DDS Tapes lifetime

I Replace them Annually...

The only thing I've found was on one of the tape vendor sites. They stated that their DDS3 product was good for several hundred passes, but that for safety sake should be scheduled for replacement after 100 backups or restores.

Cleaning tapes typically have a relatively short lifespan, check the documentation that came with the tape, generally good for 20 - 30 uses.

Real world, we've got eight tapes used in rotation on one server that have been in use five days a week for five years without reported problems.