Dear TSM Community,

I have a situation in which I appear to have lost hardware compression on
both my 3570-C drives. We recently had one of two tape drives in a 3575
replaced, and since then I'm only getting 5 GB a tape, in spite of my
device class being set to format=drive (not that I have changed this). I do
not compress at the client.

Here are the headlines;
TSM Client is at 4.1.3.0
TSM Server is at 4.1.4.1
The drives are enabled for hardware compression (lsattr -El rmt0 shows
"Hardware enabled for compression: TRUE")
Atape.driver has been updated to 6.1.9
The 3570 Firmware has been updated to 5468
I have green 3570 tapes.
I have deleted the drives in TSM, deleted the devices in aix, recreated the
devices, redefined the drives.
Backing up approx 1GB with dsmc sel and no software compression utilises
20% of a tape.
Backing up approx 1 GB with dsmc sel and software compression (reporting
50% compression) utilises 10% of a tape. So I know the data is
compressable.
The devclass has a setting of FORMAT=DRIVE. I've tried making a new device
class with a new tape storage pool and backing up to that with TSM but
there's no relief - I'm still only getting 5 GB per tape for data which has
NOT been compressed by the client.
I've just used tar to back up 12 GB of data successfully to one of the
drives - so it looks like TSM is the problem.

Any ideas? As a consequence of this problem my scratch tapes have rapidly
been consumed and I could do with a brilliant suggestion.

Thanks in advance.

Eric Winters