Hitachi Compute Rack CR 210H User Manual page 26

RAID1
Figure 3-2: RAID1 method
Data is stored on one HDD (data disk) and the other one (mirrored disk).
Advantage:

Provides 100% data redundancy, thus enabling easy switching between two
disks to continue read or write processing if a disk failure occurs. HDD
interchange also allows data reconstruction without shutdown operations.
Disadvantage:

– A double HDD capacity is required because a mirrored disk of the same
capacity should be installed.
– An attempt to read or write data during data rebuild causes a decrease in
processing performance.
Number of HDDs required: 2

3-4
Host
Array Controller
Block 1
Block 2
Disk 1
(Data Disk)
System Unit Functions
Hitachi Compute Rack 210H User's Guide
Data
Block 1
Block 2
Disk 2
(Mirrored Disk)