Enterprises need monitoring tools to understand how power needs change as virtual servers move from one physical host to another. Before virtualization, a critical application might sit on a certain server in a certain rack, with two dedicated power feeds, Simonelli notes. With live migration tools, a VM could move from a server with fully redundant power and cooling supplies to a server with something less than that, so visibility into power and cooling is more important than ever. The ability to move virtual machines at will means "that technology is becoming disconnected from where you have appropriate power and cooling capacity," Simonelli says.
To support the high densities introduced by virtualization and other technologies such as blade servers, cooling must be brought close to the rack and server, Simonelli says. As it stands, cooling is already the biggest energy hog in the datacenter, with power wasted because of over-sized AC systems and temperatures set too low, he says.
While every datacenter has different needs, Simonelli says enterprises can learn something from the giant SuperNAP co-location datacenter in Las Vegas, a 407,000 square-foot building that relies heavily on APC equipment, such as NetShelter SX racks, thousands of rack-mounted power distribution units, and UPS power supplies.
While the site can support 60 megawatts, it's being built out in 20-megawatt chunks. "That means they can maximize the energy consumption, the efficiency of the datacenter as they scale. They're not powering the 60-megawatt site right away," Simonelli says.
One of the biggest mistakes is to over-size power capacity, in anticipation of future growth that may never come. Companies have to plan for where they think they will be a few years from now, but build out in smaller increments, he says.
"You have to have the floor space, and you have to have the capability of getting power from the utility," Simonelli says. "But if you're going to build out a one- or a five-megawatt datacenter, and you know that your first year of deployment is only going to be 100 kilowatts, get the space and make sure you have power from the utility for five megawatts but just build it out in 250 or 500 kilowatt chunks."