2012-01-09 6:25, Richard Elling wrote:
Note: more analysis of the GPFS implementations is needed, but that will take
time than I'll spend this evening :-) Quick hits below...
Good to hear you might look into it after all ;)
but at the end of the day, if we've got a 12 hour rebuild (fairly conservative
in the days of 2TB
SATA drives), the performance degradation is going to be very real for
I'd like to see some data on this for modern ZFS implementations (post Summer
Is "scrubbing performance" irrelevant in this discussion?
I think that in general, scrubbing is the read-half of
a larger rebuild process, at least for a single-vdev pool,
so rebuilds are about as long or worse. Am I wrong?
In my home-NAS case a raidz2 pool of six 2Tb drives, which
is filled 76%, consistently takes 85 hours to scrub.
No SSDs involved, no L2ARC, no ZILs. According to iostat,
the HDDs are often utilized to 100% with random IO load,
yielding from 500KBps to 2-3MBps in about 80-100IOPS per
disk (I have a scrub going on at this moment).
This system variably runs oi_148a (LiveUSB recovery) and
oi_151a when alive ;)
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