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Date:      Fri, 06 Nov 2009 14:11:54 -0700
From:      Michael Loftis <mloftis@wgops.com>
To:        freebsd-stable@freebsd.org
Subject:   Re: Performance issues with 8.0 ZFS and sendfile/lighttpd
Message-ID:  <94A540AC0E2A75B7CA3ED7F7@[192.168.1.44]>
In-Reply-To: <696A0DF1-020B-48CB-BF38-6605EAD5BF1E@wanderview.com>
References:  <772532900-1257123963-cardhu_decombobulator_blackberry.rim.net-1402739480-@bda715.bisx.prod.on.blackberry> <hcma4s$c49$1@ger.gmane.org>	<4AEEBD4B.1050407@quip.cz> <hcmhbj$40s$1@ger.gmane.org> <5275583A0E66749DA096A22F@[192.168.1.44]> <696A0DF1-020B-48CB-BF38-6605EAD5BF1E@wanderview.com>

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--On Friday, November 06, 2009 3:31 PM -0500 Ben Kelly <ben@wanderview.com> 
wrote:

> Have you tried adjusting vfs.zfs.arc_meta_limit?  I've noticed the
> default value for this is set poorly when the overall ARC size is small.
> This happens because various structure's not actually allocated from the
> ARC like dnodes and dbufs are included in the metadata usage stats.  When
> the ARC is large this is somewhat negligible, but for small ARCs it
> overwhelms the calculated default metadata limit and you end up not
> caching any real file system metadata.
>
> You could try increasing the metadata limit or even better increase your
> maximum ARC size to something over 1GB.  (I seem to remember your ARC
> size is 128M from earlier in the thread).

Nope, that was someone else, not setting any ARC limits (or any ZFS 
settings at all actually).

>
> Hope that helps.
>
> - Ben
>







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