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IBM Power 720 and 740 Technical Overview and Introduction
2.13 Energy management
The Power 720 and 740 servers are designed with features to help clients become more
energy efficient. The IBM Systems Director Active Energy Manager uses EnergyScale
technology, enabling advanced energy management features to dramatically and dynamically
conserve power and further improve energy efficiency. Intelligent Energy optimization
capabilities enable the processor to operate at a higher frequency for increased
performance and performance per watt or dramatically reduce frequency to save energy.
Certain configurations of the Power 740 server are ENERY STAR qualified:
http://www.ibm.com/systems/hardware/energy_star/power.html
2.13.1 IBM EnergyScale technology
IBM EnergyScale technology provides functions to help the user understand and dynamically
optimize the processor performance versus processor energy consumption, and system
workload, to control IBM Power Systems power and cooling usage.
On POWER7 or processor-based systems, the thermal power management
device (TPMD) card is responsible for collecting the data from all system components,
changing operational parameters in components, and interacting with the IBM Systems
Director Active Energy Manager (an IBM Systems Director plug-in) for energy management
and control.
IBM EnergyScale makes use of power and thermal information collected from the system to
implement policies that can lead to better performance or better energy utilization. IBM
EnergyScale has the following features:
Power trending
EnergyScale provides continuous collection of real-time server energy consumption. It
enables administrators to predict power consumption across their infrastructure and to
react to business and processing needs. For example, administrators can use such
information to predict data center energy consumption at various times of the day, week,
or month.
Thermal reporting
IBM Director Active Energy Manager can display measured ambient temperature and
calculated exhaust heat index temperature. This information can help identify data center
hot spots that need attention. See Figure 2-38 on page 109 for an example.
Power saver mode
Power saver mode lowers the processor frequency and voltage on a fixed amount,
reducing the energy consumption of the system while still delivering predictable
performance. This percentage is predetermined to be within a safe operating limit and
is not configurable by the user. The server is designed for a fixed frequency drop of almost
50% down from nominal frequency (the actual value depends on the server type and
configuration).
Power saver mode is not supported during boot or reboot, although it is a persistent
condition that will be sustained after the boot when the system starts executing
instructions.
Dynamic power saver mode
Dynamic power saver mode varies processor frequency and voltage based on the
utilization of the POWER7 or processors. Processor frequency and utilization
