Definition - What does Data Mirroring mean?
Data mirroring refers to the real-time operation of copying data, as an exact copy, from one location to a local or remote storage medium. In computing, a mirror is an exact copy of a dataset. Most commonly, data mirroring is used when multiple exact copies of data are required in multiple locations.
Similarly, a live mirror is an exact copy of a dataset when it is immediately changed as the original is changed.
This term is also sometimes known as disk duplexing.
Techopedia explains Data Mirroring
Data mirroring can also be accomplished through disk mirroring, which involves making exact copies of data on different partitions of the same disk or on separate disks, all within the same system. With separate systems (meaning each system has at least a separate hard drive controller card), the process is called disk duplexing. Data mirroring is particularly useful for a rapid disaster recovery.