HP ML150 HP Power Capping and Dynamic Power Capping for ProLiant servers techn - Page 20

Calculator Utility shows for this configuration. Table 4 shows a summary of the power consumption and capacity savings for the server group. Table 4. Power consumption for eight DL380 G5 servers when capping to peak power consumption using basic Power Capping Description Maximum possible power consumption for 8 DL380 G5 servers (based on HP Power Calculator) Maximum power consumption when capping to peak Power 3384 watts 3116 watts Savings in power capacity 268 watts Additional servers that can be provisioned within the same cooling infrastructure 0.7 If all eight servers supported Dynamic Power Capping, the 3116 watt power cap could also be used to manage electrical provisioning. Using traditional guidelines, these eight servers would require 7760 watts of provisioned power to support them. As Table 5 shows, if Dynamic Power Capping is applied the same circuit can support over 11 more servers, assuming all are capped at the same power levels as the first eight servers. Table 5. Power provisioning for eight DL380 G5 servers when capping to peak power consumption using Dynamic Power Capping Description Traditional input power provisioning for 8 DL380 G5 servers (1217 input VA at 208 volts de-rated by 20 percent) Maximum power consumption when capping to peak Power 7760 watts (970 x 8) 3116 watts Savings in power capacity 4645 watts Additional servers that can be provisioned within same 7760 watts using Dynamic Power Capping when capping to peak 11.9 When capping to peak based on the power consumption graph for a group of servers, it is important to understand that we are actually capping to the peak of the sum of the power consumptions of the servers in the group and then distributing that group cap as individual power caps for each server. It is possible, especially if workloads on individual servers are peaking at different times or if workloads vary significantly from server to server, that the individual power caps created for one or more servers in the group may be lower than the individual peak power consumptions for those servers. This will have an adverse affect on the performance of those servers, especially if they support Dynamic Power Capping, since its faster monitoring will have greater impact on limiting transient peaks. HP recommends that administrators using Dynamic Power Capping review the peak power consumption of each server through IPM to ensure that the selected power cap for the server does not significantly limit its actual peak power consumption. 20