On 09/12/15 01:04, Michael B. Eichorn wrote:
On Tue, 2015-12-08 at 16:31 -0600, Dustin Wenz wrote:
I suspect this is a zfs bug that is triggered by the access patterns
in the periodic scripts. There is significant load on the system when
the scheduled processes start, because all jails execute the same
scripts at the same time.
I've been able to alleviate this problem by disabling the security
scans within the jails, but leave it enabled on the root host.
To avoid the problem of jails all starting things at the same time, use
the cron(8) flags -j and -J to set a 'jitter' which will cause cron to
sleep for a random period of specified duration (60 sec max). Cron
flags can be set using the rc.conf variable 'cron_flags'.
While jitter would reduce the resource contention a thundering herd of
cronjobs shouldn't cause the kernel to divide by zero. Spreading the
load by introducing jitter to cronjobs might hide the problem, but it
still needs further analysis.
@Dustin Wenz: Can you reproduce the problem and file a PR to track this?
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