ZFSv28+NFSv4 poor file creation performance, "sync=disabled" has no effect

[Pawel Jakub Dawidek]

On Fri, Sep 02, 2011 at 09:29:33AM -0700, David Brodbeck wrote:
> I originally posted this on FreeBSD-questions, but it was suggested that I
> bring it here.
> I'm testing FreeBSD 9.0-BETA with an eye toward eventually using
> FreeBSD 9.0 to replace some existing OpenSolaris 2008.11
> installations.  I've found NFS file creation performance (as measured
> by Bonnie++) is equally slow for both with default settings.  However,
> on OpenSolaris I disable the ZIL to improve file creation performance.
>  This tuning parameter was removed from FreeBSD 9.0; its replacement
> is supposed to be the per-filesystem flag "sync", but setting this
> flag seems to have no effect.
> 
> I did recompile the FreeBSD kernel without debugging features before
> doing the tests, so I don't think this is a case of debugging code
> slowing things down.
> 
> Here's the relevant data; these are all from bonnie++'s "sequential
> create" benchmark.  The NFS client was RedHat Enterprise Linux 5.6.
> 
> OpenSolaris 2008.11, default settings: 58/second
> OpenSolaris 2008.11, with "zil_disable=1": 1258/second
> 
> FreeBSD 9.0-BETA, default settings: 107/second
> FreeBSD 9.0-BETA, with "sync=disabled": 106/second
> 
> So it appears the "sync" ZFS parameter has no effect in FreeBSD.  Has
> anyone else seen this?  Is there a way to improve NFS file creation
> performance now that zil_disable has been removed?

It would be good if you could try your test on FreeBSD directly. This
way we could see if ZFS is to blame or NFS.

-- 
Pawel Jakub Dawidek                       http://www.wheelsystems.com
FreeBSD committer                         http://www.FreeBSD.org
Am I Evil? Yes, I Am!                     http://yomoli.com
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