2. Basic Functions
RAID Functions
●
RAID6 (Striping with Double Distributed Parity)
Allocating two different parities on different drives (double parity) makes it possible to recover from up to
two drive failures.
●
RAID6-FR (Striping with Double Distributed Parity which Provides High-Speed Rebuild Capabilities)
Distributing multiple data groups and reserved space equivalent to hot spares to the configuration drives
makes it possible to recover from up to two drive failures. RAID6-FR requires less build time than RAID6.
Figure 2
RAID6-FR Concept
A
A
P2
K
P1
M, N, O
P1
X
FHS
Drive#0
Drive#1
Data writing request
A
B
C
B
C
Create parity data
P1
P2
B
C
A, B, C
A, B, C
J
H
G, H, I
FHS
P2
R
P, Q, R
M
P1
P2
S, T, U
V, W, X
V, W, X
V
FHS
Drive#2
Drive#3
Drive#4
RAID6-FR ((3D+2P) × 2 + 1HS)
D
D
D
E
F
P1
FHS
L
I
J, K, L
P1
P2
O
P, Q, R
M, N, O
FHS
S
W
Drive#5
Drive#6
Drive#7
Parity for data A, B, C: P1
Parity for data D, E, F: P1
Parity for data G, H, I: P1
Parity for data J, K, L: P1
Parity for data M, N, O: P1
Parity for data P, Q, R: P1
Parity for data S, T, U: P1
Parity for data V, W, X: P1
:
Fast recovery Hot Spare: FHS
34
Create parity data
P1
P2
FHS
D, E, F
D, E, F
P2
P1
G
J, K, L
G, H, I
N
Q
P
P2
S, T, U
T
U
Drive#8
Drive#9
Drive#10
and P2
A, B, C
A, B, C
and P2
D, E, F
D, E, F
and P2
G, H, I
G, H, I
and P2
J, K, L
J, K, L
and P2
M, N, O
M, N, O
and P2
P, Q, R
P, Q, R
and P2
S, T, U
S, T, U
and P2
V, W, X
V, W, X
Design Guide