[CentOS] CentOS 6.0 CR mdadm-3.2.2 breaks Intel BIOS RAID

[Steve Brooks]

On Sat, 8 Oct 2011, Trey Dockendorf wrote:

> I just upgraded my home KVM server to CentOS 6.0 CR to make use of the
> latest libvirt and now my RAID array with my VM storage is missing.  It
> seems that the upgrade to mdadm-3.2.2 is the culprit.
>
> This is the output from mdadm when scanning that array,
>
> # mdadm --detail --scan
> ARRAY /dev/md0 metadata=imsm UUID=734f79cf:22200a5a:73be2b52:3388006b
> ARRAY /dev/md126 metadata=imsm UUID=3d135942:f0fad0b0:33255f78:29c3f50a
> mdadm(IMSM): Unsupported attributes : 40000000
> mdadm: IMSM metadata loading not allowed due to attributes incompatibility.
> mdadm(IMSM): Unsupported attributes : 40000000
> mdadm: IMSM metadata loading not allowed due to attributes incompatibility.
> ARRAY /dev/md127 container=/dev/md0 member=0
> UUID=734f79cf:22200a5a:73be2b52:3388006b
>
> The error about IMSM shows up on google as something that happened to Fedora
> users during a FC14->FC15 upgrade.
>
> The server itself isn't old, it's a Supermicro 2U with Dual Xeon 5400 family
> of CPU.  There are two RAIDs on this one controller...a RAID1 which still
> functions and a RAID5 which is the one that is unable to be seen.  I don't
> know what IMSM is for, but the only thing strange about that array is it is
> 2.7TB so the BIOS configured it as two separate arrays, one as 2TB and one
> as 700GB, but it was showing up to CentOS as a single volume.
>
> I downgraded to 3.2.1 , ran mdadm again and bam...it works,
>
> # mdadm --detail --scan
> ARRAY /dev/md0 metadata=imsm UUID=734f79cf:22200a5a:73be2b52:3388006b
> ARRAY /dev/md126 metadata=imsm UUID=3d135942:f0fad0b0:33255f78:29c3f50a
> ARRAY /dev/md127 container=/dev/md0 member=0
> UUID=691f975d:6beecfd8:67b39886:b7ee7f6e
>
> Hopefully this can be fixed before this version makes it to 6.1, though it's
> likely a problem for upstream RHEL as well.
>
> - Trey
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Hmm I recall seeing something like this on an "sl6" box. I think it needed 
a "/etc/mdadm.conf" with som metadata id code.. I am pretty sure I fixed 
it with

mdadm --detail --scan >> /etc/mdadm.conf

and a reboot.

Steve