Topic: Tape drive compression

[Trevor Drake-Brockman]

Can anyone tell me if Flexbackup uses tape compression.  I have a 4/8GB IDE tape drive and but flexbackup stops at just below or just over the 4GB boundry.  So it looks as if no compression is used however in log of the backup if suggests that it uses gzip -4 any idea on how to set the tape compression on.

So by the way the log is reporting 'no space left on device'

[Filippo Carletti]

First problem:
how to enable tape (hardware) compression on ide tapes.
I didn't find the answer.
flexbackup could be modified to use soft compression, but how ?

[Michael Doerner]

Same thing here with 2 different SCSI tape drives - hardware compression is not working (can't enable?).
These drives are
- Tandberg SLR5 (4/8 GB),
- 4mm DAT drive (HP?) with also 4/8 GB.

Flexbackup fails on both servers just after 4+ GB.

[Filippo Carletti]

Have you tried mt compression ? (see mt man page)

[Michael Doerner]

Hi Filippo,

I thought I had tried all mt parameters before without success but your question made me trying again (I have only remote access to the server with the DAT drive) ... and it looks like it's working!
My last tries I did with an older SME/kernel/mt(?) version which might have been differently?

It's still a bit strange because
- defcompression apparently doesn't do/change anything (?) but
- compression 1 or datcompression on seems to make the change (at least for that device).
I will have to watch for the next days what happens from here, also I don't know whether this datcompression on setting will be kept over a server restart (then I would have to add it somewhere to server startup procedure)  but I am happy to have some progress.

Thanks for your input.

Kind Regards,
Michael Doerner

[Filippo Carletti]

compression settings will probably be lost across reboots.
flexbackup would be a suitable place to make them permanent.
Also, I couldn't test it, but I believe that datcompression could not work.
I didn't check if mt-st was upgraded in sme5.