DLT8000 size problem

                        Hi all,

I'm using Amanda 2.4.4 on RedHat 6.1.
After successfully installing Amanda, I have configure it following the
documentation.
My drive is a Quantum DLT 4000 but I use DLTtape IV of 40GB ( 80GB
compressed ).
So I have set the "tapetype" to DLT8000-40 getting from the FAQ-O-Matic.

define tapetype DLT8000-40 {
    comment "Quantum DLT8000-40"
    length 37482 mbytes
    filemark 2362 kbytes                # don't know a better value
    speed 5482 kps              # dito
}


After making a first dump of 32GB which must hold in my tape of 40GB,
I receive an error from Amanda indicating that my tape is to small 26 GB.
The log file says :

START driver date 20030405
DISK planner nestor.si.c-s.fr /data/projects
START planner date 20030405
INFO planner Adding new disk nestor.si.c-s.fr:/data/projects.
START taper datestamp 20030405 label cssi05 tape 0
FINISH planner date 20030405
STATS driver startup time 205.758

INFO taper tape cssi05 kb 26200288 fm 1 writing file: No space left ondevice

FAIL taper nestor.si.c-s.fr /data/projects 20030405 0 [out of tape]
ERROR taper no-tape [[writing file: No space left on device]]

FAIL dumper nestor.si.c-s.fr /data/projects 20030405 0 ["data write:Broken pipe

"]
  sendbackup: start [nestor.si.c-s.fr:/data/projects level 0]
  sendbackup: info BACKUP=/bin/gtar
  sendbackup: info RECOVER_CMD=/bin/gtar -f... -
  sendbackup: info end

FAIL driver nestor.si.c-s.fr /data/projects 20030405 0 [dump to tapefailed]

FINISH driver date 20030405 time 15115.619


Note : a "tar" archive was stored before using Amanda system.
Does Amanda not replace old datas when making a full dump ??
Do I need to erase datas before making a first dump ??

Regards

- Sylvain