voting disk distribution on 2 LUNs

Hello,

afaik Oracle RAC needs an odd number of voting disks, which would be 3 for a 2 node RAC. Furthermore more then half of voting disks must be operational otherwise both instances fail.

I've got 2 LUNs one in the prime data center and another one in the backup data center. 

How shall I distribute the voting disks over the 2 LUNs???

If I create 2 partitions on the prime LUN and 1 on the backup, means Oracle would fail in case I loose the prime LUN. Could I use 5 voting disks with 3 on the prime and 2 on the backup so that if prime fails I still have 2 voting disks left?? Or do I understand something wrong about the voting disks?