Even the most resilient storage appliances are subject to user error, power failures, site failures, periodic maintenance, and hardware refreshes. Adding a redundant array as a replication target, using array-based replication or SQL Server replication, will protect the data and prevent data loss. However, in both scenarios, a failover and interruption of service must take place as the host is remapped to a storage target or the failover cluster instance or availability group instance moves to a different host.
In a typical multi-array environment without metro node, planned or unplanned storage outages would result in a service interruption as the storage volumes are reconnected or cluster failover occurs.
Virtualizing storage volumes from the physical array and maintaining a consistent and reliable storage connection minimizes or eliminates downtime. Metro node allows a virtual volume to be mirrored across supported arrays of the same or different type. Virtual volume mirrors can be created, synchronized, and unmirrored without any disruption to the host. If the mirror is severed, the mirror will self-heal when the connection to the mirror is re-established.