DAT 40i - Compression failure

[Patrik Jonsson]

Hi everyone!
I have two DAT40i drives i my computer (NT4.0)
and everything worked fine until i discovered that none of the drives passes HTT's compression test. The test states that compression i currently DIABLED! And the test fails upon enabling compression. My backups fails because of the amount of data beeing backuped. Help is wanted.

TIA

//Patrik

[Adrian Rockall]

We also have the same problem. The DDS4 tapes appear to hold the same amount of data (25GB)as our old DDS3's. We sent our first DAT 40 back because we thought it was faulty but he replacement drive is the same. When we run the test software it tells us that compression is disable by the switch underneath and fails if ask it to compress anyway.

[Adrian Rockall]

Having spent some more time trying different things I found the by moving all the switches back and forth so they end up back in the default positions has sort of fixed the problem. The test software no longer reports the switches are set incorrectly and the drive achieves 2.53:1 compression during the test. Maybe there is flux or something effecting the switches during production (just a guess).
However, during a backup of our normal data we still only get the same amount of data on our DDS4 tapes as we did on our old system with DDS3 tapes! We use exactly the same settings in NT backup for both systems so we would expect all our data to fit on one tape instead of one and a bit tapes (we backup around 28GBytes).
Also the test software reports after a normal backup a compression ratio of 1.-118:1. The "-" is not a typo on my part but actually appears in the report.
Any one got any suggestions?