HEADS UP: New ZFS in the tree.

Wes Morgan morganw at chemikals.org
Thu Dec 4 14:14:59 PST 2008

On Thu, 4 Dec 2008, Thomas Vogt wrote:

> 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.

Are you sure about that? Without the ZIL, wouldn't you need to scrub each 
pool after every crash, much as fsck with UFS?

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