## Replication

There are two kinds of replication:

• Mirrors or Clones—When the data for the source disk is duplicated by the disk array into another disk in the same storage system, the destination disk is called a mirror or clone of the source disk. This is called local replication.

• Remote Replication—When the data for the source disk is being duplicated by the disk array into another disk in a remote storage system, then the source disk and the remote disk are in a replication relationship. Based on the distance and bandwidth availability between local and the remote site, remote replication is categorised under the following types:

– Synchronous—The local disk array does not respond to the write command on the local LUN until the data is also written to the remote LUN.

– Asynchronous—The local disk array does not immediately write the data to the remote LUN. The changes to the local LUN are batched into a delta dataset and periodically sent to the remote LUN.