Brad Plecs wrote:
I had a user report extreme slowness on a ZFS filesystem mounted over NFS over the weekend.
After some extensive testing, the extreme slowness appears to only occur when a ZFS filesystem is mounted over NFS.
One example is doing a 'gtar xzvf php-5.2.0.tar.gz'... over NFS onto a ZFS filesystem. this takes:
real 5m12.423s
user 0m0.936s
sys 0m4.760s
Locally on the server (to the same ZFS filesystem) takes:
real 0m4.415s
user 0m1.884s
sys 0m3.395s
The same job over NFS to a UFS filesystem takes
real 1m22.725s
user 0m0.901s
sys 0m4.479s
Same job locally on server to same UFS filesystem:
real 0m10.150s
user 0m2.121s
sys 0m4.953s
This is easily reproducible even with single large files, but the multiple small files
seems to illustrate some awful sync latency between each file.
Any idea why ZFS over NFS is so bad? I saw the threads that talk about an fsync penalty,
but they don't seem relevant since the local ZFS performance is quite good.
Known issue, discussed here:
http://www.opensolaris.org/jive/thread.jspa?threadID=14696&tstart=15
benr.
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