Space on DLT ?

[Javier Juarez]

If a DLT with a capacity of 40GB/ 80GB (compressed) Omniback reports only 20GB cap, and I made a backup with compression,i.e. 14GB, The GUI shows only 6 GB Avail. why I cannot see true figures?, I expect see 80-14 = 66 GB Avail.

Ane Idea?

[Steve Sauve]

Is HW compression on? Also what type of DLT tape and drive is it?

Steve

[Patrick Wallek]

It sounds like Omniback thinks your drive is a DLT4000 rather than a DLT8000. You might check and see if there is a way to tell Omniback what type of tape drive your have.

[Peter Brimacombe]

From my experience with DAT tapes, the precise total capacity of a tape is unknown, the first unknown is the degree of compression possible. Further I suspect that the media agent streams the tape at a constant rate, if the disk agents can't keep up then the tape keeps streaming but no data is written.

[MARREEL Chris_1]

When you "format" a DLT-tape the default size is 20Gb. You should set it manualy to e.g. 80Gb if you use Hardware Compression.
This is only a parameter Omniback uses to estimate how much place there is still on the tape. Everything depends on the 'type' of data.
If you let Omniback to "auto-format" he will set the size to 20Gb, I don't know how to change this auto-value.
I should say always pre-format your tapes if you want to use the 'estimation' of the free space still on the tape.

Hope this explains...

[Ken Scharpell]

Omniback does a poor job of trying to determine hte size of a DLT tape. Dont use the DETERMINE option when initializing the media, use the SPECIFY option and set it to what you know the capacity is -eg. 80GB for an 8000.

[Andreas Voss]

Hi,

here's the procedure to change the init capacity:
Edit /etc/opt/omni/options/global:
Add the line:
MC_10=1 36 250 81920000 4
This will change to 36 months AgeLimit, 250 overwrite limit, 80GB capacity, 4 concurrency for DLT devices

Regards