Given that it is important to measure power usage and correlate it to application performance, how do you measure the power?

We use 2 different methods - one for rack-mounted servers and another for blade servers.  The rack-mounted servers do not provide power meters, so we bought a power meter.  We plug the server into the power meter, so we are measuring the total power used.  Then, with a simple PC interface, we allow the application user on the server to obtain continuous power data which is easy to correlate with the applications. 

This is easy for the users, but it requires planning and logistics and some work by our system managers, to connect the meter to the right server at the right time.

We often want to measure the power of a cluster running one HPC application in parallel, and it is usually sufficient to measure the power of any one server in the cluster running the application.

It is easier to measure power on an HP blade enclosure, since the enclosure contains power measurement capability and provides this data in a usable way.  The available data includes the total enclosure power and also the power used by each blade server and each fan in the enclosure.  We integrated this information with the Platform Computing LSF job scheduler.  Now, users of our blade servers submit their jobs via LSF and automatically receive their power usage data as part of the job.

Next week, I expect to post a message from the SC08 conference.