RAID 1 - Mirroring - Fault Tolerance
Definition: RAID 1 mirroring is an arrangement of hard disks that creates an exact copy (or mirror) of a set of data on two or more disks. This is useful when read performance or reliability are more important than data storage capacity.
RAID I, for example, writes two copies of the data simultaneously on two separate drives. This is called
fault tolerant because if one of the mirrored drives suffers a mechanical failure (e.g.
spindle failure) or does not respond, the remaining drive will continue to function. The
RAID 1 configuration is performed either by a hardware
RAID controller… or performed in
software. It is suited to applications requiring high fault tolerance at a low cost and
where a duplicated set of data is more secure than using parity. RAID 1 is popular for
accounting and other financial data. It is also commonly used for small database systems,
enterprise servers, and home PCs where a fairly inexpensive fault tolerance is required.