thefollowingtablecanhelpdeterminewhichoptionisbestfordifferent
situations.
Table 6 Summary of RAID M e thods
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 si-
multaneous
hard drive
failure?
No For RAID
1+0, if
the failed
drives
are not
mirrored to
each other
No
Yes (two
drives can
fail)
Online Spares
Further protection against data loss can be achieved by assigning an
online spare (or hot spare) to any con figuration except RAID 0. This hard
drive contains no data and is contained within the same storage sub
system as the other drives in the array. When a hard drive in the array
fails, the controller can then automatically rebuild information that was
originally on the failed drive onto the online spare. This quickly restores the
system to full RAID level fault tolerance protection. However, unless RAID
ADG is being used, which can support two drive failures in an array, in the
unlikely event that a third drive in the array should fail while data is being
rewritten to t he spare, the logical drive still fails.
NOTE:
For configurable storage servers, storage limitations are based on the
type of SAN the storage server is connected to. See the individual SAN
documentation for limitations of Windows Storage Server 2003.
HPProLiantStorageServeruserguide
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