HP StorageWorks 4000s NAS 4000s and 9000s Administration Guide - Page 60

parity data.

Page 60 highlights

Storage Management Overview 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 Maximum number of hard drives RAID 0 Striping (no fault tolerance) N/A RAID 1+0 Mirroring N/A Tolerant of single hard No drive failure? Tolerant of multiple No simultaneous hard drive failure? Yes For RAID 1+0, if the failed drives are not mirrored to each other RAID 5 Distributed Data Guarding 14 Yes RAID ADG Advanced Data Guarding Storage system dependent Yes No Yes (two drives can fail) 60 NAS 4000s and 9000s Administration Guide

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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)