We make Aux Copies to tape using a Global Secondary Copy Policy. Primary backups are made using SW Compression and Commvault Deduplication. Tapes are often < 75-80% Full before being marked as Full (physical end of media). Result is 20 to 25% extra tape usage / additional costs.
Is this expected behaviour or is there something I can do about this?
For the Global Secondary Copy are you also using Hardware Compression when writing to Tape?
Likewise is encryption also enabled by any chance?
Hardware Compression was enabled but we disabled it yesterday and will evaluate next week after the Weekly backups to Tape if it makes a difference.
We use SW Compression and Deduplication on the Primary Backup but no encryption.
After disabling Hardware Compression the situation seems at best a bit better (or no difference at all). LTO6 tapes often contain no more than 1,8 or 1,9 TB of data (according to LTO standards, should be 2,5 TB).
I would recommend to open a Support Ticket to check this further.