The following is assuming that networking has been configured correctly and two VRAs are being used for redundancy.
There are different approaches to ensuring reliable redundancy. One of these methods is to have the Primary/Backup Apps split 50/50 between the two VRAs.
For example, in the below example, these 2 VRA systems are running with 4 Primary applications on one, and the 4 backups on the other.
This is easy to manage, however if the primary VRA loses power, all apps would failover at the same time.
Another configuration example would be to have half and half. Half the primaries on one VRA, and the other half on the second.
This can be more confusing when managing multiple Virtual Racks, but means if one Machine loses power, only half of the apps fail over at once.