On Wed, 2015-12-09 at 11:24 +0100, Jan Bramkamp wrote: > > 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.
I concur, used the word 'avoid' in the sense that this was an improvement to his work-around (which is all that I quoted). I had no intent to imply that it was the solution to the bug, which of course deserves solving. Sorry for any confusion, I will try to be more clear in the future.
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