Compression problems

[Ayman Altounji]

In doing backups with Arcserve on a Proliant, the tape appears to be maxed out at ~24gb. Hardware compression is on, software is off. I had the customer clean the drive, which was indicated. Tape b/u is set up to overwrite any existing jobs, so appending isn't an issue. Data is an assortment of small-business files, mail, proxy servers, and domain controller - - nothing unusual.

1. Is cleaning critical to compression?
2. Is 40gb just a theoretical maximum, with 60% of compressed capacity a normal real-world limit?
3. Is this just a tape drive hardware issue?

Thanks.