XFS and disks with 2K sectors? - SGI

This is a discussion on XFS and disks with 2K sectors? - SGI ; I have some Medea FibreBlock RAID arrays that can operate with either a 512 byte or 2K byte sector size. The arrays consist of five IDE disks and an embedded controller and look like a single disk on the FC ...

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Thread: XFS and disks with 2K sectors?

  1. XFS and disks with 2K sectors?

    I have some Medea FibreBlock RAID arrays that can operate with either a
    512 byte or 2K byte sector size. The arrays consist of five IDE disks
    and an embedded controller and look like a single disk on the FC bus.

    Because inbound 2K requests can be mapped exactly to five 512-byte
    requests to each of the component disks in the RAID set, the arrays are
    somewhat more performant when in 2K sector mode on the FC side. This
    seems to _mostly_ work with Irix; I can use fx to label and partition
    the disks, the resulting label correctly shows a 2K sector size, and I
    can use dd bs=2048 to read and write the disks via the raw partition.

    If I use dd with a 512-byte blocksize, in this mode, it dumps core.

    If I use mkfs_xfs... uh oh. It correctly detects that the sector size
    is 2K, but then at some point attempts to do a write shorter than 2K
    (this is just an inference based on what makes dd dump core) and dumps
    core.

    I'm sure Irix must support SCSI/FC disks with large sector sizes. What's
    going on here?

    The OS is Irix 6.5.17; the FibreBlocks are on a QLA2300 controller and
    work perfectly (albeit not quite as fast as I might like) when set up
    for 512-byte sectors.

    --
    Thor Lancelot Simon tls@rek.tjls.com
    But as he knew no bad language, he had called him all the names of common
    objects that he could think of, and had screamed: "You lamp! You towel! You
    plate!" and so on. --Sigmund Freud

  2. Re: XFS and disks with 2K sectors?

    Thor Lancelot Simon wrote:
    > If I use mkfs_xfs... uh oh. It correctly detects that the sector size
    > is 2K, but then at some point attempts to do a write shorter than 2K
    > (this is just an inference based on what makes dd dump core) and dumps
    > core.
    >
    > I'm sure Irix must support SCSI/FC disks with large sector sizes. What's
    > going on here?


    Unfortunately, XFS on IRIX requires 512byte blocks for metadata
    operations. Of course you can set the filesystem blocksize to 4k for
    data, but writing meta data like the log, AG headers, etc still require
    512byte block writes. Support for larger block sizes has been added to
    Linux and is being added to IRIX, but I couldn't say when or if it will
    be available.

    Ivan
    --
    Ivan Rayner
    ivanr@sgi.com

  3. XFS and disks with 2k sectors?

    Ivan Rayner wrote:

    > Unfortunately, XFS on IRIX requires 512byte blocks for metadata
    > operations. Of course you can set the filesystem blocksize to 4k for
    > data, but writing meta data like the log, AG headers, etc still require
    > 512byte block writes. Support for larger block sizes has been added to
    > Linux and is being added to IRIX, but I couldn't say when or if it will
    > be available.


    I must assume that this still isn't available for Irix 6.5.22 ?

    -Jan

    --
    Jan Schaumann

    Of course it runs NetBSD! http://www.netbsd.org

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