Figure 7 Raid6-Fr Concept; Table 2 Raid Level Comparison - Fujitsu ETERNUS AF250 Design Manual

1. Function
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
R
M, N, O
P1
S, T, U
X
FHS
FHS
Drive#0 Drive#1
■
Reliability, Performance, Capacity for Each RAID Level
Table 2 shows the comparison result of reliability, performance, capacity for each RAID level.

Table 2 RAID Level Comparison

RAID level
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.
Data writing request
A B C D
C
Create parity data
P1 P2
C
A, B, C A, B, C
L
J H
FHS
P2
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
´
¡
¡
¡
¡
◎
◎
FUJITSU Storage ETERNUS AF250 S2, ETERNUS AF250 All-Flash Arrays Design Guide (Basic)
Copyright 2019 FUJITSU LIMITED
D
D F
E
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)
◎
¡
◎
¡
¡
¡
¡
21
Create parity data
P1 P2
FHS
D, E, F D, E, F
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
◎
△
△
¡
¡
¡
¡
P3AG-1822-09ENZ0