Smart Array 5i Plus Controller and Battery Backed Write Cache Enabler User Guide

Configuring an Array
7-14 Compaq Smart Array 5i Plus Controller and Battery Backed Write Cache Enabler User Guide
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Writer: Amy L. Laffitte File Name: h-ch7 Configuring an Array
Codename: Executor Part Number: 266328-001 Last Saved On: 2/8/02 10:39 AM
The Stripe Size box has a drop-down menu that lets you select the width of a data
stripe. (This width corresponds to the size of a data block on each hard drive in the
logical volume, as described in Appendix D).
Each RAID level supports several stripe widths (Table 7-2); the default stripe size
initially displayed by ACU is chosen for optimum performance under the most
common operating conditions. Table 7-3 suggests how to optimize the stripe width
for different types of application.
Table 7-2: Supported Stripe Sizes for a Given RAID Level
Fault Tolerance Level Supported Stripe Sizes (KB) Default (KB)
RAID 0 8, 16, 32, 64, 128, 256 128
RAID 1 or 1+0 8, 16, 32, 64, 128, 256 128
RAID 5 8, 16, 32, 64 16
Table 7-3: Optimum Stripe Size for a Given Application
Type of Server Application Suggested Stripe Size Change
Mixed read/write Accept the default value
Mainly sequential read (such
as audio/video applications)
Use larger stripe sizes for best
performance
Mainly write (such as image
manipulation applications)
Use smaller stripes for RAID 5
Use larger stripes for RAID 0, RAID 1+0,
RAID 1
The Logical Drive Size box shows how much drive capacity is available on the
selected logical drive when using the chosen RAID level. The left side of the slider
scale shows how much drive capacity is available for data storage, while the right
side indicates how much capacity is required for storing parity or mirrored
information. (RAID overhead is not needed for RAID 0.)
The default logical drive size first shown in this box is the maximum available for
your drive array. To create more than one logical drive on the array, reduce the
logical drive size by typing a smaller number in the scroll box. ACU allows you to
create up to 32 logical drives per array.