Date: Fri, 3 Sep 2010 18:09:43 -0700 From: Artem Belevich <fbsdlist@src.cx> To: Steven Hartland <killing@multiplay.co.uk> Cc: freebsd-fs@freebsd.org Subject: Re: zfs very poor performance compared to ufs due to lack of cache? Message-ID: <AANLkTi=6bta-Obrh2ejLCHENEbhV5stbMsvfek3Ki4ba@mail.gmail.com> In-Reply-To: <5DB6E7C798E44D33A05673F4B773405E@multiplay.co.uk> References: <5DB6E7C798E44D33A05673F4B773405E@multiplay.co.uk>
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> For reference top shows:- > Mem: 42M Active, 3129M Inact, 565M Wired, 3188K Cache, 19M Buf, 203M Free Here's your problem -- inactive list got all your memory and starved ZFS ARC. Easy workaround is to set vfs.zfs.arc_min to a value that would guarantee that ARC does not give up too much memory. Let's say - 2GB. Be warned that it would effectively make those 2GB unavailable to applications. Long term, though, there were number of patches posted on freebsd-current and freebsd-hackers recently that do improve that particular issue with ZFS. This patch in particular may help you: http://lists.freebsd.org/pipermail/freebsd-hackers/2010-August/032731.html > Swap: 4096M Total, 1180K Used, 4095M Free > > So what are we missing and how to we get zfs to perform like ufs > and use all free ram as cache? --Artem
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