stsadm backup & diskspace - Sharepoint

Hi,

I have created a small backup script to create a full backup of our
MOSS 2007 SharePoint farm (with SP1) (on a remote share. This has been
running very well, up until very recently. I am now confronted with
the following message:

There is not enough disk space. Free additional space on your hard
disk and then
try again. Approximate amount of space needed: 35.41 GB. Amount of
space free o
n disk: 32.94 GB.

The computation in the above message is correct, however, when I
temporarily free up some diskspace, the total amount of space needed
for the backup is just over 17GB, which would fit easily on the drive.

My guess is that stsadm does a rough calculation of the database sizes
(datafiles and transaction logs), and compares that to the available
diskspace, while the actual backup of the databases is written to disk
either compressed or without the full transaction logs (only the
available transactions in the logs added to the backup).

I can understand it if it works this way, but I would like to know if
there is any way to force the backup to continue.

With kind regards,

LF