ZFS on root and disk write caching.

[Arnaud Houdelette]

I'm playing around with ZFS.

Currently, I just use it for storage, with a zpool of 4 sata disks.
The system and boot disk is still formatted with UFS.

As I'm quite pleased with ZFS features, I'd like to try ZFS on root. The 
ZFS wiki is quite clear on how to proceed : if the boot and root are on 
the same disk, you'll have to use bsd labels.

The thing is, I read somewhere that ZFS doesn't enable write caching on 
drives if not used on whole disks.

1. Is it still true on freebsd or just for opensolaris.
2. As the only other(s) label(s) on disk would be the (readonly) boot 
and swap label, I don't think write caching would be a problem. So how 
can I tell ZFS it's ok to enable it on the disk (or enable it manualy if 
necessary and of any use).
3. I'd like to keep the storage pool (zraid1) separated from the system 
pool (just one disk). The wiki states that we may encounter problems 
with more than one pool in use : is it still the case ?

I know the whole ZFS thing is still experimental, but with it's overall 
performance, it would really be a shame not to give it its chance.

Thanks for your comments.

Arnaud Houdelette