Snapshots and coordinated snapshots within Remote Copy

A snapshot is a point-in-time virtual copy of a virtual volume. Under normal operating conditions, a snapshot includes only new data saved to the primary virtual volume since the last synchronization with the secondary virtual volume.

Snapshots are created to track updates to the primary volume when new data is not immediately sent to the secondary volume, like in asynchronous periodic volume groups.

To minimize the amount of data sent over the network during resynchronization, Remote Copy creates snapshots of the updates to the primary volumes. Only these snapshots are sent to secondary volumes to back up systems.

Remote Copy automatically creates snapshots when a system, or all links, go down as a result of failure or scheduled downtime.

Coordinated snapshots are snapshots that are created at the same point in time on both the primary and secondary systems. Coordinated snapshots are an important aspect of asynchronous streaming volume groups.