Can I put more than one backup on DDS with fbackup?
No. fbackup always rewinds the tape. Possible alternatives: (1) Stick with dump/cpio/tar/pax. (2) Use a pipe: instead of telling fbackup where the DAT is, let it send its output to stdout (-f -) and pipe it to the DAT, using Berkeley no-rewind device and dd with a suitable block size (e.g., 10K). You’ll lose fast-search and resync-after-error functionality, though. Also, the complexities of managing multiple archives per tape make this a high-risk proposition. (3) Use NFS[R] and mount the disks of the machine without DAT to the other and back them both up there. You’ll have to mount ’em with root permissions and restoring a completely destroyed root disk will be messy. (4) Scream at HP until they fix fbackup.