8.1 amd64 lockup (maybe zfs or disk related)

[Patrick M. Hausen]

Hello,

Am 08.02.2011 um 16:00 schrieb Tom Evans:
> My home file server is similar in spec to that - Core 2 Duo, 4 GB RAM
> and running 8.2-RC3/amd64, with a pool with two 6 x 1.5 TB raidz
> arrays, for a total capacity of ~16 TB. The only ZFS settings I have
> changed from default are:
> 
> # Allow prefetch (normally disabled for 4GB or less RAM)
> vfs.zfs.prefetch_disable=0
> # Don't let ZFS use UMA, restricts available memory
> vfs.zfs.zio.use_uma=0
> 
> I think vfs.zfs.zio.use_uma defaults to 0 now anyway.
> 
> I've never had a crash related to memory pressure or any other ZFS
> issue - it doesn't get that stressed. YMMV!

Yes, it may - and it does ;-)

With no tuning at all my FreeNAS (FreeBSD 7.3, amd64, 4 GB RAM, 4 TB raidz2)
crashes within minutes if I copy larger amounts of data via SMB or AFP to the
ZFS. 

With these settings it's perfectly stable, but I figured from Jeremy's that they
might not be optimal:

vm.kmem_size_max="1024M"
vm.kmem_size="1024M"
vfs.zfs.arc_max="100M"
vfs.zfs.prefetch_disable="0"

And with the very same settings on our bigger backup box I really need to
improve performance somehow. We are backing up >50 hosts nightly with
Amanda. I got from this post that I definitely should increase memory on
this machine:

http://constantin.glez.de/blog/2010/06/closer-look-zfs-vdevs-and-performance


Kind regards,
Patrick
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