EMC CX500I Configuration Guide - Page 48

Guidelines for RAID Groups, Use a RAID 5 Group individual access array

Page 48 highlights

RAID Types and Trade-offs Guidelines for RAID Groups To decide when to use a RAID 5 Group, RAID 3 Group, mirror (that is, a RAID 1 mirrored pair or RAID 1/0 Group, a RAID 0 Group, individual disk unit, or hot spare), you need to weigh these factors: ◆ Importance of data availability ◆ Importance of performance ◆ Amount of data stored ◆ Cost of disk space The following guidelines will help you decide on RAID types. Use a RAID 5 Group (individual access array) for applications where ◆ Data availability is very important. ◆ Large volumes of data will be stored. ◆ Multitask applications use I/O transfers of different sizes. ◆ Excellent read and good write performance is needed (write performance is very good with write caching). ◆ You want the flexibility of multiple LUNs per RAID Group. Use a RAID 3 Group (parallel access array) for applications where ◆ Data availability is very important. ◆ Large volumes of data will be stored. ◆ A single-task application uses large I/O transfers (more than 64 Kbytes). The operating system must allow transfers aligned to start at disk addresses that are multiples of 2 Kbytes from the start of the LUN. Use a RAID 1 mirrored pair for applications where ◆ Data availability is very important. ◆ Speed of write access is important and write activity is heavy. Use a RAID 1/0 Group (mirrored nonredundant array) for applications where ◆ Data availability is critically important. ◆ Overall performance is very important. 2-18 EMC CLARiiON CX300, CX500, CX500i, and CX700 Storage Systems Configuration Planning Guide

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2-18
EMC CLARiiON CX300, CX500, CX500i, and CX700 Storage Systems Configuration Planning Guide
RAID Types and Trade-offs
Guidelines for RAID Groups
To decide when to use a RAID 5 Group, RAID 3 Group, mirror (that
is, a RAID 1 mirrored pair or RAID 1/0 Group, a RAID 0 Group,
individual disk unit, or hot spare), you need to weigh these factors:
Importance of data availability
Importance of performance
Amount of data stored
Cost of disk space
The following guidelines will help you decide on RAID types.
Use a RAID 5 Group (individual access array)
for applications
where
Data availability is very important.
Large volumes of data will be stored.
Multitask applications use I/O transfers of different sizes.
Excellent read and good write performance is needed (write
performance is very good with write caching).
You want the flexibility of multiple LUNs per RAID Group.
Use a RAID 3 Group (parallel access array)
for applications where
Data availability is very important.
Large volumes of data will be stored.
A single-task application uses large I/O transfers (more than 64
Kbytes). The operating system must allow transfers aligned to
start at disk addresses that are multiples of 2 Kbytes from the start
of the LUN.
Use a RAID 1 mirrored pair
for applications where
Data availability is very important.
Speed of write access is important and write activity is heavy.
Use a RAID 1/0 Group (mirrored nonredundant array)
for
applications where
Data availability is critically important.
Overall performance is very important.