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the enclosure and to create power caps for the individual server blades. It will then monitor and adjust the
individual server blade power caps based on their power demands.
Figure 9.
Setting a power cap for a group of enclosures in Insight Control
Using power capping in data center provisioning
Power capping is a tool to help IT organizations manage infrastructure size and costs in the data center. Setting a
power cap for a server or group of servers assures a data center manager that unexpected changes in workload or
environment will not cause servers to consume more than the specified amount of power.
Appropriate use of basic Power Capping in the data center lets administrators provision the cooling infrastructure at
an effective level. Effective provisioning meets cooling requirements associated with server power consumption at a
realistic application load, when having all servers running at full power is unrealistic. Alternatively, using basic
Power Capping to limit average server power consumption will allow operating more servers safely within a pre-
existing cooling infrastructure.
Dynamic Power Capping takes this one step further. Its ability to control server power consumption in real time
allows administrators to use power capping for planning and managing both their electrical provisioning and their
cooling infrastructure.
Choosing effective power caps
Setting an effective power cap involves determining the lowest value for the power cap that will still meet the power
requirements for a server or group of servers running their application workload. An effective power cap should
have no affect on server application performance but would reduce the required cooling and electrical provisioning
for the servers.
Administrators can use the HP Power Calculator Utility to estimate the maximum input power for a given server
configuration. This information provides a starting point for considering power caps. Once you have deployed an
application in a laboratory or in production, reporting features in Insight Control and iLO provide historical power
consumption data. You can use that data to refine the power cap selection to achieve specific power savings or
capacity planning targets.
Figure 10 shows the output from the HP Power Calculator utility for a ProLiant DL380 G5 server configured with two
Quad-Core Intel Xeon X5460 3.16-GHz processors, one 72-GB disk drive, and 8 GB of system memory. The results
