Date: Mon, 19 Dec 2011 17:36:42 +0100 (CET) From: Michael Reifenberger <mike@reifenberger.com> To: Stefan Esser <se@freebsd.org> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: Uneven load on drives in ZFS RAIDZ1 Message-ID: <alpine.BSF.2.00.1112191724310.33692@gw.reifenberger.com> In-Reply-To: <4EEF488E.1030904@freebsd.org> References: <4EEF488E.1030904@freebsd.org>
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Hi,
a quick test using `dd if=/dev/zero of=/test ...` shows:
dT: 10.004s w: 10.000s filter: ^a?da?.$
L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name
0 378 0 0 12.5 376 36414 11.9 60.6| ada0
0 380 0 0 12.2 378 36501 11.8 60.0| ada1
0 382 0 0 7.7 380 36847 11.6 59.2| ada2
0 375 0 0 7.4 374 36164 9.6 51.3| ada3
0 377 0 1 10.2 375 36325 10.1 53.3| ada4
10 391 0 0 39.3 389 38064 15.7 80.2| ada5
Seems to be sufficiently equally distributed for a life system...
zpool status shows:
...
NAME STATE READ WRITE CKSUM
boot ONLINE 0 0 0
raidz1-0 ONLINE 0 0 0
ada0p3 ONLINE 0 0 0
ada1p3 ONLINE 0 0 0
ada2p3 ONLINE 0 0 0
ada3p3 ONLINE 0 0 0
ada4p3 ONLINE 0 0 0
ada5p3 ONLINE 0 0 0
...
The only cases I've seen (and expected to see) unequal load distributions on ZFS
was after extending a nearly full four disk mirror pool by additional two disks.
Bye/2
---
Michael Reifenberger
Michael@Reifenberger.com
http://www.Reifenberger.com
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