Jon LaBadie wrote:
> The second part can only be done by actually doing restores.
> Perhaps you could schedule periodic recoveries of files
> or directory trees.  Do some sort of varying selection of
> clients, tapes, and data to recover.  Maybe even a regular
> "the chips are down" disaster exercise.


I would absolutely agree with Jon.

You simply cannot be "sure" or "guarantee," but you can attain a level
of confidence -- statistical sampling and testing if you want to get
formal about it. After installing a new backup system, the first thing
after backup should be to test recovery. Then, periodically pull a tape
at random and test recovery. Experience and confidence are common terms,
but you can also estimate probabilities of future success or failure
based on the data if you really want to dig into it.

The other side of this is your own personal experience and confidence.
When "the chips are down", you can say, "Ah, I've done that a bunch of
times. I'm confident I can do it now."

You need both of those in the common sense. If your bosses were to
really push you on the "sure" and "guarantee", you could go over to the
stat lab and ask someone to draw up some equations so you could hand
them back some probabilities. Could get messy if you try to account for
aging.


---------------

Chris Hoogendyk

-
   O__  ---- Systems Administrator
  c/ /'_ --- Biology & Geology Departments
 (*) \(*) -- 140 Morrill Science Center
~~~~~~~~~~ - University of Massachusetts, Amherst 

<hoogendyk AT bio.umass DOT edu>

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Erdös 4