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

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 exists.
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 on the complex. This may result in the complex being
out of compliance and temporary capacity may begin to be debited.
Example A-1 Removing a Cell and Decreasing the Actual Number of Inactive Cores
For example, a complex contains two cells, with two partitions having two inactive and two
active cores each. The Instant Capacity software expects the complex to have four inactive cores.
If one of the cells (0) experiences a hardware problem, and you remove the cell, the complex is
left with only one cell that contains two active and two inactive cores. The complex is now out
of compliance because four inactive cores are expected to be in the complex, yet there are only
two inactive cores.
Table A-1 Removing a Cell — Decrease Inactive Cores
NotesPartition (Cell) 1Partition (Cell) 0State
4 inactive cores expected (in compliance)2 active, 2 inactive2 active, 2 inactiveBefore Cell 0 is
Removed
4 inactive cores expected (out of compliance)2 active, 2 inactive0 active, 0 inactiveAfter Cell 0 is
Removed
In the above example, all cores in the removed cell are assumed to be active. This causes the
complex to be out of compliance as the complex has two more active cores than it has core usage
rights. This results in the complex consuming two 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 since at least one core must be active per active cell,
this complex cannot remain in compliance except through the use of temporary capacity.
Note that removal of a cell, followed by a reboot of the affected partition, does not affect 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. During the period
when the cell is absent, temporary capacity may be consumed if the number of inactive cores is
less than the expected number of inactive cores. Having additional Temporary Instant 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 175