In the last episode (Dec 19), Stefan Esser said: > for quite some time I have observed an uneven distribution of load between > drives in a 4 * 2TB RAIDZ1 pool. The following is an excerpt of a longer > log of 10 second averages logged with gstat: > > dT: 10.001s w: 10.000s filter: ^a?da?.$ > L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name > 0 130 106 4134 4.5 23 1033 5.2 48.8| ada0 > 0 131 111 3784 4.2 19 1007 4.0 47.6| ada1 > 0 90 66 2219 4.5 24 1031 5.1 31.7| ada2 > 1 81 58 2007 4.6 22 1023 2.3 28.1| ada3 [...] > zpool status -v > pool: raid1 > state: ONLINE > scan: none requested > config: > > NAME STATE READ WRITE CKSUM > raid1 ONLINE 0 0 0 > raidz1-0 ONLINE 0 0 0 > ada0p2 ONLINE 0 0 0 > ada1p2 ONLINE 0 0 0 > ada2p2 ONLINE 0 0 0 > ada3p2 ONLINE 0 0 0 Any read from your raidz device will hit three disks (the checksum is applied across the stripe, not on each block, so a full stripe is always read) so I think your extra IOs are coming from somewhere else. What's on p1 on these disks? Could that be the cause of your extra I/Os? Does "zpool iostat -v 10" give you even numbers across all disks? -- Dan Nelson dnelson_at_allantgroup.comReceived on Mon Dec 19 2011 - 15:40:39 UTC
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