ZFS "stalls" -- and maybe we should be talking about defaults?

[Ben Morrow]

Quoth Karl Denninger <karl at denninger.net>:
> 
> Note that the machine is not booting from ZFS -- it is booting from and
> has its swap on a UFS 2-drive mirror (handled by the disk adapter; looks
> like a single "da0" drive to the OS) and that drive stalls as well when
> it freezes.  It's definitely a kernel thing when it happens as the OS
> would otherwise not have locked (just I/O to the user partitions) -- but
> it does. 

Is it still the case that mixing UFS and ZFS can cause problems, or were
they all fixed? I remember a while ago (before the arc usage monitoring
code was added) there were a number of reports of serious probles
running an rsync from UFS to ZFS.

If you can it might be worth trying your scratch machine booting from
ZFS. Probably the best way is to leave your swap partition where it is
(IMHO it's not worth trying to swap onto a zvol) and convert the UFS
partition into a separate zpool to boot from. You will also need to
replace the boot blocks; assuming you're using GPT you can do this with
gpart bootcode -p /boot/gptzfsboot -i <gpt boot partition>.

Ben