Amanda and rait: mirror backup setup

[die...@gmail.com]

I setup a mirror backup with rait using the instructions in this link:
http://wiki.zmanda.org/index.php/Rait.

The works fine but the problem is when the tape fills up. Instead of
request a new tape the amdump fails with "no left space on device
error".

I have one LTO-3 (400 GB) unit and i trying to backup 600 GB without
compression for testing purposes.

What other alternatives i have? what about a combanation of chg-rait,
chg-manual and chg-multi? The documentation about chg-rait is not good
:(.