Originally posted by OracleDoc
I'm confused....if you have RAC why do you want to do standby as well?
RAC = high availability
Standby = disaster recovery

In RAC environment, in most cases all the nodes of the cluster are located in the same geographical location, usualy in the same building/room. So for example if the ceiling of that building colapses, probably all the nodes of the RAC will be damaged. So what good does it do that you had RAC? That is why it is not unusual to have a standby database on some distant location that covers you in the events of such "environmental disasters".