What is Disk Mirroring?

Disk mirroring is the process of replicating logical disk volumes onto separate physical hard disks in real time to ensure continuous availability. A mirrored volume is a complete logical representation of separate volume copies. In disaster recovery context, mirroring data over long distance is referred to as storage replication. There are varied technologies used for replicating data and depending on the technology used, replication can be performed synchronously, asynchronously, semi-synchronously, or point-in-time. Replication is performed through microcode on the disk array controller or through server software. It is typically a proprietary solution, and is therefore not compatible between various storage vendors. Mirroring in most instances is synchronous. Synchronous writing achieves a recovery point objective of zero data loss.