On Tue, May 08, 2007 at 10:10:15AM -0400, Chris Hoogendyk wrote:
> 
> 
> 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.
> 

One thing I dislike about "random" sampling is the possibility of never
testing certain combinations.  I think the statistical approach would
give me more confidence, particularly if all combinations were regularly
tested in a reasonable time frame.  Of course your reasonable time frame
might seem excessive to me ;)

> 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.

The confidence and experience aspect is a great point.  And if your
backup system is worth 12K as was stated, then there are probably
multiple people who need to gain that experience and confidence.
Not just the one with primary backup responsibility who invariably
happens to be on vacation just when "the chips are down".

-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
 4455 Province Line Road        (609) 252-0159
 Princeton, NJ  08540-4322      (609) 683-7220 (fax)