Compression is turned off

If you use the diagnostics for your tape drive, they will report that compression is turned off, and may even prompt you to change settings in your backup software. Don't worry, it's not as bad as it first seems.

Backup Exec turns the compression off at the end of every job, and turns it on at the start of the next job (if you have it selected). So if your diagnostics check the drive in between jobs, they'll see the compression turned off, and not know that it gets turned on by Backup Exec when the job runs.