[Zope-DB] Data.fs too huge

[rdl3 at compaqnet.fr]

Hi

I'm running zope 2.7.2 with CPS and haven't packed my database for about a year.

The problem is that it's now 25 GB (yes!) and I have to pack it, you
certainly understand why. But I've understood that when packing, zope
creates a backup file named data.fs.old, which is , logically, the size of
the previous database.
BUT the folder containing data.fs has only 5 GB space left, and there is no
other folder that could store such a big file on my server.

So my question is : 

is there a way to prevent zope from creating a data.fs.old when packing ?

Or, more generally : have some of you already had to deal with this problem ?

Thank you very much