Anyone using freebsd ZFS for large storage servers?

Daniel Staal DStaal at
Thu May 31 23:33:46 UTC 2012

--As of May 31, 2012 11:24:41 AM -0700, Dennis Glatting is alleged to have 

> 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:

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

This email copyright the author.  Unless otherwise noted, you
are expressly allowed to retransmit, quote, or otherwise use
the contents for non-commercial purposes.  This copyright will
expire 5 years after the author's death, or in 30 years,
whichever is longer, unless such a period is in excess of
local copyright law.

More information about the freebsd-questions mailing list