This one time, at band camp, Gene Heskett wrote:
>>If you have plenty of holdingdisk space, I would think they would go
>> there. Even with the default reserve of 100%, you should still get
>> the incremental. You might have to look in the debug files to see
>> why they were completely skipped.
>>
>If the dumps are too big, and the holding disks reserve is at the 
>default of 100%, the dump *will not be done*.
>
>Set the reserve on the holding disk, if you've got a ton, to something 
>like 30%, which will let it do fulls till there is only 30% of the 
>holding disk left.

The reserve is set to 40%.  Amanda is not dumping anything once the planner
decides it won't fit on the tape, according to the debug log.