HP Instant Capacity User's Guide for Versions 8.x

Deactivating Cores
Deactivating Cores in nPartitions
You have the ability to decrease processing capacity instantly on HP enterprise servers with the
Instant Capacity software (even on servers with sufficient usage rights such that all cores can be
simultaneously active). Any number of active cores can be deactivated at any time, within the
partition constraints listed below. Core deactivation can be useful for load balancing cores in
nPartitions (hard partitions) of Instant Capacity systems. See “Instant Capacity Integration with
Virtual Partitions (HP-UX only)” (page 179) for details about deactivating cores in virtual partitions.
The software provides two types of core deactivation:
Instant (icapmodify command’s default behavior) — the deactivation occurs immediately
Deferred (icapmodify command’s -D option) the deactivation occurs after the next reboot
of the partition
Instant deactivation of cores occurs when the icapmodify command is used with the -d option,
and the -D option is not specified.
IMPORTANT: On OpenVMS iCAP 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
iCAP system may 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 specified. 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 a deferred deactivation does not immediately decrease the number of active cores,
compliance checking is not affected by a deferred deactivation.
To deactivate one or more active cores, use theicapmodify command as root. See the HP-UX
manpage icapmodify(1M) for details.
NOTE: Instant Capacity will always produce usage rights from unused capacity before producing
usage rights by deactivating cores.
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 may
apply, such as the minimum number of cores specified for the virtual partition.
Deactivation Example Session for Hardware-partitionable Systems
The following example shows you 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
a number of cores to be deactivated.
Deactivating Cores 61