Disk mirroring,

Definition of Disk mirroring:

1. Backup technique in which data is written simultaneously to two or more hard disks. In the event of a disk failure, the computer automatically switches access to the next disk, without loss of data or interrupting data processing. In some configurations, backup disks are maintained at a remote site (mirror site) for additional safety. Also called data mirroring. See also redundant array of independent disks (RAID).