RAID LEVEL 6: Stripping with Double Distributed Parity Blocks

Server
Disk 0
Disk 1
Disk 2
Disk 3
Disk 4
A
B
C
A0
A1
A2
Ap
Aq
B0
B1
Bp
Bq
B2
C0
Cp
Cq
C1
C2
Parity Generator (p,q)

Click on the diagram to see Raid 6 in action

RAID 6 extends RAID 5 by using block-level striping with two parity blocks, instead of one, distributed across all member disks.
RAID 6 requires at least 4 drives to implement.

Characteristics & Advantages

  • Very fast Read data transfer rate
  • Extremely high data fault tolerance
  • Can sustain two drive failures because of the two parity checks, data is still accessable.

Disadvantages

  • Transaction rate equal to a single disk drive at best (if spindles are synchronized)
  • Parity calculation overhead slows down the Write data transaction rate
  • Requires n+2 drives to implement because of dual parity scheme

Recommended Applications

  • File Servers
  • Database Servers
  • Application Servers
  • Practically any servers with limited data drives