MIRRORING

8/3/96

Mirroring is a technique that allows the contents of a disk drive to be continuously backed up onto a second drive. Mirroring is used in situations where conventional once a day/week backup techniques would result in unacceptable data loss in the event of drive failure. Mirroring is also used occasionally to do drive copies in situations where conventional drive copying is difficult.

Mirroring requires two identical drives (or, at least, a second drive larger than the first). It offers good protection against catastrophic failure of the primary drive. It does not protect against corruption of data structures caused by problems in the attached computer.

Mirroring is often implemented in hardware; in disk drivers; or in operating systems including Novell. Tekram, Buslogic, and other companies offer mirroring controllers for IDE and SCSI drives.