RAID



Originally 'Redundant Arrays of Inexpensive Disks'. A project at the computer science department of the University of California at Berkeley, under the direction of Professor Katz, in conjunction with Professor John Ousterhout and Professor David Patterson.

The following standard RAID specifications exist:
RAID 0 Non-redundant striped array
RAID 1 Mirrored arrays
RAID 2 Parallel array with ECC
RAID 3 Parallel array with parity
RAID 4 Striped array with parity
RAID 5 Striped array with rotating parity


The basic idea of RAID (Redundant Array of Independent Disks) is to combine multiple inexpensive disk drives into an array of disk drives to obtain performance, capacity and reliability that exceeds that of a single large drive. The array of drives appears to the host computer as a single logical drive. The Mean Time Between Failure (MTBF) of the array is equal to the MTBF of an individual drive, divided by the number of drives in the array. Because of this, the MTBF of a non-redundant array (RAID 0) is too low for mission-critical systems. However, disk arrays can be made fault-tolerant by redundantly storing information in various ways.

Data Recovery tip #17: If possible, always have and make multiple backups, and when possible be sure to store critical data remotely.