A multi-cluster grid can be run in "Preferred" or "Balanced Mode". "Preferred Mode" is where a host has virtual devices online to only one cluster in the grid. All allocations are then directed to the devices in that one cluster. "Balanced Mode", on the other hand, is where a host has virtual devices online to two or more clusters in the grid. Allocations from the host could then select virtual devices from multiple clusters. Refer to information APAR II14516 and Load balancing considerations for additional considerations when running in balanced mode.