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  1. #1
    Join Date
    Aug 2005
    Posts
    53

    Poor performance of SuperMicro PDSMi and CentOS

    I've got some hardware based on SuperMicro PDSMi and trying to run CentOS 4.4 on it.

    It all installs fine however Disk Performance is extremely poor:

    hdparm -t /dev/hda

    /dev/hda:
    Timing buffered disk reads: 12 MB in 3.30 seconds = 3.64 MB/sec

    hdparm shows the hard drive is running in funny mode:

    /dev/hda:
    multcount = 16 (on)
    IO_support = 0 (default 16-bit)
    unmaskirq = 0 (off)
    using_dma = 0 (off)
    keepsettings = 0 (off)
    readonly = 0 (off)
    readahead = 256 (on)
    geometry = 20023/255/63, sectors = 164696555520, start = 0


    And strange thing DMA can't be enabled:

    hdparm -d1 /dev/hda

    /dev/hda:
    setting using_dma to 1 (on)
    HDIO_SET_DMA failed: Operation not permitted
    using_dma = 0 (off)

    Anyone had a problem like this ?

  2. #2
    Join Date
    Jun 2003
    Location
    UK
    Posts
    6,601
    Not a stupid question but is this a SATA disk or an IDE disk? I had something very similar on a non-supermicro box where SATA was running in "Legacy IDE Mode"
    Russ Foster - Industry Curmudgeon

  3. #3
    Join Date
    Aug 2005
    Posts
    53
    a2b2,

    I guess your guess is right. It is SATA disk but it is detected as ATA disk (looking at dmesg) for some reason

    So how did you fix it ?

  4. #4
    Join Date
    Aug 2006
    Location
    Ashburn VA, San Diego CA
    Posts
    4,571
    Change the SATA mode in the Bios. However, if you installed CentOS with the Bios in the wrong SATA Mode, you may have to reinstall if you don't know how to tweak the boot configuration.
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  5. #5
    Join Date
    May 2001
    Location
    Mass.
    Posts
    56

    Thumbs up

    Thanks for making this thread PeterZaitsev! I realized our PDSMi+ servers suffer the same problem.

    The original test I ran gave results very similar to yours:

    hdparm -t /dev/hda
    /dev/hda:
    Timing buffered disk reads: 10 MB in 3.02 seconds = 3.31 MB/sec

    I then went into the BIOS and changed the Legacy Mode stuff to the following settings:

    PATA : Enabled
    ->Serial .... : Enabled
    ->->SATA ...: Enhanced
    ->->->SATA Raid: Disabled
    ->->->SATA AHCI: Disabled


    After a reboot, the harddrives are now /dev/sda and /dev/sdb and the reads are MUCH faster:

    hdparm -t /dev/sda
    /dev/sda:
    Timing buffered disk reads: 214 MB in 3.03 seconds = 70.73 MB/sec

    DMA would still not turn on BTW:

    hdparm -d1 /dev/sda
    /dev/sda:
    setting using_dma to 1 (on)
    HDIO_SET_DMA failed: Inappropriate ioctl for device

    These servers are running CentOS 4.4 with an (enterprise) OpenVZ kernel, I am not sure if the stock kernel will work, but I will test it if someone is interested.

  6. #6
    Join Date
    Aug 2005
    Posts
    53
    Stock kernels work just fine. That is quite a bummer to make so horrible BIOS defaults.

  7. #7
    Join Date
    May 2001
    Location
    Mass.
    Posts
    56
    Good to know. Yeah I agree.

  8. #8
    Join Date
    Aug 2006
    Location
    Ashburn VA, San Diego CA
    Posts
    4,571
    <edit>

    Nevermind, I don't know what I'm talking about ;-)

    </edit>
    Fast Serv Networks, LLC | AS29889 | Fully Managed Cloud, Streaming, Dedicated Servers, Colo by-the-U
    Since 2003 - Ashburn VA + San Diego CA Datacenters

  9. #9
    Join Date
    Jul 2002
    Location
    London, United Kingdom
    Posts
    4,362
    Quote Originally Posted by PeterZaitsev
    That is quite a bummer to make so horrible BIOS defaults.
    Its not the default :p

    We had exactly the same problem with a couple of pdsmi machines underperforming , one had been set to legacy ide when the raid1 was reconfigured. the other turned out to have a faulty disk.
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