Hi
Ok just because its available in AIX doesn't necessarily mean its visible. Are the drives in question SAN attached (fibre)? If so use tapeutil to verify that AIX can communicate with the drive :
tapeutil -f /dev/rmt1 inquiry 83
root@tsmsvrbkp:/# tapeutil -f /dev/rmt2 inquiry 83
Issuing inquiry for page 0x83...
Inquiry Page 0x83, Length 74
0 1 2 3 4 5 6 7 8 9 A B C D E F 0123456789ABCDEF
0000 - 0183 0046 0201 0022 4942 4D20 2020 2020 [..F..."IBM ]
0010 - 554C 5433 3538 302D 5444 3320 2020 2020 [ULT3580-TD3 ]
0020 - 3030 3037 3832 3834 3738 0183 0008 5005 [0007828478...P.]
0030 - 0763 0F11 3A06 0194 0004 0000 0001 0193 [.c..:.........]
0040 - 0008 5005 0763 0F51 3A
06 [..P..c.Q:. ]
This will prove that AIX can talk to the drive. It also confirms which drive the rmt is by the last characters (in bold) so in my case rmt2 is drive6.
If tapeutil hangs, check the SAN port and see if the drive is logged in ok. If not, I would power cycle the drive and/or bounce the san port.
Cheers