[Lustre-discuss] md raid6 recommended?

Robin Humble rjh+lustre at cita.utoronto.ca
Thu Nov 15 00:30:26 PST 2007


I notice that raid6 is recommended in the manual. eg. "...RAID6 is a must."
  http://manual.lustre.org/manual/LustreManual16_HTML/DynamicHTML-11-1.html

which I found a bit surprising given that in Dec '06 Peter Braam said
on this list "Some of our customers experienced data corruption in the
RAID6 layer.", and recommending the CFS optimised md raid5 path through
the kernel.

I can't see any patches in lustre 1.6.3 that apply to a raid6 path,
although perhaps none of these raid* patches are applied to a modern
kernel with a raid456 module anyway? 
I could easily be wrong... I haven't diff'd trees pre-and post patching.

anyway, I'm a bit confused. can you guys please clarify the recommended
and/or fast paths through the kernels md layer please?

cheers,
robin




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