Unkillable and runaway processes

[Dan Nelson]

In the last episode (Sep 04), Kenneth Vestergaard Schmidt said:
> Our ZFS testbed is experiencing some weird problems with rsync. We
> run a nightly backup of about 1.6 TB data (that's how much is stored,
> not how much is transferred), but after the initial sync I haven't
> been able to get the machine through one full cycle.
> 
> After many hours of rsyncing data from 50+ machines, suddenly one
> rsync-process will hang, spinning on the CPU.
> 
> It switches state between CPU0, CPU1, RUN and 'zfs:(&', but doesn't
> really do anything. It can't be killed, and you can't reboot the
> machine - it'll get past syncing disks, but won't shutdown or reboot.

The zfs wchan strings are way too long for ps or top to print, but if
the rsync is running from a tty somewhere, hit ^T and you'll get the
full wait string.

-- 
	Dan Nelson
	dnelson at allantgroup.com