#4 Patch for RAID6 support

John Brzezniak

Attached is the patch for Raid6 support for EVMS 2.5.3
(sorry, I have not upgraded to 2.5.4 so this patch is
untested on that version and right now I do not have
the time to patch it and test it out).

The patch has been tested for successfull cases.
All raid levels work in creating and deleting the raid
array, as well as clearing volumes and filesystems on
top of it. Resizing/shrinking has not been thourroughly
tested so there may be some problems there. I've been
using EVMS 2.5.3 with Gentoo Linux 2.6.15 for over a
week now and it has been working well. Raid6 requires a
minimum of 4 disks to be created. All other
functionality inherits from the current Raid5
functionality in EVMS.

If you have any questions please let me know at


-- John


  • John Brzezniak
    John Brzezniak

    EVMS 2.5.3 patch for Linux kernel 2.6 RAID6 support

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    Thanks for your contribution! RAID 6 support has been on
    our list of things to do. It's always good to see others
    pitching in to improve EVMS.

    It's good to know that the basic functions work with the
    RAID 6 code in the kernel. That's a big step forward.

    I see two things that need to be done. One is that the
    patch has to be ported to the latest CVS code or at least
    2.5.4. I tried to apply the patch to the latest CVS code
    and it failed.

    The second and more difficult task is to add the kernel RAID
    6 striping logic to the plug-in. The plug-in has to be able
    to read and write to the array whether it is active or not.
    When the array is active in the kernel, the plug-in can
    just pass reads and writes to the array. If the array is
    not active, the plug-in must do the striping itself for the
    reads and writes to the array devices. For an example, see
    the raid5_volume_write() function in plugins/md/raid5_mgr.c.

    RAID 6 support should probably be made into its own plug-in
    rather than be an augment of the RAID 5 plug-in. It should
    be easy enough to break out your changes into a separate
    raid6_mgr.c file.

    I realize you don't have much time to work on this further.
    Hopefully the final work can be done soon to add complete
    RAID 6 support to EVMS.

    Thanks for your initial code and the basic testing.

    Steve D.

  • John Brzezniak
    John Brzezniak

    Logged In: YES
    Originator: YES

    To apply this patch, please run patch as follows:
    patch -l -p0 < evms-2.5.3-raid6.patch