I could see a situation where the disk array is legacy and no money has
been spent to upgrade it. It sound curiously like someone making due
with what they had and trying to distribute the I/O in any way possible.

Richard Sims wrote:

Hi, Paul -

You have your work cut out for you with that train-wreck of a system.
I'd begin by questioning the need for all that DB content... There
may be abandoned filespaces which should go, obsolete retention
periods which no one has looked at in years, and perhaps even
Expirations which never run to completion.
As to performance, I'd begin by inspecting SCSI topology, to assure
no dumb stuff, like tape and disk on the same cable. Next I'd review
the LTO microcode levels, as older levels had serious problems (see
"LTO performance" in ADSM QuickFacts). The "sleep" may be the drive
struggling to load and position the tape. You might consider a tape
case study using the tapeutil command, or the like, to get some
baseline numbers on the performance of those drives and tapes for
comparison as improvements are pursued.

The disk layout certainly needs a lot of review, as it doesn't seem
to make sense, even if one is not familiar with EMC boxes.

Only as very last resort would I even consider db unload/reload:
that's ill-advised even in the best of circumstances, as proven
dangerous and often unproductive.

   Richard Sims