Anyone using freebsd ZFS for large storage servers?

Dennis Glatting freebsd at
Fri Jun 1 00:34:17 UTC 2012

On Thu, 2012-05-31 at 19:27 -0400, Daniel Staal wrote:
> --As of May 31, 2012 11:24:41 AM -0700, Dennis Glatting is alleged to have 
> said:
> > 2) Under heavy I/O my systems freeze for a few seconds. I haven't looked
> > into why but they are completely unresponsive. Note I am also using
> > compressed volumes (gzip), which puts a substantual load on the kernel.
> --As for the rest, it is mine.
> I'm not using as huge a dataset, but I was seeing this behavior as well 
> when I first set my box up.  What was happening was that ZFS was caching 
> *lots* of writes, and then would dump them all to disk at once, during 
> which time the computer was completely occupied with the disk I/O.
> The solution (suggested from <>) for 
> me was:
> vfs.zfs.txg.timeout="5"

Was already set:

mc# sysctl vfs.zfs.txg.timeout
vfs.zfs.txg.timeout: 5

> in loader.conf.  That only allows it to cache writes for 5 seconds, instead 
> of the default 30.  This appears to be the default in the latest versions 
> of FreeBSD, so if you are running an upgraded 9, ignore me.  ;)  (But check 
> the page linked above: There are other suggestions to try.)
> Daniel T. Staal
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