Re: HEADS UP: New ZFS in the tree.

Hello Stefan

Am 04.12.2008 um 00:33 schrieb Stefan Bethke:
> Am 03.12.2008 um 00:29 schrieb Peter Schuller:
>
>>> I've noticed the past couple of days, when using the server (not  
>>> very
>>> often), every now and then, the GUI (KDE 4.1) will "hang" for up  
>>> to 5
>>> minutes (no mouse movement, no keyboard events), while the drives  
>>> work like
>>> crazy.
>>
>> I was not explicit about it, but FWIW in my case the hang is not due
>> to drive saturation. The drives were mostly idle (except some stuff
>> triggered by a buildworld I had going) during the extended period of
>> ktorrent being unkillable. But again I never had this happen
>> pre-CURRENT.
>
> Just a very brief "me too" (but possibly different effect): I'm  
> stress testing two machines I put together over the weekend with an  
> endless loop of make -j4 universe, with /usr/obj on ZFS, with a  
> single disk. One of the two machines has now been stuck for a couple  
> of hours, and trying to access /tank results in a hung process, as  
> will zfs list.
>
> I'll reboot and see what happens, and if I can trigger it again,  
> willt try to produce more details.
>
> I have set
> vfs.zfs.arc_max="512M"
> vfs.zfs.prefetch_disable=1
> in loader.conf
>
> FreeBSD lokschuppen.lassitu.de 8.0-CURRENT FreeBSD 8.0-CURRENT #1:  
> Wed Dec  3 07:05:03 UTC 2008     root_at_lokschuppen.lassitu.de:/usr/ 
> obj/usr/src/sys/EISENBOOT  amd64

Try to disable ZIL in loader.conf:
vfs.zfs.zil_disable="1"

It helped me to stop deadlocks during rsync processes. As long as you  
don't run any databases or any fsync() intensiv applications,  i don't  
see any drawbacks in disabling zil. The drawbacks are for the  
applications itself not for ZFS. ZFS will be always consistent on disk  
due to its transaction model even without ZIL.

Regards,
Thomas