Many processes stuck in zfs

[Borja Marcos]

On Mar 9, 2010, at 1:29 PM, Pawel Jakub Dawidek wrote:

> On Tue, Mar 09, 2010 at 10:15:53AM +0100, Stefan Bethke wrote:
>> Over the past couple of months, I've more or less regularly observed machines having more and more processes stuck in the zfs wchan.  The processes never recover from that, and trying to reboot only gets the entire system stuck, without any console messages.  I can enter the debugger, and I have saved a couple of dumps.
>> 
>> The situation seems to be triggered by zfs receive'ing snapshots from the sister machine (both synchronize their active ZFS filesystems to each other, using zfs send and zfs receive).  It appears it's the receiving causing trouble.
>> 
>> Both machines run 8-stable from mid-February, with a single-disk ZFS pool, with ARC limited to 512M, prefetch and ZIL disabled via loader.conf.
>> 
>> What should I be looking at to further diagnose?
> 
> What kind of hardware do you have there? There is 3-way deadlock I've a
> fix for which would be hard to trigger on single or dual core machines.
> 
> Feel free to try the fix:
> 
> 	http://people.freebsd.org/~pjd/patches/zfs_3way_deadlock.patch

Maybe related to the deadlock I reported when I was receiving an incremental snapshot while the target dataset was being read?





Borja.