ZFS performance degradation over time

[Erwin Lansing]

On Wed, Jan 20, 2010 at 11:47:30AM +0100, Alexander Leidinger wrote:
> 
> Quoting Jeremy Chadwick <freebsd at jdc.parodius.com> (from Tue, 19 Jan  
> 2010 09:01:01 -0800):
> 
> > I've two recommendations:
> >
> > 1) Have you considered "upgrading" to RELENG_8 (e.g. 8.0-STABLE) instead
> > of sticking with 8.0-RELEASE?  There's been a recent MFC to RELENG_8
> > which pertain to ARC drainage.  I'm referring to the commit labelled
> > revision 1.22.2.2 (RELENG_8):
> >
> > http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
> 
> This patch can be merged stand-alone if necessary, no need to go to  
> RELENG_8 if there are reservations.
> 
> The commit you refer to above is just doing this: limiting the arc  
> more to the arc_max than it was the case before.
> 
> This patch is in 7-stable too (in case someone is interested).
> 
Two weeks ago, we started experiencing similar symptoms on the pointyhat
package cluster.   This was on 9.0-CURRENT from last September.  Upgrading
to last weeks HEAD has solved the problem for us.  The system is heavily
loaded both on CPU, memory and disk, and since the original patch was
committed back in October, my guess is that it was this specific commit
that solved the issue.  I'd recommend people still experiencing this
issue to upgrade to a system that includes this change, be it 8.0-STABLE
or 7.2-STABLE after January 8, or manually merging it.

Cheers,
-erwin

-- 
Erwin Lansing                                   http://droso.org
Prediction is very difficult
especially about the future                    erwin at FreeBSD.org
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