amanda-server, as shipped with PowerTools 6.0 (PowerTools 6.0 isn't yet defined in bugzilla?) fails to backup, as it incorrectly reports the available holding disk space to be 0KB (even when there's several gigabytes free diskspace). This is due to the new glibc2.1 libs in RH6.0. A patch can be found on http://www.egroups.com/group/amanda-hackers/1181.html
Fixed in next release. Tim