WebSphere Portal can eat your disk space

When you have a portal for a long time (My case since you apply a list of Fix during the life of your portal.
The directory version grows and you need to clean up to free disk space,

I open a PMR and the answer was:

"It is critical that the client does not remove the jar files from the   
backup folder.  This folder is very important if you decide to uninstall
a fix/fixpack or upgrade to a new fixpack.  If you install a fix, say   
PM0001 and it affects the portal.jar file.  What happens is that the    
original portal.jar file is stored in the backup folder and the new     
portal.jar is deployed.                                                 
So if we have a scenario where the client wants to upgrade to the latest
fixpack and their current Portal has several fixes applied.. when you go
to upgrade, part of the install process is to uninstall those fixes     
(thus those jar files that each fix affects are removed and replaced    
with the associated backed-up jar files in the backup folder).  You will
break Portal and it will be very painful to recover.                    
The logs folder can be emptied."