Uneven load on drives in ZFS RAIDZ1

[Stefan Esser]

Am 19.12.2011 19:03, schrieb Daniel Kalchev:
> I have observed similar behavior, even more extreme on a spool with dedup enabled. Is dedup enabled on this spool?

Thank you for the report!

Well, I had dedup enabled for a few short tests. But since I have got
"only" 8GB of RAM and dedup seems to require an order of magnitude more
to be working well, I switched dedup off again after a few hours.

> Might be that the DDT tables somehow end up unevenly distributed to disks. My observation was on a 6 disk raidz2.

Hmmm, there was another report of even distribution of load on a 6 disk
raidz1 (but in fact, in that case the first half seems to have got some
10% to 15 higher load than the second half; the sixth drive showed quite
different queue length and latencies and I think these might be caused
either by a defect (soft-errors) or another partition being actively
used only on that drive).

Regards, STefan