Grid middleware vendor Appistry has launched a software module that automatically powers down servers when they are not needed by applications, thus saving energy.

The company's Enterprise Application Fabric (EAF) virtualises applications enabled with Appistry middleware across x86 servers. The new EnergySaver module lets administrators define policies that establish acceptable workload levels and power turn off computers when application use is low. When additional capacity is required, EnergySaver policies reactivate them.

EAF is used best in power-hungry, transaction-intensive environments. Because applications are decoupled from the grid of servers on which they run, energy can be saved by powering off servers when they are not needed. Additionally, EAF contains load-balancing and workload management capabilities. It provides high availability by replicating the state of a request to multiple places, so if a machine goes down, the request can be executed on another machine in the grid.

One customer, GeoEye of St Louis, is getting ready to deploy EnergySaver. GeoEye collects satellite imagery for the Department of Defense and other customers. Ray Helmering, vice president of product engineering at GeoEye, says that with EnergySaver he can set policies to shut down servers when the output of the satellites varies because of geographical position or meteorological conditions.

"We have variations in our processing schedule depending on the operations of our satellites," he says. "As imagery comes in, we need the processing power, but as there are slower times, we'll be able to save on energy. We don't know the actual impact yet of energy savings, but initial review says that this feature could be very important to us."

GeoEye develops its imaging application in-house and grid-enables it with an Appistry wrapper that allows its operations to be parallelised across the grid. This application requires huge amounts of computations and a large number of processors to run. Helmering's Appistry implementation, for instance, requires 50 dual-core x86 servers.

Analysts are encouraged with Appistry's efforts to consume less power in the datacentre.

"The principle that Appistry is addressing is going to be really important," says Simon Mingay, an analyst for Gartner in Egham, UK. "Most datacentres have the opportunity to alter the power status of the storage and servers in their infrastructure when that capacity is not required. In datacentres, you run everything 24/7 and everyone is incented (sic) to keep things that way, which in a world where energy costs are not important, is perfectly fine. In a more energy-conscious world that becomes more questionable."

Mingay says that many organisations have approached the idea of energy consumption through use of job-scheduling software, such as Sun's N1 Grid Engineer or CA's Unicenter Autosys Job Manager, which allows applications to run when conditions are optimal for them.

The downside of EnergySaver, according to Mingay, is that it has to be deployed on Appistry-enable applications. "We are going to see more of this technology, but right now applications need to modified to work in the Appistry environment. That renders it generally inapplicable."

Appistry was founded in 2001 and is focused on data-intensive intelligence agencies, oil and gas and logistics organisation.