ZFS boot

[Pegasus Mc Cleaft]

On Saturday 11 October 2008 21:53:35 Nate Eldredge wrote:
> On Sat, 11 Oct 2008, Freddie Cash wrote:
> > On 10/11/08, Matthew Dillon <dillon at apollo.backplane.com> wrote:
> >>     With regards to the traditional BSD partitioning scheme, having a
> >>     separate /usr, /home, /tmp, etc... there's no reason to do that
> >> stuff any more with ZFS (or HAMMER).
> >
> > As separate partitions, no.  As separate filesystems, definitely.
> >
> > While HAMMER PFSes may not support these things yet, ZFS allows you to
> > tailor each filesystem to its purpose.  For example, you can enable
> > compression on /usr/ports, but have a separate /usr/ports/distfilles
> > and /usr/ports/work that aren't compressed.  Or /usr/src compressed
> > and /usr/obj not.  Have a small record (block) size for /usr/src, but
> > a larger one for /home.  Give each user a separate filesystem for
> > their /home/<username>, with separate snapshot policies, quotas, and
> > reservations (initial filesystem size).
>
> All this about ZFS sounds great, and I'd like to try it out, but some of
> the bugs, etc, listed at http://wiki.freebsd.org/ZFSKnownProblems are
> rather alarming.  Even on a personal machine, I don't want these features
> at the cost of an unstable system.  Is that list still current?

	I dont know if that list is completely accurate any more, but I can tell you 
from my own personal experience with ZFS that it has been quite good. I have 
two servers (one is my test-bed at home) and the other is a production server 
running mostly mysql at work and I have never experienced the dead-locking 
problem. 


>
> FWIW, my system is amd64 with 1 G of memory, which the page implies is
> insufficient.  Is it really?

	This may be purely subjective, as I have never bench marked the speeds, but 
when I was first testing zfs on a i386 machine with 1gig ram, I thought the 
performance was mediocre. However, when I loaded the system on a quad core - 
core2 with 8 gigs ram, I was quite impressed. I put localized changes in my 
/boot/loader.conf to give the kernel more breathing room and disabled the 
prefetch for zfs. 

#more loader.conf
vm.kmem_size_max="1073741824"
vm.kmem_size="1073741824"
vfs.zfs.prefetch_disable=1

	The best advice I can give is for you to find an old machine and test-bed zfs 
for yourself. I personally have been pleased with it and It has saved my 
machines data 4 times already (dieing hardware, unexpected power bounces, etc) 

	As a side note, my production machine boots off a dedicated UFS drive (where 
I also have a slice for the swap). /usr, /var, /var/db and /usr/home are zfs.  
My test server at home only has /usr/home as zfs. I found it easier for me, 
when I kill the home machine to just do a reload/rebuild of the OS,  rebuild 
the applications, and rechown/grp the home directories. 

Peg