Re: Reproducable OOPS with MD RAID-5 on 2.6.0-test11
From: Kevin P. Fleming
Date: Tue Dec 02 2003 - 08:17:17 EST
Nathan Scott wrote:
One thing that might be of interest - XFS does tend to pass
variable size requests down to the block layer, and this has
tripped up md and other drivers in 2.4 in the distant past.
Log IO is typically 512 byte aligned (as opposed to block or
page size aligned), as are IOs into several of XFS' metadata
structures.
Hey, thanks for the pointer! I think we're getting somewhere now. Here's
a recap of the tested combinations:
XFS on raw disk: OK
XFS on LVM2 on single disk: OK
XFS on LVM2 on RAID-5: fails
ext2 on LVM2 on RAID-5: OK
I just tested XFS on LVM2 on RAID-5 using "-l sunit=8" while creating
the filesystem to force log writes be block-sized and block-aligned;
this seems to work :-) I have not been able to force a failure using my
test script, although ATM the system is still running a RAID-5 resync of
the array, but that should only make the problem more likely, not less.
So, this does appear to be an md/dm stacking problem, that is exposed by
XFS sending non-block-sized and/or non-block-aligned IOs.
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