HP StorageWorks 1500cs Modular Smart Array - Manual (Page 54)

Using the Command Line Interface 54
• At the medium setting, rebuilding occurs for half of the time, and normal system operations occur for
the rest of the time.
• At the high setting, the rebuild takes precedence over all other system operations.
If the logical drive is part of an array that has an online spare, rebuilding begins automatically when
drive failure occurs. If the array does not have an online spare, rebuilding begins when the failed
physical drive is replaced.
Syntax:
<target> modify rp=high|medium|low
where <target> is a controller.
Example command:
=> ctrl slot=3 modify rp=high
Changing the Expand Priority setting
The Expand Priority setting determines the urgency with which the controller treats an internal command to
expand an array.
• At the low setting level, normal system operations take priority over an array expansion.
• At the medium setting, expansion occurs for half of the time, and normal system operations occur for
the rest of the time.
• At the high setting, the expansion takes precedence over all other system operations.
Syntax:
<target> modify ep=high|medium|low
where <target> is a controller.
Example command:
=> ctrl slot=3 modify ep=high
Changing the controller cache ratio
The controller cache ratio setting determines the amount of memory allocated to read and write
operations. Different types of applications have different optimum settings. You can change the ratio only
if the controller has a battery-backed cache (because only battery-backed cache can be used for write
cache) and if there are logical drives configured on the controller.
Syntax:
<target> modify cr=#/#|?
where <target> is a controller, and #/# is the cache ratio in the format read percentage/write
percentage.
Example command:
=> ctrl slot=3 modify cr=25/75
Changing the surface scan delay time
The setting for the surface scan delay determines the time interval for which a controller must be inactive
before a surface scan analysis is started on the physical drives that are connected to it.
Surface scan analysis is an automatic background process that ensures that you can recover data if a
drive failure occurs. The scanning process checks physical drives in fault-tolerant logical drives for bad
sectors, and in RAID 5 or RAID 6 (ADG) configurations, it also verifies the consistency of parity data.
Syntax: