Slow disk write IO with ZFS / NFS
Andrew Snow
andrew at modulus.org
Fri Sep 25 23:51:39 UTC 2009
Scott Ullrich wrote:
> Does anyone have any pointers on how to speed this up without putting
> the data in jeopardy during a power failure, etc (ie: leaving ZIL on).
NFS writes are syncronous so ZFS is constantly syncing small datablocks
to disk. By default the transaction log is stored on the same disks as
the rest of the data.
You might like to try an async NFS mount, but this isn't much different
from just turning off the ZIL.
Failing that, Add a log device to the pool, SSD or ramdisk is ideal, but
separate disk HDD spindles to your data zpool also works pretty well.
- Andrew
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