On Wed, Mar 09, 2005 at 07:39:13PM +1100, Jobst Schmalenbach wrote:
> 
> All,
> 
> I have tried to search the docs and faq for this but 
> couldnt find any info.

Probably looking for it under a specific name.

> 
> I want to use two sets off tapes so I can have one 
> on-site and one off-site and swap those every second
> week or so.

But this is more a general operating principle.
> 
> 
> How do I do this? 
> Do I use two different Sets, eg. DailySet1 and DailySet2?
> 
> Do I make two daily sets with 10 tapes each, so I
> can backup 5 times (workdays) a weeks for 2 weeks
> and then swap the sets?
> 
> 
> Do I name the two tape sets with the same labels
> and then just swap them over?
> 

It sounds to me as if you have a dumpcycle set for about
one week, with 5 runs of amdump per dumpcycle.

Further, it appears you 'feel' that for such a setup
you will need 5 tapes, one for each run of amdump.

That is where your setup is out of kilter.  The norm
is to have in rotation, 2, 3, 4, or more times as
many tapes as are needed in a single dumpcycle.
Then it is simply a matter of taking offsite a group
of 5 tapes from the normal rotation and exchanging them
a week later.

If budget permits 4 sets of tapes (is your data worth it?)
you could have a set in use plus, on-site the most recent
set for recovery of recently changed things, off-site the
set from 2 weeks ago, and on-site the set from three weeks
ago that will be re-used and overwritten next week.

All those would be from the same config, just numbered or
named something like xxx01 - xxx20.

Don't get hung up over the tape names.  Specifically, don't
call them something like "set1-1, set1-2, ... set4-1", or
Monday-set1, Friday-set4, ...  Invariably they will get out
of sequence and the names will be more confusing if you assign
them set membership rather than simple identifiers.  Who really
cares if the box labeled set 3 contains tapes 11, 12, 14, 15, 16 
(tape 13 somehow slipped to set 4 :) rather than set3-1 to set3-5.
But if tape set3-3 slipped into set 4, then people would be upset.

-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
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