How many bad tapes are "normal"? [closed]

I use Quantum DLT-S4 tapes (800/1600GB) in my library, which has two Quantum tape heads in it. I have had quite a few bad tapes i.e. tapes that come up "CRC error" or "cannot read tape" etc and the backup software marks them as bad. I've sent back around 20 to Quantum out of 100 for a refund. The library is only 18 months old, and one of the drives has already been replaced a while back. Still get bad tapes. How many bad tapes do you guys get?

Solution 1:

About a year ago I switched the system at my office to a rotating pool of about 80 LTO4 tapes and have only had one tape fail - it was physically dropped though. The rest of the tapes go through backup/restore/verify cycles and have never had an error.

Prior to that we used over 200 LTO2 tapes and had only a single error in the two years I was with the company (the tape errored out while writing to it). For what it's worth both the LTO2 and LTO4 drives are Sun-branded HP Ultriums inside a Storedge L8 and an SL24.

So I'd say 20 out of 100 in my experience at least is ridiculously high, so much that I would be extremely wary of trusting that system to handle a company's backups.

Solution 2:

I would expect that answer to be 0, assuming that the tape was used within the limits of rewrites, temperature, storage, etc.

I would start looking at the environment that the drive operates in, or the tapes are stored in.