Why don't you split your disk among several directories (aka DLE,
disklist entry). I guess that's common practice in amanda, and indeed
a powerful mechanism. I'm using 36GB tapes for a pool of several
hundred GB across a server farm. I split the pool into a bunch of DLE,
dividing among filesystems and directories, in a reasonable
fashion. I'm using about 35 DLE's; the backup is split among several
tapes along the dumpcycle. It all works fine. For instance, if you
have a /home with lots of users, you can even split alphabetically by
first letter, say, [a-d] for one DLE, [e-h] for another, and so
on. Moreover, since each DLE is smaller, it is fast to recover a
specific file or directory, since the tape can fast forward to the
dumped DLE in question.

Cheers,

Rodrigo

-- 

*** Rodrigo Martins de Matos Ventura <yoda AT isr.ist.utl DOT pt>
***  Web page: http://www.isr.ist.utl.pt/~yoda
***   Teaching Assistant and PhD Student at ISR:
***    Instituto de Sistemas e Robotica, Polo de Lisboa
***     Instituto Superior Tecnico, Lisboa, PORTUGAL
*** PGP fingerprint = 0119 AD13 9EEE 264A 3F10  31D3 89B3 C6C4 60C6 4585