Another option to look at is: set zfs:zfs_nocacheflush=1 http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide
Best option is to get a a fast ZIL log device. Depends on your pool as well. NFS+ZFS means zfs will wait for write completes before responding to a sync NFS write ops. If you have a RAIDZ array, writes will be slower than a RAID10 style pool. On Tue, Jan 20, 2009 at 11:08 AM, Greg Mason <gma...@msu.edu> wrote: > We're running into a performance problem with ZFS over NFS. When working > with many small files (i.e. unpacking a tar file with source code), a > Thor (over NFS) is about 4 times slower than our aging existing storage > solution, which isn't exactly speedy to begin with (17 minutes versus 3 > minutes). > > We took a rough stab in the dark, and started to examine whether or not > it was the ZIL. > > Performing IO tests locally on the Thor shows no real IO problems, but > running IO tests over NFS, specifically, with many smaller files we see > a significant performance hit. > > Just to rule in or out the ZIL as a factor, we disabled it, and ran the > test again. It completed in just under a minute, around 3 times faster > than our existing storage. This was more like it! > > Are there any tunables for the ZIL to try to speed things up? Or would > it be best to look into using a high-speed SSD for the log device? > > And, yes, I already know that turning off the ZIL is a Really Bad Idea. > We do, however, need to provide our users with a certain level of > performance, and what we've got with the ZIL on the pool is completely > unacceptable. > > Thanks for any pointers you may have... >
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