In Backup Exec 2012 it may be observed that the compression ratio is 1.0:1 or 1:1 when compression is turned on for the backup jobs targeted to tape. Upon further inspection of the tapes it is found that compression IS working correctly even though the Backup Exec UI reports a 1:1 ratio.
To confirm that compression is working correctly please use Tracer.exe as described in the following technote: TECH50960
This is a graphical issue and does not reflect the actual performance of tape devices and associated hardware.
A hotfix is now available for this issue in the current version(s) of the product(s). Refer to the Hotfix link below to obtain the hotfix needed to resolve the issue.
Backup Exec 2012 revision 1798 Hotfix 189571, Device Driver Installer DDI20120715 (July 15th, 2012) - http://www.symantec.com/docs/TECH189571