On Wed, Nov 22, 2006 at 03:38:05AM -0800, Peter Eriksson wrote: > There is nothing in the ZFS FAQ about this. I also fail to see how FMA could > make any difference since it seems that ZFS is deadlocking somewhere in the > kernel when this happens... > > It works if you wrap all the physical devices inside SVM metadevices and use > those for your > ZFS/zpool instead. Ie: > > metainit d101 1 1 c1t5d0s0 > metainit d102 1 1 c1t5d1s0 > metainit d103 1 1 c1t5d2s0 > zpool create foo radz /dev/md/dsk/d101 /dev/md/dsk/d102 /dev/md/dsk/d103 > > Another unrelated observation - I've noticed that ZFS often works *faster* if > I wrap a physical partition inside a metadevice and then feed that to zpool > instead of using the raw partition directly with zpool... Example: Testing > ZFS on a spare 40GB partition of the boot ATA disk in an Sun Ultra 10/440 > gives horrible performance numbers. If I wrap that into a simple metadevice > and feed to ZFS things work much faster... Ie: > > Zpool containing one normal disk partition: > > # /bin/time mkfile 1G 1G > real 2:46.5 > user 0.4 > sys 24.1 > --> 6MB/s (that was actually the best number I got - the worst was 3:03 > minutes) > > Zpool containing one SVM metadevice containing the same disk partition: > > #/bin/time mkfile 1G 1G > real 1:41.6 > user 0.3 > sys 23.3 > --> 10MB/s > > (Idle machine in both cases, mkfile rerun a couple of times, with the same > results. I removed the 1G file between reruns of course)
It may be because for raw disks ZFS flushes write cache (via DKIOCFLUSHWRITECACHE), which can be expensive operation and highly depend on disks/controllers used. I doubt it does the same for metadevices, but I may be wrong. -- Pawel Jakub Dawidek http://www.wheel.pl [EMAIL PROTECTED] http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am!
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