There are a bunch of things to consider, but I agree with James, don't
create two dev classes.  You won't have a conflict with tape drives anyway
if you do things correctly.  End of day processing should proceed as
follows, with each step completing before the next begins:

1. backup stg diskpool copypool maxprocess=# of drives
2. backup stg tapepool copypool maxprocess=# of drives/2
3. update stg diskpool highmig=0 lowmig=0 migproc=# of drives (this
migrates the data from disk to tape)
4. expire inventory
5. backup db
6. backup volhist file=some offsitable media
7. backup devconfig file=some offsitable media
8. prepare (if using DRM)

The position of expire inventory is somewhat debatable, but the rest should
be done in this order.  If you have multiple storage pool hierarchies,
repeat 1-3 for each hierarchy.

Kelly J. Lipp
Storage Solutions Specialists, Inc.
www.storsol.com
lipp AT storsol DOT com
(719)531-5926