Odd Disk activity - Redhat

This is a discussion on Odd Disk activity - Redhat ; Hi, I've been looking at some sar logs on a couple of machines (RH8) and I keep getting some huge peaks - it looks to me like some sort of bug in sar, but I don't know if anyone has ...

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Thread: Odd Disk activity

  1. Odd Disk activity

    Hi,

    I've been looking at some sar logs on a couple of machines (RH8) and I
    keep getting some huge peaks - it looks to me like some sort of bug in
    sar, but I don't know if anyone has seen this before or not.

    I did sar -p -d at intervals of 1 second and caught it happening when
    my await went up to 60M when it is normally about 20. These happen ever
    hour or so (but not exactly on the hour, and not tallying up with any
    cron process.)

    08:31:41 DEV tps rd_sec/s wr_sec/s avgrq-sz avgqu-sz await
    svctm %util
    08:31:42 cciss/c0d0 3.00 0.00 96.00 32.00 0.03
    8.33 8.33 2.50
    08:31:43 cciss/c0d0 7.00 8.00 168.00 25.14 0.07
    10.14 7.86 5.50
    08:31:44 cciss/c0d0 5.00 0.00 168.00 33.60 0.06
    12.80 6.60 3.30
    08:31:45 cciss/c0d0 4.00 0.00 40.00 10.00 0.03
    7.25 5.25 2.10
    08:31:46 cciss/c0d0 9.00 0.00 664.00 73.78 0.21
    23.67 7.89 7.10
    08:31:47 cciss/c0d0 11.00 64.00 96.00 14.55 0.10
    9.09 5.27 5.80
    08:31:48 cciss/c0d0 36.00 16.00 688.00 19.56 1.23
    34.08 5.06 18.20
    08:31:49 cciss/c0d0 10.00 0.00 208.00 20.80 0.24
    24.40 6.00 6.00
    08:31:50 cciss/c0d0 6.00 0.00 168.00 28.00 0.12
    20.50 8.83 5.30
    08:31:51 cciss/c0d0 5.00 0.00 104.00 20.80 0.07
    14.20 7.00 3.50
    08:31:52 cciss/c0d0 4.00 0.00 120.00 30.00 0.05
    11.75 9.25 3.70
    08:31:53 cciss/c0d0 71.00 0.00 912.00 12.85 5.77
    60374428.97 2.59 18.40
    08:31:54 cciss/c0d0 4.00 0.00 80.00 20.00 0.05
    12.25 8.25 3.30
    08:31:55 cciss/c0d0 5.00 0.00 136.00 27.20 0.07
    14.40 7.40 3.70
    08:31:56 cciss/c0d0 8.00 0.00 136.00 17.00 0.19
    23.75 6.38 5.10
    08:31:57 cciss/c0d0 4.00 0.00 40.00 10.00 0.04
    9.25 6.75 2.70
    08:31:58 cciss/c0d0 8.26 0.00 300.92 36.44 0.10
    12.11 8.56 7.06
    08:31:59 cciss/c0d0 132.00 1688.00 160.00 14.00 1.57
    5.23 7.01 92.50

    Ever seen anything like this before? Any ideas of where I should look?

    Thanks,

    Keith


  2. Re: Odd Disk activity

    On Thu, 06 Apr 2006 01:37:08 -0700, keith wrote:

    > Hi,
    >
    > I've been looking at some sar logs on a couple of machines (RH8) and I
    > keep getting some huge peaks - it looks to me like some sort of bug in
    > sar, but I don't know if anyone has seen this before or not.
    >
    > I did sar -p -d at intervals of 1 second and caught it happening when
    > my await went up to 60M when it is normally about 20. These happen ever
    > hour or so (but not exactly on the hour, and not tallying up with any
    > cron process.)
    >


    I'd suggest a 'badblocks' run on the disk. It's easy to do and doesn't
    take forever. When I see unusual disk activity that's where I start.


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