RAID

raid

R–Redundant

A–Array of

I–Inexpensive/Independent

D–Disks

RAID LEVEL 0

implements data stripping (files are stripped across disks)

Pro: Least cost, very fast on read and write

Con: No fault tolerance (any disk failure results in data loss

RAID 1

implements data mirroring

Pros: Excellent Protection against crashing

Cons: Slow on write, costly and inefficien

RAID 2

implements bit stripping with ECC (bit-level striping with Hamming codes for error correction)

Pros: Good performance on both read and write. Good protection. Cons: Hamming code generation is slow, still expensive, no commercial use

RAID 3

implements bit stripping with parity disk

Pros: Very good performance on read, write. Good protection. Efficient. Can be used in applications that need access to long sequential records

Cons: Complicated controller desig

RAID 4

implements data stripping with parity drive; combines Level 0 and 3; A read accesses all the data disks; A write accesses all data disks plus the parity disk

Pros: Fast on read. Good protection

Cons: Very slow write speed. Difficult data rebuild. Complex design. Not used in real lif

RAID 5

implements data stripping with rotational parity (The parity block is rotated amongst all the drives so that one single drive does not get accessed more than any other drive)

Pros: Fastest read speed, decent write speed. Good protection. Cost effective = commercial success

Cons: Most complex design. Difficult to rebuilt data

RAID 6

implements data stripping with dual error protection

Pros: Excellent protection, can sustain multiple hits.

Cons: Complex to implement.

1 + 0 implements data stripping with mirror drive.

Pros: Excellent protection. Good read and write speed compared to others.

Cons: Very expensive.