The two clusters and sites are connected by two separate networks that provide the replication transport.
The cluster peering network is an IP network that is used to replicate cluster configuration information between the sites. The shared storage fabric is an FC or IP connection that is used for storage and NVRAM synchronous replication between the two clubers. For MetroCluster IP, replication uses both iWARP for NVRAM and iSCSI for disk replication. All storage is visible to all controllers through the shared storage fabric.

Fault-tolerant storage infrastructurs

If a failure prevents host access to a volume in a GAD pair, read and write I/O can continue to the pair volume in the other storage system to provide continuous server I/O to the data volume.

Failover clustering without storage impact

In a server-cluster configuration with global-active device, the cluster software is used to perform server failover and failback operations, and the global-active device pairs do not need to be suspended or resynchronized.

Server load balancing without storage impact

When the I/O load on a virtual storage machine at the primary site increases global-active device enables you to migrate the virtual machine to the paired server without performing any operations on the storage systems.

As shown in this example, the server virtualization function is used to migrate virtual machine VM3 from the primary-site server to the secondary-site server. Because the GAD primary and secondary volumes contain the same data, you do not need to migrate any data between the storage systems.