"New" user with a possible ZFS problem

[Kevin Monceaux]

FreeBSD Fans,

Okay, I'm not exactly a "new" user.  I've been running FreeBSD for about a 
year or so on my web/mail server, which I only have remote access to. 
It's currently running 6.3.

Saturday I finally found one of those "round tuits" and switched my home 
PC from Debian to FreeBSD.  I've been a Linux user since the 1.xx Linux 
kernel days, so it took quite a bit of convincing myself to make the 
switch.  But other than needing to unlearn some bad habits I got into 
thanks to Linux, I'm feeling right at home.

After getting a taste of ZFS while trying out OpenSolaris Indiana under 
VMware, I decided to give FreeBSD's ZFS implementation a try.  Actually 
before installing FreeBSD I tried a native OpenSolaris Indiana install 
briefly, but ended up deciding it's new package system wasn't quite ready 
for prime time yet.

Do I really need ZFS?  Not really.  But after getting a taste of ZFS it'd 
be hard to go back to "regular" file systems.

I've had a couple of problems and I'm not sure if there ZFS related or 
not.

When I switched my PC to FreeBSD this past Saturday I went by the article 
located at:

http://www.ish.com.au/solutions/articles/freebsdzfs

to set up ZFS.  I followed the article's loader.conf tweaks advice and 
added:

vm.kmem_size_max="512M"
vm.kmem_size="512M"
vfs.zfs.zil_disable=1

to /boot/loader.conf.

All went well at first, then eventually I experienced my first hang.  If I 
remember correctly, I had an mp3 playing via mplayer and was moving a 
large file from one ZFS "partition" to another.  Both the mp3 player and 
mv command appeared to hang.  Checking top one of the processes was in a 
zfs:lo state and the other was, I think, in a zfs:&b state, or something 
similar.  I forget which was which.  Eventually they recovered. 
Eventually I encountered a similar hang with similar symptoms.  The second 
hang might have eventually recovered on it's own but I finally resorted to 
hitting the power switch.  After a little Googling on the process states I 
tried adding:

vfs.zfs.prefetch_disable="1"

to /boot/loader.conf.  After doing so I gave ZFS a bit of a workout.  I 
shuffled some large files around, etc., and all appeared well.

When I went to bed this morning, I had to work graveyards last night, I 
had an openoffice.org build running, which had been running for eight 
hours or so.  Okay, although I usually install everything from ports maybe 
I should go with the binary package for OpenOffice.  Anyway, when I got up 
this afternoon my PC was completely locked up.  I had no video signal, 
caps lock and num lock wouldn't change the keyboard LEDs, etc.  I finally 
resorted to hitting the power button.

After getting things back up, I freebsd-updated to 7.0-RELEASE-p2, after 
some Googling and commenting out the chflag calls in freebsd-update.  I 
know, I should have checked for updates right after I finished installing 
FreeBSD.

Anyway, does the above hangs all sound like they're ZFS related.  Are 
there any other settings I should try?  Is there a FreeBSD ZFS mailing 
list?  I searched but couldn't find one.




Kevin
http://www.RawFedDogs.net
http://www.WacoAgilityGroup.org
Bruceville, TX

Si hoc legere scis nimium eruditionis habes.
Longum iter est per praecepta, breve et efficax per exempla!!!