Hi all,

In devices.txt;

9 char SCSI tape devices
0 = /dev/st0 First SCSI tape, mode 0
1 = /dev/st1 Second SCSI tape, mode 0
...
32 = /dev/st0l First SCSI tape, mode 1
33 = /dev/st1l Second SCSI tape, mode 1
...
64 = /dev/st0m First SCSI tape, mode 2
65 = /dev/st1m Second SCSI tape, mode 2
...
96 = /dev/st0a First SCSI tape, mode 3
97 = /dev/st1a Second SCSI tape, mode 3
...
128 = /dev/nst0 First SCSI tape, mode 0, no rewind
129 = /dev/nst1 Second SCSI tape, mode 0, no rewind
...
160 = /dev/nst0l First SCSI tape, mode 1, no rewind
161 = /dev/nst1l Second SCSI tape, mode 1, no rewind
...
192 = /dev/nst0m First SCSI tape, mode 2, no rewind
193 = /dev/nst1m Second SCSI tape, mode 2, no rewind

In above device descriptions, what does it mean by "mode" ?
What are "mode 0", "mode 1", "mode 2" ?

Among above devices what is the tape with compress enabled ?

Thanks in advance.

-San

I've used /dev/st0 as the tapedevice and to control it I used a combination
of mt (the tapedrive) and mtx (the changer as a device /dev/sg3 )

the compression I handled with the z flag (of the j of y for bzip2)

tar zcf /dev/st0
tar zxf /dev/st0

The advantage: it works very easy, but I can imagine that the correct
/dev/ device might be more compatible with other solutions and maybe
there exists even some compression in hardware.

The mt and mtx commands have a man page that explains the usage, but
what I never discoverd is the correct way to handle the changer.

Tlowk

About the compressing tape drive.

What I actually want to do is to export a database directly to the tape instead of writing to the disk and then writing to the tape.

I can not tell to compress while exporting.

that's why I want to write to the compressing tape.

-San

I don't know enough about it, but what you can try as a work arount

backup to:
"| gzip -c > /someDit/somFile"

or:

another way (just a wild guess to be honest)

mkfifo /somedir/compess
cat /somedir/compress | gzip -c /dev/st0

and make the backup to /somedir/compress