We simply def additional disk volumes using
add vol to volume group
either make logical volume or format a volume
define volume stgpool filename formatsize=xxx

We had an expert come in and he reccommended partitioning our disks into
multiple segments and having several segments like on an 8 gig disk having 4
2gig volumes of storage.  That was for performance.  You probably won't need
to do that with the shark depending on how you set it up.  Please let me
know how that works performance wise with the shark because we just got one
and will be doing that to a certain degree in the near future.  Another
performance boost that we got was on my disk pool I don't start migration
until 75% and then I go down to 1.  This has more time to dump to disk with
less migration going.  It usually keeps up.