HP-UX Virtual Partitions Administrator Guide (includes A.05.09) (5900-2188, March 2012)

At this point, the 3 CPUs have already been added; you do not need to run vparmodify -a
cpu::3. If you do run vparmodify -a cpu::3, this will add 3 more CPUs to the virtual partition
(in addition to the 3 CPUs that were added with the icod_modify command).
Note that if you deactivate CPUs while in the vPars environment or in vPars mode using
icod_modify -d, this will un-assign those CPUS from the local virtual partition.
Assigning and Unassigning CPUs
While in the vPars environment, as long as the number of CPUs assigned to your virtual partitions
is less than or equal to the number of Intended Active CPUs, you can use vparmodify to add
CPUs to your virtual partitions. As long as the number of CPUs assigned to your virtual partitions
does not go below your specified vPars minimums (cpu:::[min]), you can delete CPUs from your
virtual partitions, regardless of the number of Intended Active.
Note that as stated above, while in the vPars environment or vPars mode, using icod_modify
-a assigns as well as activates those CPUs to the local virtual partition.
Intended Active Boundary
Using the iCAP software, the Intended Active number represents the number of licensed CPUs that
could be activated within an nPartition. To view the current Intended Active number, you can use
the iCAP command icod_stat. To change the Intended Active number, you can use the iCAP
command icod_modify.
While in the vPars environment (PA) or vPars mode (Integrity), the total number of CPUs assigned
to the virtual partitions cannot exceed Intended Active. This is true regardless of whether the virtual
partitions are up or down. If you encounter this situation, you may need to increase Intended Active
using icod_modify -a to activate and assign CPUs to your nPartition.
While in standalone (PA) or nPars (Integrity) mode, when the total number of CPUs assigned to
the virtual partitions exceeds the current Intended Active number for the nPartition, iCAP allows
this in the vPars database but displays a warning that the virtual partitions in the vPars database
will not boot. If you attempt to boot the vPars Monitor using this vPars database without increasing
Intended Active using the iCAP commands, the iCAP software will disallow this and shut down
any virtual partitions attempting to boot. You must reboot to standalone (PA) or nPars mode
(Integrity), fix the situation so that the total number of assigned CPUs is less than or equal to the
Intended Active number, and then reboot the vPars Monitor.
When assigning to an alternate and inactive vPars database, vPars and iCAP will allow the
assignments, but as in the above situation, if you attempt to boot this vPars database without
increasing the Intended Active number using the iCAP commands, the iCAP software will not allow
this and will shut down any virtual partitions attempting to boot. You must reboot to standalone
(PA-RISC) or nPars mode (Integrity), fix the situation so that the total number of assigned CPUs is
less than or equal to the Intended Active number, and then reboot the vPars Monitor.
CPU: Dual-Core Processors
With the PA-8800s and other dual-core processors, there are two CPUs per socket. (On a cell
board with four sockets, this allows 8 CPUs per cell board.) The CPUs that share the socket are
called sibling CPUs.
Splitting sibling CPUs across virtual partitions refers to assigning one sibling CPU to one partition
and assigning the other sibling CPU to a different virtual partition. No noticeable performance
degradation has been seen when splitting sibling CPUs. Due to items such as the larger L2 cache
size, there actually can be a small performance boost if the siblings are split such that one of the
virtual partitions has no workload. If you require consistently predictable performance, configure
the virtual partitions consistently; in other words, decide whether to split siblings or keep them
together, and maintain that policy across all virtual partitions.
CPU: Dual-Core Processors 221