I would assume the goal here is to speed the restoration process.  The only
way to guarantee that happens is to ensure you don't have tape contention
during the restore.  At the directory level that is hard unless you use
multiple management classes and tape storage pools.

This points out the larger problem in fine detail.  If you want to do
multiple simultaneous restores you must plan for them during backup.  As
manufacturers introduce 72GB drives, we're going to see enormous RAID sets
(we are already seeing enormous sets but this will make them enormouser -
new word my prerogative).  You should/must break these large sets into
multiple filespaces and then use collocate=filespace on your storage pools.
I would guess the best restore times you are likely to see will be around
10GB/hour/stream.  If you have a 360GB single filespace RAID set you can
expect a restore time ~36 hours.  You are being foolish to expect faster.
The tape drive spec types will crawl out the woodwork and tell us that the
drives can restore much more than that per hour.  Sure, but unfortunately
we're dealing with reality here and not the spec sheets.  There are many
other factors influencing how fast we move data.

I know, I know, breaking the big drive into smaller ones means more
management.  As long as you don't ever need to restore it creating a mongo
drive is easiest thing to do.  Just remember you did this because you never
were going to restore it.  Try to remember that in the middle of the second
day while you're trying to restore it.

Let's bring some rationality back to our business.  Bigger isn't always
better.

Kelly J. Lipp
Storage Solutions Specialists, Inc.
PO Box 51313
Colorado Springs CO 80949-1313
(719) 531-5926
Fax: (240) 539-7175
Email: lipp AT storsol DOT com or lipp AT storserver DOT com
www.storsol.com
www.storserver.com