ZFS on a single disk?

[Jeremy Chadwick]

On Wed, Mar 02, 2011 at 12:00:24AM +0000, Dr Josef Karthauser wrote:
> On 1 Mar 2011, at 23:49, Mark Blackman wrote:
> > 
> > On 1 Mar 2011, at 23:27, Dr Josef Karthauser wrote:
> > 
> >> Does it make sense to run zfs on a single disk?
> >> 
> >> I'm setting up a FreeBSD host over at a Xen provider, with a single 80GB disk image. Ideally I'd like to run ZFS on this system, for snapshot and flexible creation of filesystems and quotas. Has anyone got any recommendations for me in this regard? Am I crazy?
> > 
> > Not crazy, I do this as well, all the time just to get the management capabilities and
> > leave hardware RAID to manage the availability.
> > 
> > - Mark
> 
> Any idea what the performance implications are? Can I get away without a ZIL or ARC and still get a decent performance?

Do not disable the ZIL.  I hate referring to the Solaris documentation
for FreeBSD, but it applies:

http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide#Disabling_the_ZIL_.28Don.27t.29

And you cannot disable the ARC, so just tune it appropriately (which
you'll need to do on FreeBSD anyway).  In fact, by getting rid of the
ARC (as you proposed), you would suffer worse performance than if you
had it in use.

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.               PGP 4BD6C0CB |