87aa-34ca677160b7 echo 'Loading Linux 2.6.32-24-generic ...' linux /boot/vmlinuz-2.6.32-24-generic root=UUID=2f014a3a-35f3-4d05-87aa-34ca677160b7 ro single splash vga=795 echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-2.6.32-24-generic } END /etc/grub.d/10_linux BEGIN /etc/grub.d/30_os-prober menuentry "Windows 7 (loader) (on /dev/sda1)" { insmod ntfs set root='(hd0,1)' search --no-floppy --fs-uuid --set 5cac2139ac210f58 chainloader +1 } END /etc/grub.d/30_os-prober BEGIN /etc/grub.d/40_multisystem Ajout de MultiSystem MULTISYSTEM MENU menuentry "PLoP Boot Manager" { linux16 /boot/plpbt } menuentry "Smart Boot Manager" { search --set -f /boot/sbootmgr.dsk linux16 /boot/memdisk initrd16 /boot/sbootmgr.dsk } FIN MULTISYSTEM MENU END /etc/grub.d/40_multisystem ================================================ I want to keep the Grub on the second HDD. I have been using the Startup Manager, Boot Manager and Grub Customizer, and this problem still unsolved. The easiest thing that I can possibly do is to install Grub on first HDD, but I was curious and maybe someone can help.

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  • How to fix: Ubuntu 12.04 reboots after loading with elilo

    - by Casey
    I have an HP p6-2120 with CPU: AMD A6-3620 APU with Radeon Graphics RAM: 6GB BIOS: HO2_710.ROM v7.10 [AMI v7.10 4/19/2012] Disk: SATA1 (/dev/sda) - 1 TB (windows) Disk: SATA2 (/dev/sdb) - 1 TB partitioned using "parted -a optimal /dev/sdb" as follows: .. 1049KB 201MB FAT32 boot flag set .. 201MB 60GB ext2 (/) .. 68GB 78GB linux-swap(v1) (swap) .. 78GB 790GB ext4 (/home) .. - rest is "free" space reserved for other purposes (eventually) ubuntu: 12.04.1 LTS [specifically: Release 12.04 (precise) 64-bit] kernel: linux 3.2.0-29-generic I created a bootable EFI USB from the ISO (64-bit) which I downloaded. I can run and install from the USB without any problems. The BIOS is an EFI bios that appears to be capable of booting in either EFI or Legacy mode. Initially, I did the "standard" install with NOTHING on disk2, and let the installer configure everything. The net result of this was that when I started the computer and forced it into "boot" menu mode, it DOES NOT recognize SATA2 as an EFI drive, and when I attempt to "legacy" boot from it, I get the message "ERROR: No Boot Disk has been detected." The "standard" install created one large partition that consumed the entire disk. At that point, I manually partitioned the disk (using sudo parted -a optimal /dev/sdb) as described above. I selected the "other" install, and changed the /dev/sdb1 to "bios_grub", /dev/sdb2 as "/" (ext4), /dev/sdb3 as swap, and /dev/sdb4 as "/home". [Note: fearing that possibly elilo did not recognize ext4, I switched /dev/sdb2 to ext2 and re-insalled] The net result was that the install appeared to trash the /dev/sdb1 partition so that it was NOT readable by anything. I re-formated /dev/sdb1 as FAT32 and set the boot flag. I repeated the install ignoring the messages about no bios_grub partition. After several attempts to get GRUB2 to work, I switched to elilo. I downloaded the most recent version and copied it (elilo-3.14-ia64.efi) to /dev/sdb1/efi/boot/bootx64.efi. (The BIOS boot loader did not recognize it either as elilo-3.14.ia64.efi or as elilo.efi. Based on the advice in one of the web-pages I found, I renamed it to bootx64.efi. This worked.) In that same directory (/efi/boot), I copied the file pointed to the link in /dev/sdb2/vmlinuz to /efi/boot/vmlinuz, and the file pointed to the link in /dev/sdb2/initrd.img to /efi/boot/initrd.img. I created an elilo.conf file as follows: timeout=5000 prompt default=linux-boot image=vmlinuz label=linux-boot read-only initrd=initrd.img root=/dev/sdb2 The /efi/boot directory contains 4 files: bootx64.efi elilo.conf vmlinuz initrd.img When I power-cycle the computer and force the boot menu, drive2 shows up as an EFI bootable drive. When I select it, I get the elilo prompt. Pressing , it appears to load the kernal (I have tried it with verbose=5, and there is a long string of messages with the final one a command line to load the kernel and a series of several dots that fly by) then the screen goes blank, and it reboots the computer. [Note: I have also tried substituting the UUID as found in the /etc/fstab of the installed system for the root directory. This had no effect.] This is a brief synopsis of several nights of fiddling with this. I would deeply appreciate any help you can give.

