Cleaning Drives Which are filled for disk backups

[RBoyle]

I have 2 - 2.6 TB LUNs that are configured for disk backups for Legato
Networker Version 7.2.2 Build 422

These two LUNs are completely full and when my jobs that are
attempting to save to disk run they take forever because they clean
off the disk in such a slow fashion and then back up the nightly
backup to disk (and then do it over and over again for each client i
have this set up for).

Is there any way that I could clear out some of the backup data that
is located on my two LUNs, and if so how can I locate what is what
within those directories.

From just glancing at it it looks as if there is apprx 30 directories
on each LUN randomly numbered via the Legato software as an index.

I want to free up some of the drive space however I do not want to
damage my backup jobs and / or the software and how it runs on a
nightly basis. If anyone can give me tips I would greatly appriciate
it.

** in advance -- I have no more space to create a third disk for disk
backups, as my SAN is full.

Thanks in advance for the assistance.

Ryan