
Storage Management Overview
60 NAS 4000s and 9000s Administration Guide
Advantages
■ High read performance.
■ High data availability-any two drives can fail without loss of critical data.
Disadvantages
■ Relatively low write performance (lower than RAID 5), due to the need for two sets of
parity data.
The table below summarizes the important features of the different kinds of RAID supported
by the Smart Array controllers. The decision chart in the following table may help determine
which option is best for different situations.
Table 3: Summary of RAID Methods
RAID 0
Striping (no
fault
tolerance)
RAID 1+0
Mirroring
RAID 5
Distributed
Data
Guarding
RAID ADG
Advanced
Data
Guarding
Maximum number of
hard drives
N/A N/A 14 Storage
system
dependent
Tolerant of single hard
drive failure?
No Yes Yes Yes
Tolerant of multiple
simultaneous hard drive
failure?
No For RAID
1+0, if the
failed drives
are not
mirrored to
each other
No Yes
(two drives
can fail)
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