8.2-RC1 and ZFS

Marco van Tol marco at tols.org
Thu Dec 30 08:57:27 UTC 2010


On Wed, Dec 29, 2010 at 05:11:32PM -0700, David Samms wrote:
> I gave ZFS a try again this afternoon and immediately came across what I 
> would consider a problem.  Simply running dd causes such IO contention 
> that a GUI desktop is unusable and MP3s stop playing.  The problem is 
> very repeatable, just run dd if=/dev/zero of=big bs=1m count=6400
> 
> System is amd64, source updated Dec 27.  Default ZFS parameters. (no 
> tuning).  With the same system but UFS+s dd causes no problems.

Check out this mail from Jeremy Chadwick from December 28th in
freebsd-stable at .
http://docs.freebsd.org/cgi/getmsg.cgi?fetch=312384+0+current/freebsd-stable

I think specifically the comments and tweaks regarding
vfs.zfs.txg.timeout="5" and vfs.zfs.txg.write_limit_override=1073741824
should be usefull for you. :-)

I'm intentionally not touching the subject why you see what you do
without tuning.  I'm sure there are a great bunch of different
situations for which the defaults are the way they are.

:-)

Marco van Tol

-- 
"Van Duitsers heb je pas gewonnen als ze met de bus de stad uit zijn."
- Youp van 't Hek


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