Quantum states 1,000,000 passes for SDLT and DLT IV, and 500,000 for DLT 
III

http://www.quantum.com/Products/DLTtape+Drives+and+Media/Tape+Media/Default.htm

click on Super "DLTtape Media Data Sheet" and "Super DLTtape Media Data
Sheet" on the right, under Tape Media Marketing and News.

This is of course, not uses, or mounts, but I will not be throwing away
SDLT tapes here after only 100 mounts.  OTOH, our daily tapes, which each
are used once per week, will see only 150 mounts.  This is assuming a
three year technology refresh cycle.  The weekly tapes, used once per
quarter, should last much longer than we require.

I have heard no recommendations from anywhere else.  Feel free to let me 
know if I'm way off base.

Ron.

On Wed, 17 Jul 2002, Fabbro, Andrew P wrote:

> Max mount of 50,000 for DLT?!? 
> <clutches his chest>  Oh, 'lizabeth, this is the big one!  Oh!
>  
> The suggestion I've heard time and again is 100 max mounts, based on
> "full-length writes".  I've used 125 (assuming that some of my writes
> are not full-length) for DLT-7000 and was feeling racy.  Even some of
> the newer hardcore, macho-enterprise-man stuff (e.g., STK 9940) is not
> rated for 50,000 mounts.
>  
> I've long suspected that the suggestion of 100 mounts was way on the
> conservative side.  But the value of the data is usually infinite
> compared to the cost of the media, and I don't want to be the one who
> says "yeah, I saved us fifty bucks on buying tapes but I lost your
> database, mister vice president".