Integrated Dell Remote Access Controller 8 Version 2.70.70.70 User’s Guide

Power capping in Blade servers

Before a blade server in a PowerEdge M1000e or PowerEdge VRTX chassis powers up, iDRAC provides CMC with its power requirements. It is higher than the actual power that the blade can consume and is calculated based on limited hardware inventory information. It may request that a smaller power range after the server is powered up based on the actual power consumed by the server. If the power consumption increases over time and if the server is consuming power near its maximum allocation, iDRAC may request an increase of the maximum potential power consumption thus increasing the power envelope. iDRAC only increases its maximum potential power consumption request to CMC. It does not request for a lesser minimum potential power if the consumption decreases. iDRAC continues to request for more power if the power consumption exceeds the power allocated by CMC.

After, the system is powered on and initialized, iDRAC calculates a new power requirement based on the actual blade configuration. The blade stays powered on even if the CMC fails to allocate new power request.

CMC reclaims any unused power from lower priority servers and then allocates the reclaimed power to a higher priority infrastructure module or a server.

If there is not enough power allocated, the blade server does not power on. If the blade has been allocated enough power, the iDRAC turns on the system power.