ADSM-L

novell/aix backups

1996-03-20 09:41:21
Subject: novell/aix backups
From: "Andrew M. Raibeck" <araibeck AT VNET.IBM DOT COM>
Date: Wed, 20 Mar 1996 06:41:21 PST
Barb Lundberg asks:

>Our shop is running ADSM V2R1 on AIX 4.1.4.  Much of what we will be backing
>up are Novell and AIX servers.  My question is whether or not we should
>periodically run a full backup of these servers (mode=absolute).  My fear is
>that if we do only incremental backups that 6 months to 1 year down the road
>if we need to restore the server it will require many many tape mounts which
>could take a substantial amount of time.  cComments?

The problem many, if not most shops face is finding the time to take full
backups, as the window just isn't there. ADSM isn't really designed for the
"traditional" LAN backup strategy of a periodic full followed by daily
incrementals, although you could probably develop a strategy for doing so.
In fact, as a former customer, I considered the lack of a need for full
backups to be an advantage.

With ADSM, you really don't have to take periodic full backups. Yes, you can
get into the situation you describe, with many tape mounts being required to
restore the server. However, there is a feature called "collocation" that can
be used mitigate this issue. With collocation, ADSM can keep each ADSM client's
data on it's own set of tapes. That is, data belonging to client A can be kept
separate from data belonging to client B. Reclamation will help ensure that
tape capacity is utilized more efficiently so that the number of tapes each
client occupies is minimized.

The cost (there's always a cost :-) ) is that you will incur more tape mount
overhead in maintaining collocation. To put it simply, it's a trade-off.
Collocation optimizes restores, with the "hit" being taken on the backup side
of the house. Non-collocation optimizes backup, with the hit being taken on
the restore side. You also take a "hit" in doing the periodic full backups.

Andy Raibeck
ADSM Level 2
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