●
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
RAID6-FR ((3D+2P) × 2 + 1HS)
H
FHS
V
E
I
S
C
J
A
K
FHS
X
W
F
FHS
N
T
G
Q
U
D
O
FHS
B
R
FHS
P
FHS
M
L
A
B
C
D
Data writing request
A
B
C
D
Create parity data
Create parity data
P1
A, B, C
P1
P, Q, R
P2
P, Q, R
P1
V, W, X
P1
M, N, O
P2
M, N, O
P1
D, E, F
P2
J, K, L
P2
D, E, F
P1
J, K, L
P1
S, T, U
P2
G, H, I
P1
G, H, I
P2
S, T, U
P2
A, B, C
P2
V, W, X
Drive#0
Drive#1
Drive#2
Drive#3
Drive#4
Drive#5
Drive#6
Drive#7
Drive#8
Drive#9
Drive#10
Parity for data A, B, C: P1
A, B, C
and P2
A, B, C
Parity for data D, E, F: P1
D, E, F
and P2
D, E, F
Parity for data G, H, I: P1
G, H, I
and P2
G, H, I
Parity for data J, K, L: P1
J, K, L
and P2
J, K, L
Parity for data M, N, O: P1
M, N, O
and P2
M, N, O
Parity for data P, Q, R: P1
P, Q, R
and P2
P, Q, R
Parity for data S, T, U: P1
S, T, U
and P2
S, T, U
Parity for data V, W, X: P1
V, W, X
and P2
V, W, X
:
Fast recovery Hot Spare: FHS
■
Reliability, Performance, Capacity for Each RAID Level
shows the comparison result of reliability, performance, capacity for each RAID level.
Table 5
RAID Level Comparison
RAID level
Reliability
Performance (*1)
Capacity
RAID0
´
◎
◎
RAID1
¡
¡
△
RAID1+0
¡
◎
△
RAID5
¡
¡
¡
RAID5+0
¡
¡
¡
RAID6
◎
¡
¡
RAID6-FR
◎
¡
¡
◎
: Very good
¡
: Good
△
: Reasonable
´
: Poor
*1:
Performance may differ according to the number of drives and the processing method from the host.
2. Basic Functions
RAID Functions
23
Design Guide
Summary of Contents for ETERNUS AF S3 Series
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