Server virtualization: Doing more with less

Tisdale agrees that VMware is feature-rich but says NewEnergy didn’t need many of its features. “We didn’t want to drive up cost and complexity by throwing in a lot of enhancements like load balancing and VMotion,” he says. “We just wanted to get the heat savings quickly and easily.”

 

saving $9,000 per month in power costs and huge amounts in network port and cabling costs,” says Dimitri Mundarain, Citrix’s manager of datacenter operations. Why Microsoft? “VMware’s ESX Server is more technically advanced and has a better management console but would be much more expensive in licensing and training costs. Our datacenter runs on Windows, and we like the fact that MS Virtual Server uses the same type of interface.”

For other organizations, virtualization is essential to extending the life of datacenters that are close to capacity. “We were running out of air- and power-conditioning capacity, which doesn’t scale and is very expensive to replace,” says Neal Tisdale, vice president of software development at NewEnergy Associates, a software and energy consulting company. NewEnergy used a combination of VMware GSX Server and Solaris Containers to consolidate its server hardware. The datacenter now runs 19 degrees cooler with no cooling upgrade, Tisdale says; and if the power fails, its batteries can keep it up for days, rather than hours, thanks to the reduced server power load.

Packing them in

Hand in hand with hardware consolidation comes increased utilization of current server resources. Before virtualization,

IT departments tended to limit each physical server to a single application and operating environment, as multiple applications tended to conflict with one another. The result was often server sprawl and inefficient use of server resources. Congdon says running multiple virtual operating environments on each server has increased server utilization at Capital One from an average of 30 percent to as much as 80 percent.

After monitoring his VMware environment for two weeks, NewEnergy’s Tisdale actually found that he could pack many more virtual servers onto a physical server than he originally thought — in the high teens and low twenties, rather than seven or nine. “Users generally overestimate how much they’re using a server, and the software vendors are conservative in estimating the memory needs of their applications,” he says.

Virtualization consumes its own server resources, of course, which can take its toll on application performance, but users point out that the overhead is offset by running applications on more powerful servers and taking advantage of VM portability. Congdon says general response times have improved now that his applications are sharing much more powerful server hardware.

When application performance declines due to an overbur-