I am using Amanda for year as primary backup tool for my Linux/Unix pool.

Some months I introduced an Exabyte VXA drive and VXA-V23 (80GB uncompressed) 
tapes to cope with the ever expanding storage.
I backup 25 DLE's of varying size 18 MB to 55 GB. Amanda nor the hardware 
compress the data.
TapeType definition sets the Tapesize to 75 GB to add some slack in the system.
Backup program is gtar.

Recently I get the following error when the large DLE's are backup up

*** A TAPE ERROR OCCURRED: [[writing file: No space left on device]]. 
Some dumps may have been left in the holding disk. Run amflush to flush them to 
tape. 
The next tape Amanda expects to use is:

The mail message indicates that only 65 GB has actually been written at the 
time the tape ran out.
 taper: tape xxxxxx kb 65110688 fm 25 writing file: No space left on device

Some incremental backups (9 in total) are very small 60 KB to 5 MB. 
Can this be the cause of the gross miscalculation of the tapelength?? 
What is the minimum tape length for a DLE backup ??

Thanks
======================================================
Gerrit Hommersom                        Dow Benelux BV
tel:    -31-115-674102                   E&PS/439 Bldg
fax:    -31-115-673315                       PO Box 48
E-mail: ghommersom AT dow DOT com           4530 AA Terneuzen