I have an external HP DDS-3 Device hanging off my Redhat 7.2 Box. I've spent a considerable amount of time developing an in-house backup system (script) because I refuse to use a proprietary package. Plus, this makes it easier to move files from one system to another.

Anyway, I using the st device drivers and the mt command to backup files. I'm able to do full backups using the automatic rewind device (/dev/stape/tape-rewind) but I'm having a hell of a time trying to append incrementals. Utilizing the following command...

# cat /tmp/files.tmp | cpio -oc | gzip -c > /dev/stape/tape-rewind

...I'm able to backup all files listed in the .tmp file, and restore them. cpio shoots back a response to stdout, indicating the number of blocks stored ####.

The problem is, cpio only reads one block on append. What could I do, hopefully keeping the current schema of commands, that would allow me to save incremental backups?

Use non rewind tape device to create incremental backups.

Usually defined as:
/dev/st0 is rewind
/dev/nst0 is non-rewind.

When using /dev/nst0, I get the error explained above. CPIO reports 1 block saved. I have been playing around since my first post, and I've come up with something very peculiar. Upon checking the status, I get this from stdout...

SCSI 2 tape device:
File number=0, block number=0, partition=0.
Tape block size 0 bytes. Density code 0x25 (DDS-3).
Soft error count since last status=0
General status bits on (41010000):
BOT ONLINE IM_REP_EN

This is after I have backed up files using nst0.

I tested your command on my system and it writes to tape. I have a DLT 4000 tape drive. I would except it save more than one block.

You can test writing to the tape drive by using the dd command too.