Measure PUE in 2010! Why Measure Pue after I blog about it not being perfect, just last month?
Well, it is better than nothing. Actually it is more than that, it is the minimum insight into your data center.
Think of driving your car late at night in an unfamiliar location. You have no idea were the next open gas station will be:
How comfortable would you be without a gas gauge?
This auto analogy isn't too far off. Many corporate data centers have some monitoring system to let someone know :

• when the temperature gets too high
• when there is a water leak
  
• generator status
• UPS (battery) status

And then on the IT side there is often some monitoring system or other keeping track of most of the critical servers, storage, backups, firewalls, even critical applications. Often there are all kinds of graphs and analysis of these systems with trends and pretty graphs over time showing how much work has been done in the data center.
With all this often real time monitoring and trending, few corporate IT managers have no idea what their date centers PUE is for any point much less over time. Though PUE would be more closely related to MPG than a gas gauge. PUE gives you a base line. As an IT or facilities director, hopefully you are looking at reducing costs in this economy for 2010. The data used to calculate PUE can easily be used to calculate energy cost of the data center.
IT directors are used to showing costs of new projects amortized over time showing costs for:

• computers
• storage
• network
• cables
• support
• replacement hardware
• helpdesk
• even data center space

but usually not electricity. Some Directors are starting to include anticipated electric costs in the projections but most still don't consider it because the costs are not in their budget. Getting individual project electric cost projections can be much more difficult than measuring the data center as a whole. Planning a major new project for 2010, maybe some virtualization or new storage. Measure PUE before and after implementation.

Getting back to the gas gauge theme, my first cars were all older than me. They all pretty much had the same instruments in the dash: speedometer, gas gauge, odometer, and check engine light. My dad was a master mechanic from the navy and he had a term for that check engine light. He called it an "idiot light" because you were an idiot to drive with it on. If you don't measure PUE then you are relying on the "idiot light" which for many data centers comes in the form of high temperature alerts, and by then things are too late.

I have several vehicles now, from my motorcycle to a prius. Now that prius puts that gas gauge and "idiot light" to shame. There is a row of lights to tell me what is going on with the engine, check engine, change oil, change filter, tire pressure, rotate tires. Right in the middle of the car is a computer display showing instantaneous MPG, MPG for since last reset, a graph of MPG for the last 30 minutes, and a gas gauge.

This is the kind of information you want for your data center. A nice little graph showing how much energy is being used every 5 minutes. If you don't measure the PUE for you data center than it is worse than driving a 1955 Cadillac with a broken gas gauge (you do not want to guess how much gas you have in a car that gets less than 10 MPG).
Lets get started in 2010 by measuring the PUE.