HP ProLiant DL280 HP Power Capping and HP Dynamic Power Capping for ProLiant s - Page 18

which is high in the dynamic range of the servers. So the effects of configuration and environmental changes are ignored. 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, administrators could use the 3116-watt power cap to manage electrical provisioning rather than provisioning to the faceplate value of the power supply. Table 5 illustrates how many more servers the same circuit could power under the 3116-watt power cap. Derating the faceplate value by 20 percent requires 7760 watts. This example reserves a 10 percent guardband for other factors (see "Providing a guardband for a power capping group"). With Dynamic Power Capping applied, the same circuit can support over 10 more servers, if all 10 have the same power cap 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 Guardband 312 watts Savings in power capacity 4332 watts Additional servers that can be provisioned within same 7760 watts using Dynamic Power Capping when capping to peak 10.1 It is important to understand this: Capping to peak based on the power consumption graph for a server group is actually capping to the peak of the total power consumptions of servers in the group. It assumes that all the servers in the group consume the same amount of power. This would not be true under these conditions: • If the servers were configured differently • If workloads on individual servers peaked at different times • If workloads varied significantly from server to server If all servers in the group did not consume the same amount of power, the cap in this example would have an adverse affect on server performance, especially if they support Dynamic Power Capping. If the servers in a group 18