HP ML150 HP Power Capping and Dynamic Power Capping for ProLiant servers techn - Page 21

Power capping to average power consumption An administrator can achieve additional increases in provisioning capacity by capping the group at the average power consumption level of 1900 watts. When applied to servers running fairly uniform workloads, capping to average power consumption should not significantly impact overall average computing throughput of the servers, although it may cause an increase in latency during workload peaks. In the case shown in Table 6, capping to average with basic Power Capping almost doubles the number of servers that can be provisioned within a given cooling infrastructure while only marginally impacting the overall server performance in this particular application Table 6. Power consumption for eight DL380 G5 servers when capping to average power consumption using basic Power Capping Description Power Maximum power consumption for 8 ProLiant DL580 G5 servers (based on HP Power Calculator) 3384 watts Maximum power consumption when capping to average 1900 watts Savings in power capacity 1484 watts Additional servers that can be provisioned within the same cooling infrastructure 6 Since Dynamic Power Capping will more significantly impact any workload transients exceeding the cap, a group of servers supporting Dynamic Power Capping should only be capped at the average power consumption in applications where peak transient performance is not a concern. 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 required 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, typically by using 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, then two full enclosures can be provisioned and operated from the same circuit with no performance loss, as long as both enclosures are capped at 4000-watts. This is illustrated in Figure 12. 21