I am trying to take advantage of the Atape driver's Alternate Pathing feature.  
When I do a lsdev -Cc tape I see:

rmt0 Available 0A-08-02-PRI IBM 3592 Tape Drive (FCP)
rmt1 Available 0A-08-02-PRI IBM 3592 Tape Drive (FCP)
rmt2 Available 0A-08-02-PRI IBM 3592 Tape Drive (FCP)
rmt3 Available 0A-08-02-PRI IBM 3592 Tape Drive (FCP)
rmt4 Available 0A-08-02-ALT IBM 3592 Tape Drive (FCP)
rmt5 Available 0A-08-02-ALT IBM 3592 Tape Drive (FCP)
rmt6 Available 0A-08-02-ALT IBM 3592 Tape Drive (FCP)
rmt7 Available 0A-08-02-ALT IBM 3592 Tape Drive (FCP)
smc0 Available 0A-08-02     IBM 3584 Library Medium Changer (FCP)

But when I do a backup to the primary drives and then disconnect the cable to 
test a failure, the alternate drive(s) do not take over.

Within TSM I have 4 drives (rmt0-3 defined).

Am I missing a step?

Thanks for your help.

DW