On Tue, Aug 08, 2006 at 09:22:20PM +0100, Alan Pearson wrote:
> 
> 
> Guys,
> 
> On this subject, I'd like to do something similar. Unfortunately my  
> backups don't fit on one tape !
> How can I take a _complete_ backup off site in this situation, and  
> how can I identify which tapes I need to take ?

I'd recommend a separate config of no-record, full dumps only.

But assuming you can't, the answer is complicated.

Nominally you need any dumpcycle's set of tapes.  It doesn't matter
which day you start, any sequence of a dumpcycle's number of tapes
should contain a level 0 of each DLE from someday within that cycle.

How many tapes are in a dumpcycle?  Well, the max should be
runtapes X runspercycle.  But if runtapes is > 1 and the same
number of tape is not used each day, how many were used in the
dumpcycle you are collecting?

Furthermore, there can be multiple dumpcycles and runspercycles in
a single config.  These parameters can now be set differently in
different dumptypes.  So which do you use in collecting your tapes?

Another "potential" problem to look out for is DLEs that should
have had their level 0 on the last tape you select but due to some
error (eg. system down or tape problems leaving some things on
holding disk for taping next run), you might not have a level 0
of each DLE on the tapes you select.

I don't know of any tool that would let you do something like:
"given a date (or a tape), determine the minimal collection
of tapes, going forward or backward, that contain at least one
level 0 (successful dump and taping) of each DLE".

Could be a useful tool.

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