Oracle Database Discussions

I'm trying to design and implement a solution where there is a Oracle RAC with ASM and 4 nodes. 2 nodes are in the primry site and 10km away there is the secondary datacenter (second site) with 2 other nodes.

Acctually we only have 1 site and 2 nodes running Oracle RAC.

I don't have too much experience on RAC on extended distance so I'm trying to research and read all documentation I can.

Unfortunally I haven't be able to find much documentation. I want to know if I have to buy other software components like something that can do the mirror between the both storage. I use HP so I read about contnuous access but I'm not sure if it is compatible with all the solution. I read about mirror/ux (my operating system is hpux) but I think that these won't help me because I'm using ASM (is only for LVM, right?)

So maybe the best solution is to use mirror at oracle level inside ASM, I don't want to use this because it would charge more the database, I wanted to do it al storage level or oeprating system level, but I didn't find any answer yet.

Please if anybody cant help me with his/her experience, I will be very greatfull. My primary concern is replication between the 2 storage (one in the primary site and the other in the second site).

About communication, Í haven't worried yet because we have FC.