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  • installer can't find partition, but fdisk can find them

    - by pxd
    I'm installing ubuntu 12.04, my system had install 2 system -- winxp and ubuntu 10.10. Now, I want to update ubuntu to 12.04. I use usb disk to install 12.04. But, the installer can't not find my partition in my harddisk. But, the fdisk can find them. Can you help me? How to do? ubuntu@ubuntu:~$ sudo lshw -short H/W path Device Class Description system HP 2230s (NN868PA#AB2) /0 bus 3037 /0/9 memory 64KiB BIOS /0/0 processor Intel(R) Core(TM)2 Duo CPU T6570 @ 2.10GHz /0/0/1 memory 2MiB L2 cache /0/0/3 memory 32KiB L1 cache /0/0/0.1 processor Logical CPU /0/0/0.2 processor Logical CPU /0/2 memory 32KiB L1 cache /0/4 memory 2GiB System Memory /0/4/0 memory SODIMM [empty] /0/4/1 memory 2GiB SODIMM DDR2 Synchronous 800 MHz (1.2 ns) /0/100 bridge Mobile 4 Series Chipset Memory Controller Hub /0/100/2 display Mobile 4 Series Chipset Integrated Graphics Controller /0/100/2.1 display Mobile 4 Series Chipset Integrated Graphics Controller /0/100/1a bus 82801I (ICH9 Family) USB UHCI Controller #4 /0/100/1a.1 bus 82801I (ICH9 Family) USB UHCI Controller #5 /0/100/1a.2 bus 82801I (ICH9 Family) USB UHCI Controller #6 /0/100/1a.7 bus 82801I (ICH9 Family) USB2 EHCI Controller #2 /0/100/1b multimedia 82801I (ICH9 Family) HD Audio Controller /0/100/1c bridge 82801I (ICH9 Family) PCI Express Port 1 /0/100/1c.1 bridge 82801I (ICH9 Family) PCI Express Port 2 /0/100/1c.1/0 wlan1 network PRO/Wireless 5100 AGN [Shiloh] Network Connection /0/100/1c.2 bridge 82801I (ICH9 Family) PCI Express Port 3 /0/100/1c.4 bridge 82801I (ICH9 Family) PCI Express Port 5 /0/100/1c.5 bridge 82801I (ICH9 Family) PCI Express Port 6 /0/100/1c.5/0 eth1 network 88E8072 PCI-E Gigabit Ethernet Controller /0/100/1d bus 82801I (ICH9 Family) USB UHCI Controller #1 /0/100/1d.1 bus 82801I (ICH9 Family) USB UHCI Controller #2 /0/100/1d.2 bus 82801I (ICH9 Family) USB UHCI Controller #3 /0/100/1d.7 bus 82801I (ICH9 Family) USB2 EHCI Controller #1 /0/100/1e bridge 82801 Mobile PCI Bridge /0/100/1f bridge ICH9M LPC Interface Controller /0/100/1f.2 scsi0 storage 82801IBM/IEM (ICH9M/ICH9M-E) 4 port SATA Controller [AHCI mode] /0/100/1f.2/0 /dev/sda disk 500GB WDC WD5000BEVT-0 /0/100/1f.2/0/1 /dev/sda1 volume 48GiB Windows NTFS volume /0/100/1f.2/0/2 /dev/sda2 volume 416GiB Extended partition /0/100/1f.2/0/2/5 /dev/sda5 volume 97GiB HPFS/NTFS partition /0/100/1f.2/0/2/6 /dev/sda6 volume 198GiB HPFS/NTFS partition /0/100/1f.2/0/2/7 /dev/sda7 volume 27GiB Linux filesystem partition /0/100/1f.2/0/2/8 /dev/sda8 volume 93GiB Linux filesystem partition /0/100/1f.2/1 /dev/cdrom disk CDDVDW TS-L633M /0/1 scsi6 storage /0/1/0.0.0 /dev/sdb disk 15GB STORAGE DEVICE /0/1/0.0.0/0 /dev/sdb disk 15GB /0/1/0.0.0/0/1 /dev/sdb1 volume 14GiB Windows FAT volume /1 power HZ04037 ubuntu@ubuntu:~$ ubuntu@ubuntu:~$ sudo fdisk -l Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x31263125 Device Boot Start End Blocks Id System /dev/sda1 * 63 102277727 51138832+ 7 HPFS/NTFS/exFAT /dev/sda2 102277728 976784129 437253201 f W95 Ext'd (LBA) /dev/sda5 102277791 307078127 102400168+ 7 HPFS/NTFS/exFAT /dev/sda6 307078191 724141151 208531480+ 7 HPFS/NTFS/exFAT /dev/sda7 724142080 781459455 28658688 83 Linux /dev/sda8 781461504 976771071 97654784 83 Linux Disk /dev/sdb: 15.9 GB, 15931539456 bytes 64 heads, 32 sectors/track, 15193 cylinders, total 31116288 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: 0x0009eb92 Device Boot Start End Blocks Id Systemfile:///home/ubuntu/Pictures/Screenshot%20from%202012-07-07%2010:25:40.png /dev/sdb1 * 32 31115263 15557616 c W95 FAT32 (LBA) ubuntu 12.04 installer can't find the partition in my hard disk, only find device - /dev/sda.(sorry, I'm new user, so can't send image.)

