Backup is not your problem.  Restore is.  I recommend TSM over the WAN when
your large restore requirements (an entire disk or entire server) can be met
by rebuilding the failed object on-site where the server is and shipping the
restored object to the remote site.  If a disk fails, build a new disk near
the server and ship it overnight to the remote site.

For 99% of your restores, the WAN will function fine.  Perhaps a little slow
on large files, but acceptable compared with traditional GFS "send the tape
off-site" schemes.  Solve the other 1% problem by being clever and you're
all set.

Kelly J. Lipp
Storage Solutions Specialists, Inc.
PO Box 51313
Colorado Springs CO 80919
(719)531-5926
Fax: (719)260-5991
www.storsol.com
lipp AT storsol DOT com