Enterprise efforts to consolidate data centres and install virtualisation software are taking a big bite out of the number of power hungry application and storage servers required to support enterprise data. But after taking this critical first step, what else can you do to boost efficiency?

You can move from hatchet to scalpel (to borrow a metaphor from President Obama). In this instance, the reference means that once you've minimised your number of power sucking devices, it's time to precisely monitor and measure data centre environmental metrics, down to the nitty-gritty rack level, so that you know exactly what adjustments are needed to optimise efficiency.

These metrics, of course, are electrical power, heat, airflow, cooling, temperature, humidity and pressure levels. Having visibility into them on a device by device basis, a scarce capability today, reveals the degree to which they are in sync with each equipment manufacturer's recommended specifications for optimal operation.

 'It's hard to improve power and cooling efficiency if you don't know where the waste is in the first place," says Nik Simpson, senior analyst in Burton Group's data centre strategies practice.

Let's face it: it's far easier and less expensive to mount wireless sensors than wired ones. Not needing cabling lets sensors live in many more places, so you can see a more complete and fine grained lay of the land and make precise, appropriate adjustments. Wireless data centre sensors, sensor networks and associated monitoring and management applications, available from companies such as SynapSense and Arch Rock, are starting to enable these capabilities and could kick off an evolved approach to data center energy management.

"The smart grid is moving into the data centre, and it is wireless instruments making this possible," asserts Peter Van Deventer, CEO at SynapSense. He estimates that the cost of a wireless sensor is 10 to 20 times less than that of a wired sensor once you figure in the installation cost.

Because of cabling complexities, costs and the need for pricey data centre 10Gbps ports for sensor communication, wired sensors tend to be installed in very few locations. In fact, sometimes sensors are only in the computer room air handler (CRAH). Though some helpful tabulations and assumptions can be made from this data, they don't show the entire efficiency picture.

There are also useful sensor capabilities built directly into some equipment, such as Cisco's Energywise solution for monitoring the power levels of Cisco network connected devices.

One drawback with embedded sensors, though, is that they usually feed measurement data into each manufacturer's own management system, making it complex to correlate, Simpson notes.

The emergence of wireless sensor applications aimed specifically at gathering real time statistics in many places throughout the data centre should ease the task, though. The applications help maintain compliance with industry standards for Power Usage Effectiveness and Data Center Infrastructure Efficiency. SynapSense also automates some adjustments for optimisation.