HP Instant Capacity Version 10.x User Guide (762794-001, March 2014)

Figure 9 Partition premodification state: Three cells with 3 active and 1 inactive cores in each, and

3 expected inactive cores

Cell 1

A AA

Cell 2

A AA

Cell 3

A AA

Figure 10 Partition postmodification state: Unassigned Cell 3 (total of 8 active cores are set)

Cell 1

A A AA

Cell 2

A A AA

Figure 11 Postmodification state: Unassigned Cell 3 with 4 inactive cores, with usage rights available

for 1 additional core

Cell 3

Available

Usage Rights

IIII

When Cell 3 is unassigned from the partition, the number of intended active cores changes from

9 to 8 (because 8 is the total number of cores remaining in the partition). When the partition is

rebooted, a total of 8 cores are activated. Cell 3 becomes an unassigned cell with 4 inactive cores,

and (unused) usage rights are available for 1 additional core for the complex.

NOTE: If you intend to migrate a cell from one partition to another, you can control the number

of core usage rights available to the cell (in the new partition) by deactivating cores in the partition

you removed the cell from. By deactivating cores, you make core usage rights available to the

entire complex.

Balancing the distribution of I/O interrupts

When a core is deactivated online, the I/O interrupts that are assigned to it are migrated to the

remaining cores. When a core is activated online, HP-UX kernel never assigns any I/O interrupts

to the newly activated core. If core deactivations are followed by a large number of core activations,

I/O interrupts might be assigned to the specific cores. If the I/O load is too high, the response

time may increase and throughput may reduce due to this imbalance.

The daemon for balancing interrupts (intrbald) should be run in all the HP-UX nPartitions and

virtual partitions (A.04.x/A.05.x) to avoid the situation. Before starting the production, it is

recommended to set INTRBALD_STATE to enabled in /etc/rc.config.d/intrbaldconf

to run the daemon.

NOTE: Intrbald is available on HP-UX 11i v2 and HP-UX 11i v3. It has been provided as default

since HP-UX 11i v3 March 2008. PHCO_36079 is required for HP-UX 11i v2.

Software application considerations

Some software applications size themselves based on the number of available cores when the

application is started. If an application is running when an additional core is activated, the

Balancing the distribution of I/O interrupts 49