[Beowulf] Big storage

Leif Nixon nixon at nsc.liu.se
Thu Aug 30 13:04:19 EDT 2007


Bruce Allen <ballen at gravity.phys.uwm.edu> writes:

>> I think you should add a parity verification to this - not just a
>> sector scan.
>
> Good idea.  In other words, don't just check that all disk surfaces
> are readable by the disk device.  Also check that the data is
> consistent from the RAID perspective.  Did I understand you correctly?

Exactly. A colleague (hi, Peter!) just found that our shiny (and
cheap) new p400 controllers don't have this rather basic
functionality. So we will probably change our procurement procedures
to avoid this in the future.

And even among those controllers that *can* verify the parity, there
seem to be many that don't handle a detected inconsistency in any sane
fashion. Often they just recompute the parity block and claim that the
damage is "repaired". Yeah, right.

-- 
Leif Nixon                       -            Systems expert
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National Supercomputer Centre    -      Linkoping University
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