Data Center Management must include continuous real-time monitoring.
I spend a great deal of time talking about data center efficiency and the technologies available to assist in driving efficiency up. Additionally a great deal of my time is spent discussing how to determine success in the process(es). What I find is that there is still a fundamental missing appreciation for the need for 'continuous' real-time monitoring to measure success using industry norms such as PUE, DCIE, TCE and SWaP. I can't tell you how many times someone will tell me that their PUE is a given value, and look at me oddly when I ask 'WHEN was that?'. It would be like me saying 'I remember that I was hungry sometime this year'. The first response would clearly be 'WHEN was that?'
Most best practice guidelines and organizations involved here, (such as The Green Grid, and ITIL) are very clear that the improvement process must be continuous, and therefore the monitoring in support of that goal must also be. PUE for instance WILL vary from moment to moment based upon time of day and day of year. It is greatly affected by IT loads AND the weather for example. PUE therefore needs to be a running figure, and ideally monitored regularly enough that the Business IT folks can detremine trending and other impacts of new business applications, infrastructure investments, and operational changes as they affect the bottom line.
Monitoring technologies should be deployed that are installed permanently. In general, 'more is better' for data center monitoring. The more meters, values, sensors and instrumentation you can find and monitor, the more likely you'll have the raw information needed to analyze the data center's performance. Remember, PUE is just ONE KPI that has enough backing to be considered an indicator of success or progress. There surely will be many other KPIs determined internally which will require various sets of raw data points. More *IS* better!
We all get hungry every 4 hours, why would we monitor our precious data centers any less often?