Hello list,
I have a problem understanding the coherence between tape_splitsize
and runtapes.

The Config:

on my current system, i backup 2 disks with about 2 and 3 GB on
DVD-RAM (like a virtual tape on hdd)
It works fine, because the folders are smaller than 4.3 GB.

Now i want to backup one folder with 5 GB and decided to test the
tape_splitsize option.

I set up a VM for testing: (Test Environment With Virtual Tapes)
http://wiki.zmanda.com/index.php/Test_environment_with_virtual_tapes

org "Acme Inc."
mailto "root@localhost"
dumpcycle 3
runspercycle 3
tapecycle 5
runtapes 1
dumpuser "amandabackup"
tpchanger "chg-disk"                            # a virtual tape changer
tapedev "file:/space/vtapes/test/slots"
changerfile "/var/lib/amanda/test/changerfile"
labelstr "TEST-.*"
#label_new_tapes "TEST-%%"
tapetype DVD_SIZED_DISK
logdir "/var/lib/amanda/test"
infofile "/var/lib/amanda/test/curinfo"
indexdir "/var/lib/amanda/test/index"
tapelist "/var/lib/amanda/test/tapelist"

holdingdisk hd1 {
   directory "/space/amandahold/test"
   chunksize 10 Mb
}

define dumptype comp-tar {
   program "GNUTAR"
   compress none
   index yes
   split_diskbuffer "/space/amandahold/split"
  tape_splitsize  10 Mbytes
  fallback_splitsize 10 Mbytes
record no           # Important! avoid interfering with production runs
}

define tapetype DVD_SIZED_DISK {
   filemark 4 KB
   length 30 MB

}

I backup /etc in this example:
du -sh /etc/
48M     /etc/

My virtual "DVD-Drive" have only 30 MB.

Now the problem:
if i try amdump test with runtapes = 1 the following error appears :

FAILURE AND STRANGE DUMP SUMMARY:
 server  /etc  lev 0  FAILED [dump larger than available tape space,
38620 KB, but cannot incremental dump new disk]
 planner: FATAL cannot fit anything on tape, bailing out

if i use runtapes = 2 it works.

I can only write on DVD at once.
Can I use tape_splitsize in this scenario or shuld i backup the 5 GB
folder in 2 pieces?

I hope you can help me
Sebastian