RAID-6 development snapshot (not quite working yet)

RAID-6 development snapshot (not quite working yet)

[H. Peter Anvin]

Hi all,

I've finally been able to shake loose enough time (or more like it, I
needed a project or I'd go insane) to get my RAID-6 project
relaunched.  I now have a development snapshot against linux-2.6.0 and
mdadm-1.4.0 available at:

ftp://ftp.kernel.org/pub/linux/kernel/people/hpa/raid6-20031220-dontuse.tar.gz

This release is "dontuse" because there is some kind of problem with
I/O scheduling in degraded mode (both 1- and 2-degraded mode.)  As a
result, raid6d eventually goes into an infinite loop.

However, the data is definitely there -- I can create a filesystem on
a raid, and it will still fsck clean after gunning two disks.  I
suspect that there is some corner case in the RAID-5 code which I
haven't understood properly and just blindly copied over, which just
doesn't work quite right for RAID-6.

Eyeballs on the code is of course appreciated.  Unfortunately I have
to move house next month, so I'm not sure how much longer I'm going to
be able to have a working test setup :) On the other hand, I think the
code is getting pretty close to actually working :)

Special thanks to Penguin Computing for donating a RAID test system
with enough drives to make meaningful RAID-6 testing possible.

	-hpa



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