Cisco Cisco UCS C22 M3 Rack Server White Paper

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White Paper

Cisco UCS C-Series M4 Server Power
Management

August 25, 2014

Sriranjan Bose, Technical Leader, Cisco Data Center Group

Chitkala Sethuraman, Software Engineer, Cisco Data Center Group

Vikram Bodireddy, Software Engineer, Cisco Data Center Group

This white paper provides an overview of the features and best practices for the new
advanced power management capabilities available with Cisco UCS

C-Series M4

rack servers.

Introduction to Power Capping

Power capping provides the ability to limit the power consumption of a system, be it a blade server or a rack-mount
server, to some threshold that is less than or equal to the system’s maximum rated power. The feature typically

offers incremental benefits with the ability to scale a greater number of systems, as well as providing even better

control over power consumption.

There are two major types of power capping. Static power capping involves distributing a fixed budget of power

across multiple servers by calculating the individual system consumption using its rated or nameplate power rating.

For example, if the maximum power rating of a server is given as 340 watts (W) and a rack in a data center is

equipped with 10 servers, but the power available to the rack is only 3100W AC, the available power is sufficient to

supply an average of 300W per rack server. In this case, each server can be capped at a maximum of 300W to

avoid exceeding the capacity of the power supply. An obvious drawback of this approach is the inconsistency of

power ratings across rack servers. This rating depends on the configuration of the server, affected by the types of

DIMMs, CPUs, and adapters the system is equipped with. Another drawback is that the power consumption of the

systems in the rack may not be peaking at the same time. So the server power consumption will be capped even

when the overall power budget has not reached full capacity.