Why do cpio/tar/dump/pax all backup to tape painfully
cpio/tar = VERY VERY OLD - never designed for DDS or DLT[TM]
fbackup/ftio = designed for Gb backups and modern tape drives
However, the default for fbackup is 1/2" magtapes, which almost no one
uses anymore. ALWAYS use a config file for fbackup with at least these
Check the manpage for fbackup for other parameters, including what to do
when you run out of tape (the chgvol parameter).
You need huge block sizes for modern tapes. Try ftio (block size limited
only by hardware), pax (block sizes up to 32k), tar (which is 10k, by
design) or cpio -B which changes from 512 to 5k (but still too small).
cpio, tar, dump, pax and similar utils can NEVER backup large files and
are single processes whereas fbackup can read from 6 different files at
the same time.
Note, the large record size (blocksperrecord), checkpointfreq, and
filesperfsm also contribute to tape overhead.