zfs very poor performance compared to ufs due to lack of cache?

[Steven Hartland]

----- Original Message ----- 
From: "Artem Belevich" <fbsdlist at src.cx>


>> 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

Thanks for that Artem, is there an way to tell what caused this starvation?

With the machine running only nginx, which uses next to nothing, I cant
think of anything which would have used the memory.

Hmmm could this have been caused by nfs as the volume is shared over standard
nfs as well.

    Regards
    Steve

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