HP Surestore Disk Array 12h - And FC60, Advanced User'S Manual, Page: 305 / 466

Managing the Disk Array Using Array Manager 60
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Managing the Rebuild Process
If a disk fails, the disk array automatically begins the rebuild process the first time an I/O is
performed to the LUN, providing that there is a global hot spare available. If no global hot
spare is available, the rebuild will not occur until the failed disk has been replaced.
While a rebuild is in process, you can check its progress and change the rate at which the
rebuild occurs. A rebuild must be in process to perform either of these tasks.
Checking Rebuild Progress
To check the progress of a rebuild, type:
amdsp -r <ArrayID>
The progress of all rebuilds currently taking place on the disk array will be displayed.
Changing Rebuild Priority Settings
The rebuild process must compete with host I/Os for disk array resources. Two settings
allow you to control whether the rebuild process or host I/Os will have greater access to
these resources. These settings reflect how important the rebuild process is relative to I/O
activity on the LUN being rebuilt.
If you select settings that give higher priority to the rebuild process, it will complete sooner
but at the cost of lower I/O performance. Lower priority settings give precedence to host
I/Os, which may delay the completion of the rebuild. These settings are used only if host
I/Os are occurring during the rebuild.
To change the rebuild priority settings, type:
amutil -R <LUN> -f <freq> -a <amount> <ArrayID>
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freq identifies the rate at which the disk array attempts to execute rebuild commands.
Specified in tenths of a second, this value can be set to 1 to 50, or 0.1 seconds to 5.0
seconds. A low setting increases the frequency at which rebuild commands are issued,
giving higher priority to the rebuild, but reducing I/O performance. A high value reduces
the rebuild command frequency, giving higher priority to host I/Os. The default value for
this setting is 1, or 0.1 seconds.