> In regard to: Re: [Networker] how to keep exactly 2*N days of backups at...:
> 
> > Sounds like your bosses want the mail spool to be purged every 14
> > days.  In that case, why do backups at all?  Just put the storage on a
> > NetApp and setup N*2 nightly snapshots.  They'll get deleted
> > automatically and you won't have to hassle with tapes.
> 
> You have correctly guessed why they've asked for exactly X number of days.
> We already have a significant SAN infrastructure and our mail spools are
> distributed over multiple hosts, so I don't think adding a NetApp device
> to the mix is going to be an option (no matter how perfectly it would
> accomplish what they're looking for).

More to the point then, you may need to have 2*N volumes.  You can't
erase data from the beginning of a tape.  You can only mark it expired.
Recovery from a 'recyclable' tape is pretty easy.  It's only after the
volume is relabled that it's difficult.

As an in-between measure, you could also delete the media index for the
older backups.  Then the data is still on the tape, but it becomes more
difficult to quickly restore.  (You'd need to either scan the tapes or
recover an older bootstrap)

> I have confirmed with management that keeping 2 weeks + the weekly full
> that the oldest differential depends on will be satisfactory, so I'll
> proceed with that plan.

Ah, cool.  Never mind then.  Of course you may still want to consider
what exactly happens the day the full expires.  It may continue to be
easily recoverable for months, depending on your tape rotation scheme.

-- 
Darren Dunham                                           ddunham AT taos DOT com
Senior Technical Consultant         TAOS            http://www.taos.com/
Got some Dr Pepper?                           San Francisco, CA bay area
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