Interesting SCSI-Problem with Quantum Atlas10K3

From: Holger Kipp (h.kipp_at_eurowings.com)
Date: 09/28/04

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    Date: Tue, 28 Sep 2004 15:47:07 +0200
To: freebsd-stable@freebsd.org

    Hello,

    maybe someone could help me a bit with this.
    OS is FreeBSD 4.10 , .. , 4.2

    Questions at the end.

    3 SCSI-Harddisks (Quantum ATLAS10K3) as Raid5 (vinum)

    produce the following errors on current hardware
    (ie LSI mtp-controller dual channel U320) - it takes
    a few file operations, though:

    mpt0: bullet missed in timeout
    mpt1: bullet missed in timeout

    (offending disks are located at mpt)

    I/O-Performance is ok, but a simple 'find' that is
    running through all directories will bring the
    system to a near-halt after half a minute or so.

    Copying a 90MB file on the vinum-raid works like a
    charm and does not trigger this behaviour.

    I tried reducing / disabling tagged queueing, but
    that did not help
    Even added an entry in cam_xpt.c with
    /*quirks*/0, /*mintags*/24, /*maxtags*/32
    which seemed to worsen the effect.

    According to the data*** I just found. These disks
    have a queue depth of 64.

    Mounting the drives (or the vinum-drive) read-only
    gives no errors, and rebuilding the array does not
    give an error either.

    So it looks like I need many consecutive read- and write-
    operations to trigger this behaviour (like with find,
    changing access times of directories).

    I have not found any possibility of updating the firmware
    either, so any clue is welcome.

    Disks located at mpt0 do not show any problems, even with
    buildworld.

    I had similar problems with the same disks on older hardware
    (Asus P2B-S) with FreeBSD 4-2, then upgraded to 4.10-STABLE
    and changed all the hardware except for the harddisks.

    - Anyone else who had these problems?
    - How can I find out on what drive the command queue grows
       indefinitely (till the system halts completely), if this
       is at all the case?
    - can I tune FreeBSD in this respect?
    - what are the exact meanings of mintags and maxtags and should
       I try something like /*quirks*/0, /*mintags*/2, /*maxtags*/64 ?
    - ...

    Hints on how to use camdebug are also welcome!

    Best regards,
    Holger Kipp
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