Check your 'global' file, and look for this
# DbXXXXXXXXXLimit=GBytes
# The following global options are used by Data Protector
# omnidbutil -extendtblspace to limit the database size of
# Data Protector internal database. omnidbutil
# will not allow to add tablespace extensions if this would
# increase the total size of the specified tablespace to more
# than specified by this option.
# Use these options carefully!
One of the options is "DbFnamesDatLimit". In my 'global' file, it is set to 48
DbFnamesDatLimit=48
Based on the Product Announcements Guide, this is the hard limit
I would suggest that you go through your Sessions in the Internal Database context, start with the oldest one, and see if it needs to be kept. If not, find the media used for this backup, and export it.
This can be done from the GUI, I have always found it easier from the command line
omnidb -session to get a list of sessions in the IDB, you may want to re-direct this to a file
omnidb -session [session_id] -media to find media for a session
omnimm -export [media label, or medium id] Media used for thsi session
When you export the media, everything about backups taken to that media is deleted from the IDB, including backed up filenames
If you have to keep media for long periods of time, consider removing the Catalog protection. This will remove the associated filenames from the session. If you needed to REstore an individual file, you would have to Export/IMport the media, and reset Catalog protection