Power Capping To Average Power Consumption; Using Enclosure Dynamic Power Capping In Power Provisioning - HP Integrity NonStop NB54000c Introduction Manual

are not all the same, HP recommends using Insight Control to review the peak power consumption of each server to
ensure that the selected Dynamic Power Cap will not significantly limit its actual peak power consumption.

Power capping to average power consumption

An administrator can further increase provisioning capacity by capping the example group shown in Figure 11 at
the average power consumption: 1900 watts. Capping to average power consumption should not significantly
affect overall average computing throughput of servers running fairly uniform workloads. However, it may increase
latency during workload peaks or marginally affect the overall server performance in some applications.
The case shown in Table 6 reserves a 10 percent guardband for other factors (see "Providing a guardband for a
power capping group"). Even so, capping to average with basic Power Capping allows provisioning of over
60 percent more servers within a given cooling infrastructure.
Table 6. Power consumption for eight DL380 G5 servers when capping to average power consumption using basic Power
Capping
Description
Maximum power consumption for 8 ProLiant DL580 G5 servers
(based on HP Power Calculator)
Maximum power consumption when capping to average
Guardband
Savings in power capacity
Additional servers that can be provisioned within the same cooling infrastructure
Dynamic Power Capping will more significantly affect any workload transients exceeding the cap. Therefore, HP
recommends capping a server group supporting Dynamic Power Capping at the average power consumption only
in applications where peak transient performance is not a concern. Higher guardbands for the group might be
appropriate as well.

Using Enclosure Dynamic Power Capping in power provisioning

Dynamic Power Capping can control server power consumption quickly enough to prevent transient server power
demands that may trip circuit breakers in the data center. Using Enclosure Dynamic Power Capping, an
administrator can essentially cap the electrical provisioning for an enclosure by setting an enclosure power cap.
For example, consider an HP BladeSystem c7000 enclosure fully configured with 16 server blades. Provisioning the
power to the total of the HP 2250W power supplies' specification requires delivering 7836 watts to the enclosure.
You would typically use a single 30-amp 3-phase 208-volt circuit, which has a total capacity of 8640 watts.
However, if the enclosure's peak power consumption over time is less than 4000 watts, you can provision and
operate two full enclosures from the same circuit with no performance loss, if you cap both enclosures at 4000-watts
(Figure 12).
Power
3384 watts
1900 watts
190 watts
1294 watts
5
19