Assuming Windows OS, if the tape drives are listed in device manager, right click on a tape drive and select properties. Compression should be click box avalable there.

There is nothing about compression on the device mgr properties of the drives.

What backup software are you using with the TL?

-Bob

Symantec Backup Exec 2010 R3

It's already checked.

From within the BE\Devices view Right click your drives listed under the library select Properties\Configuration and check the Enable compression box.

-Bob

I have 14 tapes in the library. 7 are dedicated to one specific server backup and 7 are for another server.  The first 7 are 1:1 and the other 7 vary from 1:2 - 1:3 depending on the tape.

If compression is working, why do the TL4000  drives show 'no compression' in the web interface?

From your Devices view again within BE, select the Slots device under your library. Once you select slots all your media will show up in the right side pane. Scroll the pane to right to view the Compression Ratio for each piece of media, anything other than 1:1 listed will indicate that compression is working.

-Bob

The web interface should change to YES when the drive is actually writing data...(during a backup), then switch back to NO when Idle.

-Bob

I just ran a small backup and kept refreshing the interface, but it never changed to yes.