Recent studies [16,12,11,15] have shown that the application
of DVFS on the CPU results in almost linear power-to-frequency
relationship for a server. The reason lies in the limited number
of states that can be set to the frequency and voltage of the CPU
and the fact that DVFS is not applied to other system components
apart from the CPU. Moreover, these studies have shown that on
average an idle server consumes approximately 70% of the power
consumed by the server running at the full CPU speed. This fact
justifies the technique of switching idle servers to the sleep mode
to reduce the total power consumption. Therefore, in this work we
use the power model defined in