On Wed, 26 Mar 2008 15:02:22 +0000, Orchid XP v7 wrote:

>>> We do. On every backup run. And to this day, I have never, ever had a
>>> problem restoring something that the backup software said was OK.
>> 
>> Do you do a checksum-based verification, or a compare-to-disk
>> verification?
> 
> It should be a compare-to-disk verification. (At least, it generates
> enough I/O traffic!) I would think anything less wouldn't tell you
> much...

I can certainly tell you it doesn't.  The only way to test the 
readability of a tape effectively is to actually read it and compare the 
data to disk.

>>> Indeed, if the tape is wearing out, I usually get an error message
>>> before the verify phase even begins. (Not sure how it manages that,
>>> but it often reports a CRC error...)
>> 
>> I imagine that even without a verify, your software checks during the
>> backup process to make sure it was written properly.
> 
> Yeah, but I was thinking at the physical level. Maybe it's a 3-head tape
> system?

Could be.

Jim

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