Item Subject: cc:Mail Text
Following is a response to my DDS "head (mis)alignment" queries.
This is from Dantz Development Corporation < http://www.dantz.com/ > ,
makers of the Retrospect family of backup software.

Interestingly, they don't seem to have encountered the problem
very often.  My guess is that either (1) they don't have many customers
that use DDS as the backup medium, or (2) few customers have needed to
restore either from an older tape or from a different drive.

<plug>
Incidentally, Retrospect is the product that PC Week opined in July 1997
was "so easy to use and feature-laden that mixed-system network
administrators will want a Macintosh just to run the $249 program."
</plug>

FWIW.

--Glenn Cole
  Software al dente, Inc.
  [log in to unmask]


We've had a handful of customers who had encountered "Content Unrecognized"
(CU) when trying to restore from older tapes, but not from newer tapes.
After the drive was replaced, the older tapes read back fine, but the ones
that had been created in the last 2 months were "Content Unrecognized". So
that does point to head alignment creep.

However, most "Content Unrecognized" errors happened on just one or a few
bad tapes, and were (Presumably) media errors on the header or device area
of the tapes.

So my troubleshooting technique always focused on determining how many
tapes were affected by CU, and their age.

If all older tapes --> likely bad drive
If only a few tapes --> likely bad tapes

And of course, the lead cause of CU is trying to read a compressed tape on
a drive without hw compression.