Specifications

116 IBM Power 770 and 780 Technical Overview and Introduction
temperature and assumes a high-altitude environment. When a power savings setting is
enforced (either Power Energy Saver Mode or Dynamic Power Saver Mode), fan speed
will vary based on power consumption, ambient temperature, and altitude available.
System altitude can be set in IBM Director Active Energy Manager. If no altitude is set, the
system will assume a default value of 350 meters above sea level.
򐂰 Processor folding
Processor folding is a consolidation technique that dynamically adjusts, over the short
term, the number of processors available for dispatch to match the number of processors
demanded by the workload. As the workload increases, the number of processors made
available increases. As the workload decreases, the number of processors made
available decreases. Processor folding increases energy savings during periods of low to
moderate workload because unavailable processors remain in low-power idle states (nap
or sleep) longer.
򐂰 EnergyScale for I/O
IBM POWER7 processor-based systems automatically power off hot pluggable PCI
adapter slots that are empty or not being used. System firmware automatically scans all
pluggable PCI slots at regular intervals, looking for those that meet the criteria for being
not in use and powering them off. This support is available for all POWER7
processor-based servers and the expansion units that they support.
򐂰 Server power down
If overall data center processor utilization is low, workloads can be consolidated on fewer
numbers of servers so that some servers can be turned off completely. It makes sense to
do this when there will be long periods of low utilization, such as weekends. AEM provides
information, such as the power that will be saved and the time it will take to bring a server
back online, that can be used to help make the decision to consolidate and power off. As
with many of the features available in IBM Systems Director and Active Energy Manager,
this function is scriptable and can be automated.
򐂰 Partition power management
Available with Active Energy Manager 4.3.1 or later, and POWER7 systems with the 730
firmware release or later, is the capability to set a power savings mode for partitions or the
system processor pool. As in the system-level power savings modes, the per-partition
power savings modes can be used to achieve a balance between the power consumption
and the performance of a partition. Only partitions that have dedicated processing units
can have a unique power savings setting. Partitions that run in shared processing mode
will have a common power savings setting, which is that of the system processor pool.
This is because processing unit fractions cannot be power- managed.
As in the case of system-level power savings, two Dynamic Power Saver options are
offered:
– Favor partition performance
– Favor partition power savings
The user must configure this setting from Active Energy Manager. When dynamic power
saver is enabled in either mode, system firmware continuously monitors the performance
and utilization of each of the computer's POWER7 processor cores that belong to the
partition. Based on this utilization and performance data, the firmware will dynamically
adjust the processor frequency and voltage, reacting within milliseconds to adjust
workload performance and also deliver power savings when the partition is under-utilized.
In addition to the two dynamic power saver options, the customer can select to have no
power savings on a given partition. This option will leave the processor cores assigned to
the partition running at their nominal frequencies and voltages.