Figure 7 Raid6-Fr Concept; Table 3 Raid Level Comparison - Fujitsu ETERNUS DX100 S4 Design Manual

2. Basic Functions
RAID Functions
●
RAID6-FR (Provides the High Speed Rebuild Function, and Striping with Double Distributed Parity)
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 7 RAID6-FR Concept

A B
A B
P2
K G, H, I
P1
M, N, O R
P1
S, T, U
X
FHS
FHS
Drive#0 Drive#1
■
Reliability, Performance, Capacity for Each RAID Level
Table 3 shows the comparison result of reliability, performance, capacity for each RAID level.

Table 3 RAID Level Comparison

RAID level
RAID0
RAID1
RAID1+0
RAID5
RAID5+0
RAID6
RAID6-FR
◎: Very good ¡: Good △: Reasonable ´: Poor
Fujitsu Storage ETERNUS DX100 S4/DX200 S4, ETERNUS DX100 S3/DX200 S3 Hybrid Storage Systems Design Guide (Basic)
Data writing request
A B C D
C
Create parity data
P1 P2
C A, B, C A, B, C
J H L
P2 FHS
P, Q, R
M
P1 P2
V, W, X V, W, X
V
Drive#2 Drive#3 Drive#4
RAID6-FR ((3D+2P) × 2 + 1HS)
Reliability
´
¡
¡
¡
¡
◎
◎
21
Copyright 2023 Fujitsu Limited
D
Create parity data
D E F
P1 FHS
J, K, L I
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
Performance (*1)
◎
¡
◎
¡
¡
¡
¡
P1 P2
D, E, F D, E, F FHS
P2 P1
J, K, L G 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
Capacity
◎
△
△
¡
¡
¡
¡
P3AM-7642-32ENZ0