On Thu, Nov 23, 2006 at 12:09:09PM +0100, Pawel Jakub Dawidek wrote: > 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.
Oops, you operate on partitions... I think for partitions ZFS disables write cache on disks... Anyway, I'll leave the answer to someone more clueful. -- 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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