Do not forget about DB backup sent off-site.
Most probably you are moving them but did not mentioned. The reusedelay and
DB backup retension should set that only after a DB backup with information
about the new volume where data is copied as result of copy pool
reclamation the old reclaimed tape can become "empty" and be brought
on-site.

Zlatko Krastev
IT Consultant





Justin Derrick <jderrick AT CANADA DOT COM> on 24.01.2002 15:05:30
Please respond to "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
To:     ADSM-L AT VM.MARIST DOT EDU
cc:

Subject:        Mitigating Risk with TSM's incremental backups

I've been using TSM for quite a few years on AIX, and surprisingly, this
issue hasn't come up before.

My customer is using TSM in conjunction with Content Manager OnDemand.  The
config looks like this:

AIX 4.3.3 on H70
OnDemand, DB2, TSM
Data is cached on disk (by OnDemand, not TSM), and also copied to Optical
(a la 3995), then backed up to LTO.
They are currently a very low-volume shop, adding under 1GB a day to the
TSM system.

The question raised to which I didn't have a good answer was:

If we take a non-full LTO offsite for disaster recovery purposes, then
bring it back onsite as part of regular rotation, a vulnerability is
created.  If the tape is on site when a disaster occurs (which would always
be the case since their courier only delivers once a day), not only is that
day's information lost, but all the previous days of incrementals
previously written to the tape are destroyed as well.

I know we could keep multiple copypools in the chain, but it seems like an
expensive solution to a simple problem.

The immediate solution would be to create new 'full' backups of the
contents of the optical jukebox every day, and take them offsite.  While
this would actually be feasible in the short term (given their low growth)
it would quickly become unmanagible in the future.

Is the solution to simply buy enough tapes so that you simply send one tape
a day offsite for as long as possible, then perform large reclaimation once
every 'long as possible'?  This sounds like it's within the realm of the
DRM, which I'm woefully inexperienced with.  Any advice, direction, etc.
would be greatly appreciated.

-JD.
=========================================================================