Many fragments on DP 6.11

Hi,

I use DP 6.11 to do D2D backup and D2D2T backups.
Also I use D2T for many Backups.

I have a problem of retention for D2D backups...
DP write fragment on my SAN. Lots of fragments. But after 3 ou 4 days, my Lun is full and D2D backups failled because "Not enought space".
These backups are write to tape every days.

How can I clean manually fragments which are send to cartidges ?

I know there are a lots of command like omni... (omnistat/omniabort...)
One of there can solve my problem? Since 3 weeks there are no backup on my compagny...

Thanks

omnidbutil -purge -filenames -force is it the solution to clean obsolete fragments and preserve fragments not save on cartidges?