Make sure you have a fresh or recent backup of NVDB.
1) Delete the contents of ..\nv\db\pgsql\pg_log
2) Aggressively compress backup indexes on disk: As backup are performed, each client sends the backup index to the NVDB which is stored under the nv/db/MediaDatabase folder as binary file and containing the list of items backed up by each job and allowing us to see the saveset contents and restore from it.
The more we backup, the more indexes are created and the more space is used on the NVBU server under the NVDB folder.
By default Media manager scans every 12 hours to find 30 days old indexes and compress them.
You could change that to every 6 hours to find 10 days old or even 7 days old indexes (for example), and this will compress more indexes, more often, which in turn will reclaim space.
This is done by changing the following values under Change Settings | Server Settings | Media Manager:
Days of inactivity before an index is compressed (0 = never)
Hours between scans for indexes to be compressed (0 = never)
3) Eventually, if your environment requires more storage then assigning these resources will be the only option.