Spontaneous reboots on Intel i5 and FreeBSD 9.0

[John]

>At 03:00am I can see that periodic(8) runs, but I don't see what could have
>taken so much of the free memory. I'm also running this system on ZFS and
>have daily rotating ZFS snapshots created - currently the number of ZFS
>snapshots are > 1000, and not sure if that could be causing this. Here's a
>list of the periodic(8) daily scripts that run at 03:00am time.
>
>% ls -1 /etc/periodic/daily
>800.scrub-zfs
>
>% ls -1 /usr/local/etc/periodic/daily
>402.zfSnap
>403.zfSnap_delete

On a couple of my zfs machines, I've found running a scrub along with other
high file system users to be a problem.  I therefore run scrub from cron and
schedule it so it doesn't overlap with periodic.

I also found on a machine with an i3 and 4G ram that overlapping scrubs and
snapshot destroy would cause the machine to grind to the point of being
non-responsive. This was not a problem when the machine was new, but became one
as the pool got larger (dedup is off and the pool is at 45% capacity).

I use my own zfs management script and it prevents snapshot destroys from
overlapping scrubs, and with a lockfile it prevents a new destroy from being
initiated when an old one is still running.

zfSnap has its -S switch to prevent actions during a scrub which you should
use if you haven't already.

Since making these changes, a machine that would have to be rebooted several
times a week has now been up 61 days.

John Theus
TheUs Group