Disk Array Unit Overview 1-13
RAID Configurations
Available DAU RAID configurations are shown in Table 1-4.
Table 1-4. RAID Configurations
RAID Level RAID0 RAID1 RAID5 RAID10
Number of physical drives in configuration 1, 3, 5, 10,
15
1+1 2+1 to 14+1 2+2 to 7+7
Number of logical drives per subsystem 1,024 max.
With 36-GB disks 35.7 to
536.1GB
35.7GB 71.4 to
500.3GB
71.4 to
250.1GB
With 73-GB disks 71.6 to
1074GB
71.6GB 143.2 to
1002GB
143.2 to
501.2GB
Storage capacity per
logical drive
With 146 GB disks 142.9 to
2144GB
142.9GB 285.8 to
2001GB
285.8 to
1000GB
* A combination of disk modules of the same capacity and same rotational speed are required for
configuring logical drives.
Characteristics of the RAID levels are shown in Table 1-5.
Table 1-5. RAID Level Characteristics
Level Function Advantage Disadvantage
RAID0 Striping Highest data read/write rate
Maximum storage capacity
Data recovery disabled
(Fault in a single disk
module causes data to be
lost.)
RAID1 Mirroring Data recovery enabled Low-speed data writing
All data is written to two
disk modules.
Minimum data recovery time The required disk capacity
is twice the used storage
capacity.
RAID5 Striping of data and
redundant data
Data recovery enabled Three or more disk
modules are required.
Larger capacity is available for
users because the capacity of
redundant data is smaller than
that of RAID1.
The required storage
capacity is one extra
physical disk per rank.
High-speed data write
RAID10 Use of both mirroring
and striping
Data recovery enabled Four or more disk modules
are required.
High-speed data read/write The required storage
capacity of disk module is
twice the used storage
capacity.
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