I'm having problems getting backups working on SCO OpenServer 5.7.

using the following command:

find / -depth -print | cpio -ocvB -O /dev/rct0

some files are backed up then the following error is reported:

Reached end of medium on output.
Device /dev/rct0: Change to part 2 and press RETURN key. [q] q

The tape device is DDS4 (20Gb) and there is only 3Gb of data on the machine so there should be plenty of room on a single tape.

I've tried a different tape drive with the same issue so I don't think it's a hardware problem.

Any help would be appreciated.