> Did you do any FILE devclass work?  It sounds as though your miserable
> performance was head thrashing, which we'd get in multiple LV DISK
> devclasses, and also in FILE devclasses.  Darn. :)

No I was using a DISK devclass, but I'm almost positive it wouldn't have
made any difference with FILE devclasses.  Some of the LUNs were faster
than others (first ones in the RAID group created) and as soon as I was
writing to more than one at a time my performance would tank even further,
which shouldn't be any different had I used FILE devclasses.  I would have
tried file devclasses with more time for performance reasons, but I had
spent too much time on it already and the 150 MB/sec writes for my
diskpool was adequate for my needs and outpaced the capabilities of my
single Gigabit network connection to the TSM server, so I moved on.

Hundreds of LVs with FILE devclasses on fibre disks would probably do
exactly what you are looking for and provide excellent performance.  SATA
just isn't good enough at multiple, simultaneous I/Os to the same set of
disks yet.