RAID-6 corruption

[Jim Paris]

Hello,

(I've posted some messages about this to linux-raid, but haven't
gotten much of a response; this time I'm cc'ing to linux-kernel)

I am seeing reproducible corruption with software RAID-6 on an array
that has been created with missing disks.  The attached script
demonstrates this easily through loopback devices, but I see the
problem just the same on real drives.

I do not see the problem with full RAID-6 arrays (no missing disks),
nor do I see it on RAID-5 arrays on the same system.  I haven't seen
the corruption when writing directly to the md device, but I haven't
tested that very much.

Tested on 2.6.6, 2.6.7, 2.6.8-rc2, with mdadm 1.5.0 and 1.6.0.
See attached.

-jim

Attachment: r6test.sh
Description: Bourne shell script