On Thu, May 20, 2010 13:58, Roy Sigurd Karlsbakk wrote:
> ----- "Travis Tabbal" <tra...@tabbal.net> skrev:
>
>> Disable ZIL and test again. NFS does a lot of sync writes and kills
>> performance. Disabling ZIL (or using the synchronicity option if a
>> build with that ever comes out) will prevent that behavior, and should
>> get your NFS performance close to local. It's up to you if you want to
>> leave it that way. There are reasons not to as well. NFS clients can
>> get corrupted views of the filesystem should the server go down before
>> a write flush is completed. ZIL prevents that problem. In my case, the
>> clients aren't on a UPS while the server is, so it's not an issue. :)
>
> Disabling ZIL is, according to ZFS best practice, NOT recommended. Get
> some SSD for the Zil instead, preferably mirrored. You won't need a lot,
> ZIL never uses more than half the RAM size
Disabling the ZIL is an easy way to TEST whether a ZIL would be helpful.
If things speed up after turning it off, then you'd turn it back on, and
go and purchase an SSD.
There's no sense spending money if it won't fix the problem.
To the OP, see Section 2.7 ("Disabling the ZIL (Don't)") of:
http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide
As mentioned, you do NOT want to run with this in production, but it is a
quick way to check.
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