The other answer describes what to do if the LTO 7 tapes are pre-formatted as Type M (which answers the details of the question, but is left ambiguous in the main title question, so I will add my own situation in case it helps someone).
As mentioned by @Tonny, if they are not formatted for Type M then they will never show the additional storage capacity. To format for Type M for the Quantum SuperLoader 3, perform the following steps:
- Ensure all Backup Exec services are stopped, meaning no jobs are running.
- Install XTalk Management Console (available from Quantum's website) onto the server that has the tape library attached.
- Load the tapes into the library.
- Use the SuperLoader 3 web management console to move the tapes from the library into the drive.
- Run Xtalk Management Console.
(If the device isn't found, click "Rescan". Ensure Backup Exec services are stopped.)
- In the middle pane, there is the task "Initialize_Type_M_LTOC"; run that. It takes about 30 seconds to complete.
- Move the tape from the drive back into the library.
- Repeat moving the tapes into the drive, formatting, and moving them out for all tapes.
- When done, you can restart the Backup Exec services.
It would be significantly better to find an automated way to run through all tapes within the library and reformat them as Type M; if I can find a way, I'll try to update here.