current zfs tuning in RELENG_7 (AMD64) suggestions ?

[Mike Tancsa]

At 04:53 PM 5/1/2009, Pete French wrote:

>The tuning isn't there to improve performance, it's there to prevent
>the box going titus due to a panic when the ARC gets too big, and
>you are missing the mian one, which is to limit the size of the ARC.
>On recent versions of BSD (and you are running 7.2, so thats fine) then
>the defaults for kmem size are fine, but you still need something like this:
>
>vfs.zfs.arc_max="256M"
>
>In there to stop the ARC growing. thats the only tuning I have on
>my 4 gig machine, which takes a steady stream of data and is used
>for taking backup snapshots. ZFS is excellent, and for me is perfectly
>stable, to the point where I am starting to roll it out to production
>machines, with the above tuning.


Thanks for the feedback.  We too have had good results with zfs for 
what we have used it for.  Our primary backup server has a 
traditional raid5 spool as well as a zfs spool and it has been 
working quite well in the last 6months. In that period we did swap 
out a dead drive, a dying drive and added a new drive to expand the 
pool.  We are just expanding our DR site's backup server and will 
make use of ZFS there.  Stability / reliability is our main goal for 
this app so I will take a look at the arc_max setting

         ---Mike