User guide

Chapter 1 Overview
> 1.2 Configuration
ETERNUS DX60/DX80/DX90 Disk storage system User Guide
28
Copyright 2010 FUJITSU LIMITED
P3AM-3042-06ENZ0
• RAID1+0 (striping of pairs of disks for mirroring)
RAID1+0 combines the performance of RAID0 (striping) with the reliability of RAID1
(mirroring).
Figure 1.3 RAID1+0 concept
• RAID5 (striping with distributed parity)
Data divided into units of blocks and allocated across multiple disks together with parity
information created from the data. If one disk fails, the remaining data and parity blocks are
sufficient to allow the recovery of the lost data.
Figure 1.4 RAID5 concept
HDD3
HDD7
D
D’
HDD2
HDD6
C
C’
HDD1
HDD5
B
B’
HDD0
HDD4
A
A’
Striping (RAID0)
Mirroring (RAID1)
Data writing request
ABCD
Mirroring
Mirroring
Mirroring
Mirroring
A
E
I
M
ABCD
Data writing request
B
F
J
P
M, N, O, P
C
G
P
I, J, K, L
N
D
P
E, F, G, H
K
O
H
L
P
Create Parity Data
P A, B, C, D
A B DC
HDD0 HDD1 HDD2 HDD3 HDD4
Parity for data A to D
Parity for data E to H
Parity for data I to L:
Parity for data M to P
Parity M, N, O, P
Parity I, J, K, L
Parity E, F, G, H
Parity A, B, C, D