From Wikipedia, the free encyclopedia.
The RAID controller is best
described as a device in which servers and storage intersect. The controller
can be internal to the server, in which case it is a card or chip, or external,
in which case it is an independent enclosure, such as a NAS (network-attached storage). In either case,
the RAID controller manages the physical storage units in a RAID system and
delivers them to the server in logical units (e.g., six physical disks may be
used to ensure that one drive stays correctly backed up, but the server sees
only one drive).
While a RAID controller is almost
never purchased separately from the RAID itself, the controller is a vital
piece of the puzzle and therefore not as much a commodity purchase as the
A RAID (Redundant_array_of_independent(or inexpensive)_disks)
system is simply a collection of disk drives that employs two or more drives in
combination for fault tolerance and performance. RAID drives vary in robustness
from Level 0 (data striping without redundancy) to Level 5 (data striping at
the byte level with stripe error correction information).