Fujitsu Eternus DX60 User Manual page 30

Chapter 1 Overview
> 1.2 Configuration
• RAID6 (striping with distributed double parities)
Store two different parities on different disks (double parities) to recover from up to two disk
failures.
Figure 1.6
User capacity for each RAID level
User capacity varies according to the RAID level.
Table 1.1
capacity for each RAID level.
Table 1.1
100GB SSD
200GB SSD
146GB SAS disk
300GB SAS disk
450GB SAS disk
600GB SAS disk
750GB Nearline SAS disk
1TB Nearline SAS disk
2TB Nearline SAS disk
*1: The above User Capacities are based on a 1MB = 1,024
P3AM-3042-06ENZ0 ETERNUS DX60/DX80/DX90 Disk storage system User Guide
Data writing request
A B C
A B C
A B C
E F G
I J P1
I, J, K, L
M P1 P2
M, N, O, P M, N, O, P
HDD0 HDD1 HDD2
Parity for data A to D: Parity1
Parity for data E to H: Parity1
Parity for data I to L:
Parity for data M to P: Parity1
RAID6 concept
shows the user capacity per disk.
User capacity per disk
Product name
D
D Create parity data
P1 P2
A, B, C, D
D
P1 P2
E, F, G, H E, F, G, H
P2
I, J, K, L K
N O
HDD3 HDD4
and Parity2
A, B, C, D
E, F, G, H and Parity2
Parity1 I, J, K, L and Parity2
and Parity2
M, N, O, P
Table 1.2 shows the formula for calculating the user
User Capacity per Disk (*1)
92,672MB
186,624MB
135,936MB
279,040MB
419,072MB
559,104MB
702,976MB
937,728MB
1,866,240MB
2
Byte metric.
30
A, B, C, D
H
L
P
HDD5
A, B, C, D
E, F, G, H
I, J, K, L
M, N, O, P
Copyright 2010 FUJITSU LIMITED