Look in /dev/oracleasm/disks and see if DATA is there and if it has the same major/minor as your /dev/mapper/my* device which is same as your /dev/dm-5 device (which should be 253, 5). If so it is probably OK as the oracleasm query may just be returning the name of the first device it finds with that major/minor. I was just saying when you did the actual definition of devices you should specify the /dev/mapper/my* rather than the /dev/dm-* so anything storing by name is using the persistent names you defined in multipath.conf rather than ephemeral names created on each boot.

I was saying in my prior post that the 11gR2 runs on RHEL6 so if it is a new setup you ought to do that rather than RHEL5.x. RHEL7 is out already and RHEL5 will be going into reduced support within a year or so.

I can't answer about the Oracle 12 as we don't use it on RHEL6.

Yep, i understood it now, thank you so much.