RAID 0 - Speed (Widely Used)
RAID level 0 is disk striping only, which interleaves data across multiple disks
for performance. Widely used for gaming, RAID 0 has no safeguards against failure.
RAID 1 - Fault Tolerance
(Widely Used)
Uses disk mirroring, which provides 100% duplication of data. Offers highest reliability,
but doubles storage cost. RAID 1 is widely used in business applications.
RAID 2 - Speed
Instead of single bytes or groups of bytes (blocks), bits are interleaved (striped)
across many disks. The Connection Machine used this technique, but this is rarely
used because 39 disks are required.
RAID 3 - Speed and Fault
Tolerance
Data are striped across three or more drives. Used to achieve the highest data transfer,
because all drives operate in parallel. Using byte level striping, parity bits are
stored on separate, dedicated drives. |
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RAID 4 - Speed and Fault
Tolerance
Similar to RAID 3, but uses block level striping. Not often used.
RAID 5 - Speed and Fault
Tolerance (Widely Used)
Data are striped across three or more drives for performance, and parity bits are
used for fault tolerance. The parity bits from two drives are stored on a third
drive and are interspersed with user data. RAID 5 is widely used in servers.
RAID 6 - Speed and Fault
Tolerance
Highest reliability because it can recover from a failure of two disks, but not
widely used. Similar to RAID 5, but performs two different parity computations or
the same computation on overlapping subsets of the data.
RAID 10, RAID 100
- Speed and Fault Tolerance
RAID 10 is RAID 1 + 0. The drives are striped for performance (RAID 0), and all
striped drives are duplicated (RAID 1) for fault tolerance.
RAID 100 is RAID 10 + 0. It adds a layer of striping on top of two or more RAID
10 configurations for even more speed. |