A copy pool is an exact replica of a primary storage pool.  Typically, a
backup stg operation is done daily with the resulting tape (along with the
db backup) being taken offsite for DR purposes.  In this fashion, you always
have all the data offsite.  With the scheme you laid out you would lose
perhaps a month's worth of data in the worst case.

I consulted at a site where they had three copy storage pools.  Each week,
they would backup stg their primary pools to a different copy storage pool.
When this operation was complete, they would take the entire set back
offsite.  Lots of tape spinning on a weekly basis.  Also, three sets of
tapes in the offsite.  Also, no ability to get back to yesterday in the
event of a disaster.

Your immediate concern is probably the amount of tapes you will have at the
offsite if you are taking one or more per day off.  Not to worry,
reclamation is used to keep the offsite pool a manageable size, perhaps
25-50% more tapes than you have in your primary pools.

The notion of copy storage pools is unique to *SM.  It works the way *SM
works: incrementals always even for copy storage pools.  So each day, only
the data that isn't already in the offsite pool is written to an offsite
volume.  Much easier than copying all of the data periodically.

Kelly J. Lipp
Storage Solutions Specialists, Inc.
PO Box 51313
Colorado Springs CO 80949-1313
(719) 531-5926
Fax: (719) 260-5991
Email: lipp AT storsol DOT com
www.storsol.com
www.storserver.com