how to add failure group in ASM for Oracle 10g

Hi,

I have oracle 10.1 crs running in IBM AIX 5L. I created an ASM diskgroup with 1 logical disk based on external redundancy (3 x 146GB DS4300 Fibre Channel physical disk on hardware RAID5).

As i had just encountered a hardware failure (2 x 146GB Hard disk failure), my whole database went down.

I was wondering if i could add in another 1 x logical disk (3 x 146GB DS4300 Fibre Channel physical disk on hardware RAID5) to mirror my existing diskgroup for better redundancy.

Is this kind of configuration supported?Has anyone done this before? Can anyone kindly provide me with the commands / steps to do this. Thanks.

Regards,
Alec