HP Instant Capacity (iCAP) manual Table A-1 Removing a Cell and Decreasing Inactive Cores

Implications of Removing a Cell from an Instant Capacity System

The Instant Capacity software tracks the expected number of inactive components (cores, cells, and memory) in a complex and knows the actual number of active and inactive components. The complex is in compliance if the actual number of inactive components meets or exceeds the expected number of inactive components.

The complex is out of compliance if the actual number of inactive components is less than the expected number of inactive components and no temporary capacity is available.

However, a complex can also get out of compliance if a cell is removed from the complex. For example, if a cell contains inactive cores that are contributing to compliance, and the cell is removed, there will be fewer inactive cores in the complex. This can result in the complex being out of compliance, and temporary capacity might begin to be debited.

For example, a complex contains 2 cells, with 2 partitions having 2 inactive and 2 active cores each. The Instant Capacity software expects the complex to have 4 inactive cores. If one of the cells (0) experiences a hardware problem, and you remove the cell, the complex is left with only 1 cell that contains 2 active and 2 inactive cores. The complex is now out of compliance because 4 inactive cores are expected to be in the complex, yet there are only 2 inactive cores.

Table A-1 Removing a Cell and Decreasing Inactive Cores

State	Partition (Cell) 0	Partition (Cell) 1	Notes
Before cell 0 is	2 active, 2 inactive	2 active, 2 inactive	4 inactive cores expected (in compliance)
removed
After cell 0 is	0 active, 0 inactive	2 active, 2 inactive	4 inactive cores expected (out of compliance)
removed

In this example, all cores in the removed cell are identified as active. This causes the complex to be out of compliance because the complex has 2 more active cores than it has core usage rights. This results in the complex consuming 2 hours of temporary capacity for each hour that the complex remains in this state. Deactivating another core from cell 1 decreases the amount of temporary capacity being consumed, but because at least 1 core must be active per active cell, this complex cannot remain in compliance unless of temporary capacity is used.

Note that removal of a cell, followed by a reboot of the affected partition, does not affect either the intended active number for the partition or the required number of inactive cores, which is determined by the overall availability of core usage rights across the complex. While the cell is absent, temporary capacity can be consumed if the number of inactive cores is less than the expected number of inactive cores. Having additional temporary capacity allows this system to remain in compliance even in the presence of a cell hardware failure.

Implications of Removing a Cell from an Instant Capacity System 197