DLT8000 - Hp-UX10.20

[Managed Services]

Hi All

I have a customer who is using a dlt8000 40/80 -C6378A tape drive to back up data. The drive is supposed to have a 40Gb native capacity. The backup script works for the weekly backup which is around 17Gb but fails at the weekend backup of 25Gb. This seems a 20Gb threshold problem. The tape is a maxell IV 40gb which as far as I know has not previously been used in a dlt4000 (they haven't got one!). The drive is not set for compression at the moment.
The answer seems to be to set this... but I'm under the impression that the 40/80 is the uncompressed/compressed capacities.
Anybody any thoughts on this??

[Eugeny Brychkov]

Hi MS,
please use HP LTT http://www.hp.com/cposupport/information_storage/support_doc/lpg50128.html to generate support ticket for the drive (file with .ltt extension) with this tape inserted, zip it and attach to your next reply.
You can try running different tests using this utility: perfomance, compression, etc
Eugeny

[David Holbrook]

The Maxell IV 40GB tape is rated to give 20/40 in a DLT4000, but should give 40/80 in a DLT 8000 (native/compressed mode). I am confused as to which you actually have, as you mention both. You will have to turn on compression to get the higer figure, but in real practice you can only expect to get somewhere at about 1.5:1 compression, depending on the data being written. Another thing to look out for, is the data on the drive stored as compressed files? If so, the data will expand back to full size as you back it up, so the thing to do is to look at the log files and see how the data on the tape actually compares to the sizes on the drive.