Re: [SLE] PROBLEM WITH TAPE HARDWARE COMPRESSION

On Fri, 2005-12-30 at 13:18 +0000, KRAMO FIACRE wrote:
> Hi!!!
> I've got an HP SURESTORE DAT 40 on my SUSE LINUX ENTERPRISE SERVER 8 BOX
> SP3.
> The tapes I use are marked 20/40GBYTE. But I can only make backup up to 20G,
> whereas on my ALPHA server with tru64 unix, I can save up to near 40 Gbytes
> using the dev file "/dev/rmt0h" (for tru64 V 4F) or "/dev/tape/tape0_d1"
> (for tru64 V 5.1B).
> I try to enable compression using the command "mt -f /dev/st0 datcompression
> 10", this command achieved succefully but nothing. I try to use the
> /dev/st0m or /dev/st0a, but these devices files seem not to be associated to
> physical device.
> So how can I perform backup with hardware compression?
> Please help
>
>
You may need to turn on compression after every reset of the tape drive.
Also remember that you will never get 40G of data on the 20G tape using
compression. Binary files never compress 50% and actually compress very
little and some even get larger when being compressed. Also I don't
recommend using software compression and hardware compression together.

Please fo not use all cap letters in the subject, it will not get you
any special attention in a response.

--
Ken Schneider
UNIX since 1989, linux since 1994, SuSE since 1998


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