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

Configuring an Array
Compaq Smart Array 5i Plus Controller and Battery Backed Write Cache Enabler User Guide 7-11
COMPAQ CONFIDENTIAL
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 settings that you use for Rebuild Priority and Expand Priority will not affect
the performance of an idle system. However, they will affect performance on a busy
system:
• On the High settings, the controller will give preference to the rebuild or
expansion process over normal I/O operations.
• On the Low settings, the controller will rebuild or expand only when the
controller is idle. However, this setting leaves the array vulnerable to drive
failure for a longer time than the High setting.
The Accelerator Ratio setting determines the amount of memory allocated to the
read and write caches. Some applications may perform better with a larger write
cache; others may perform better with a larger read cache. If your controller does not
have a battery backed array accelerator, only read cache will be available (the ratio
will always be 100% Read / 0% Write).
NOTE: If you optimize the Accelerator Ratio setting, you may also want to change the Stripe
Size setting. See the “Create Logical Drive Screen” section and Table 7-2 and Table 7-3 for
details.
Create Drive Array Screen
To display this screen, click Create Array in the Controller box (Figure 7-6) on the
ACU Main Configuration screen. The left panel of the Create Drive Array screen
shows all drives that are attached to the controller that was selected on the ACU
Main Configuration screen.