On Sat, 31 Dec 2005 09:14:36 +0100, "Rob Turk"
wrote:

"Paul Rubin" wrote in message
...
writes:
some advanced backup-solutions do allow to define the
"tapelifetime" in order to be able to use/take a new tape
from the tape-recycling pool before the tape in questions
really gets broken(e.g. too many read/write-errors).

Some drives let you read the error count registers but the commands
are drive specific.

The problem isn't so much to get the error counters (Log sense page 2 and 3
on almost all tape drives), but what conclusions to draw from them. If you
write 10GB to tape and the Total Corrected error counter is at 1000, is that
good or bad?? These are good for trend analysis when using known references,
but it's very hard to claim that a particular drive or tape is bad just
because it clocked a certain number of soft errors. Vendors will not provide
hard numbers of x % error rate as a cut-off point when you need to throw
the tape away.

Rob

If your tape drive supports the TapeAlert feature, then one of the
defined functions in the spec will report not only when the tape needs
to be replaced, but also when the tape is nearing end-of-life.

There are a few caveats, like having a tape drive that uses this
optional parameter in its implementation of TapeAlert, and having some
software (such as ours -- shameless plug that decodes and reports
it, but you can certainly write your own application.

To see if the TapeAlert mechanism an the media-related warnings are
impmlemented for your particular drive, then consult the
documentation.

David Lethe
http://www.santools.com