About "incremental forever":

For the reasons discussed on this list, I have two onsite copies, and offsite
copies as well.  This gives me at least 4 backups depending on the cycle.
And, on a regular schedule do old style unix backups for the more important
systems.

I do this because we don't have the resources to do regular full backups.
ADSM helps a great deal in that respect.  The "incremental forever" saves
much in the way of resources. Problem is, you have to examine your
configuration in excruitiating detail and determine how many failures (big
and small) before you've lost data.  Failures can mean ANYTHING!

Big things like a 747 lands in your data center, a fire, a flood.
Incremental or full doesn't really matter in those situations.  Yeah, so
you've got 20 copies of something, but all of'em are on fire - maybe you can
sift throught the ashes later and get lucky.  And don't flame me about this,
because I'm hiding in the fireproof safe where the tapes were supposed to
be. Anyway, this would call
for use of offsite backups.

Little failures need to concern ADSMers.  The stuff like an operator drops
a tape, or it wears out, or the drive eats it.  Whenever this happens to a
storage pool you've just lost a cross-section of your data. (in that storage
pool)

The nice thing I've noticed about reclamation is that it reads your data
occasionally and you get the opportunity to find out about tapes that went
bad. It's found a couple for me already. I feel this helps offset problems
with "incremental forever".

Plus if somehow you manage all 4 copies manage to be lost, probably most of
the data would still be available, and reconstruction might be possible.

Finally, "incremental forever" allows us to backup more in less time. I think I
would feel more safe with full backups of every server every night, but....

Have a good weekend everyone!



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> Tim Dobrowolsky                   > <                yksloworboD miT <
> Computer Services                 > <              secivreS retupmoC <
> Catonsville Community College     > <  egelloC ytinummoC ellivsnotaC <
> tim AT catrs.cat.cc.md DOT us            > <         su.dm.cc.tac.srtac@mit <
> 410-455-4562                      > <                   2654-554-014 <
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