EMC FC5300 User Manual download pdf (Page 42)

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EMC Fibre Channel Storage-System Configuration Planning

RAID Types and Tradeoffs

RAID Benefits and Tradeoffs

This section reviews RAID types and explains their benefits and

tradeoffs. You can create seven types of LUN:

• RAID 5 Group (individual access array)

• RAID 3 Group (parallel access array)

• RAID 1 mirrored pair

• RAID 1/0 Group (mirrored RAID 0 Group); a RAID 0 Group

mirrored by the storage-system hardware

• RAID 0 Group (nonredundant individual access array); no

inherent high-availability features, but can be software mirrored

if the operating system supports mirroring

• Individual unit; no inherent high-availability features but can be

software mirrored, if the operating system supports mirroring

• Hot spare; serves only as an automatic replacement for any disk

in a RAID type other than 0; does not store data during normal

system operations

Plan the disk unit configurations carefully. After a disk has been bound into a

LUN, you cannot change the RAID type of that LUN without unbinding it,

and this means losing all data on it.

The following table compares the read and write performance,

tolerance for disk failure, and relative cost per megabyte (Mbyte) of

the RAID types. Figures shown are theoretical maximums.

1 2 ... 37 38 39 40 41 42 43 44 45 46 47 ... 133 134

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EMC FC5300 User Manual Page 42