Mirror

Hard disks are an inherently unreliable component of computer systems. In the high data volume / fast turnaround world of post production, it is critical to protect data as much as possible. Disk mirroring or RAID1 is the replication of logical disk volumes onto separate physical hard disks in real time to ensure continuous availability. Mirroring can be a local or a remote technique that allows a system to automatically maintain multiple copies of data. In the event of a disk hardware failure, a mirrored system can continue to process or quickly recover data.

Normally, data is mirrored onto physically identical drives. As data is written to disk, the system automatically writes a second copy to one or more locations. The system can either a) acknowledge that the data is safely written after one drive has confirmed a successful write operation or b) only when both drives have confirmed. There is normally a performance advantage in not waiting for the second write operation.

This article is licensed under the GNU Free Documentation License found at http://www.gnu.org/copyleft/fdl.html. It uses material from the Wikipedia article at http://en.wikipedia.org/wiki/Disk_mirror.