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  • faster implementation of sum ( for Codility test )

    - by Oscar Reyes
    How can the following simple implementation of sum be faster? private long sum( int [] a, int begin, int end ) { if( a == null ) { return 0; } long r = 0; for( int i = begin ; i < end ; i++ ) { r+= a[i]; } return r; } EDIT Background is in order. Reading latest entry on coding horror, I came to this site: http://codility.com which has this interesting programming test. Anyway, I got 60 out of 100 in my submission, and basically ( I think ) is because this implementation of sum, because those parts where I failed are the performance parts. I'm getting TIME_OUT_ERROR's So, I was wondering if an optimization in the algorithm is possible. So, no built in functions or assembly would be allowed. This my be done in C, C++, C#, Java or pretty much in any other. EDIT As usual, mmyers was right. I did profile the code and I saw most of the time was spent on that function, but I didn't understand why. So what I did was to throw away my implementation and start with a new one. This time I've got an optimal solution [ according to San Jacinto O(n) -see comments to MSN below - ] This time I've got 81% on Codility which I think is good enough. The problem is that I didn't take the 30 mins. but around 2 hrs. but I guess that leaves me still as a good programmer, for I could work on the problem until I found an optimal solution: Here's my result. I never understood what is those "combinations of..." nor how to test "extreme_first"

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  • Is there any way to optimize this LINQ where clause that searches for multiple keywords on multiple

    - by Daniel T.
    I have a LINQ query that searches for multiple keywords on multiple columns. The intention is that the user can search for multiple keywords and it will search for the keywords on every property in my Media entity. Here is a simplified example: var result = repository.GetAll<Media>().Where(x => x.Title.Contains("Apples") || x.Description.Contains("Apples") || x.Tags.Contains("Apples") || x.Title.Contains("Oranges") || x.Description.Contains("Oranges") || x.Tags.Contains("Oranges") || x.Title.Contains("Pears") || x.Description.Contains("Pears") || x.Tags.Contains("Pears") ); In other words, I want to search for the keywords Apples, Oranges, and Pears on the columns Title, Description, and Tags. The outputted SQL looks like this: SELECT * FROM Media this_ WHERE (((((((( this_.Title like '%Apples%' or this_.Description like '%Apples%') or this_.Tags like '%Apples%') or this_.Title like '%Oranges%') or this_.Description like '%Oranges%') or this_.Tags like '%Oranges%') or this_.Title like '%Pears%') or this_.Description like '%Pears%') or this_.Tags like '%Pears%') Is this the most optimal SQL in this case? If not, how do I rewrite the LINQ query to create the most optimal SQL statement? I'm using SQLite for testing and SQL Server for actual deployment.

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  • recursively implementing 'minimum number of coins' in python

    - by user5198
    This problem is same as asked in here. Given a list of coins, their values (c1, c2, c3, ... cj, ...), and the total sum i. Find the minimum number of coins the sum of which is i (we can use as many coins of one type as we want), or report that it's not possible to select coins in such a way that they sum up to S. I"m just introduced to dynamic programming yesterday and I tried to make a code for it. # Optimal substructure: C[i] = 1 + min_j(C[i-cj]) cdict = {} def C(i, coins): if i <= 0: return 0 if i in cdict: return cdict[i] else: answer = 1 + min([C(i - cj, coins) for cj in coins]) cdict[i] = answer return answer Here, C[i] is the optimal solution for amount of money 'i'. And available coins are {c1, c2, ... , cj, ...} for the program, I've increased the recursion limit to avoid maximum recursion depth exceeded error. But, this program gives the right answer only someones and when a solution is not possible, it doesn't indicate that. What is wrong with my code and how to correct it?

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