HP Instant Capacity Version 10.x User Guide (5900-1581, March 2011)

NOTE: To defer the activation until the next reboot, add the -D option to the command. For more
information, see icapmodify(1M).
The icapmodify command allows you to activate additional cores with the -a option, or set the
total number of active cores with the -s option. For example, the icapmodify -a 2 command
activates two additional cores in a partition. The icapmodify -s 2 command sets the total
number of active cores in a partition to 2.
For details about software application implications when activating additional cores, see “Software
Application Considerations” (page 51).
Deactivating Cores
You can decrease processing capacity instantly on HP enterprise servers with the Instant Capacity
software (even on servers with sufficient usage rights for all cores to be active simultaneously). Any
number of active cores can be deactivated at any time, within the following partition constraints.
Core deactivation can be useful for load balancing cores in nPartitions (hard partitions) of Instant
Capacity systems.
Deactivating Cores in nPartitions
The software provides two types of core deactivation:
• Instant (icapmodify command’s default behavior) — deactivation occurs immediately.
• Deferred (icapmodify -D) — deactivation occurs after the next reboot of the partition.
Instant deactivation of cores occurs when the icapmodify command is used with the -d option
but without the -D option.
IMPORTANT: On OpenVMS Instant Capacity systems, HP strongly recommends that you deactivate
cores using the icapmodify or the ICAP SET command. The use of the STOP CPU command
on an Instant Capacity system can result in unintended consequences, such as a reactivation of
the core when an Instant Capacity reconciliation transaction is requested.
Deferred deactivation of cores occurs when the icapmodify command is used with both the -D
and -d options. With the deferred option (-D), core deactivation occurs after a reboot of the
partition. The scheduled timing of the reboot (and the core deactivation) can take place at a planned
time. For example, if you deactivate cores in deferred activation mode and schedule a partition
reboot to occur on the first day of the next month, the cores are deactivated at that time.
Since deferred deactivation does not immediately decrease the number of active cores, compliance
checking is not affected by deferred deactivation.
To deactivate one or more active cores, use theicapmodify command as root. For details, see
icapmodify(1M).
Partition Constraints
An nPartition must have a minimum of one active core for each active cell. Deactivation of cores
is limited by this rule. If the deactivation applies to a virtual partition, additional constraints might
apply, such as the minimum number of cores specified for the virtual partition.
Example Deactivation Session for Hardware-Partitionable Systems
Example 5 (page 44) shows how to deactivate an active core. At the beginning of this deactivation
session, there are a total of 4 cores in the partition; 3 cores are active and 1 is inactive. In this
example, 1 active core is deactivated, leaving the partition with 2 active cores and 2 inactive
cores. As with activation, you do not specify a particular core to be deactivated. You specify only
the number of cores to be deactivated.
Deactivating Cores 43