Performance monitoring is just one aspect of virtual machine management. Other tasks include optimizing the mix of virtual machines that should reside on each physical server to achieve the best possible performance; automating virtual machine provisioning, load balancing, patch management, configuration management and fail-over; and enabling policy-based orchestration to automatically trigger the appropriate responses to events.

For some functions, such as patch management, existing tools work fine, says Paul Poppleton, a senior staff engineer at Qualcomm. In other areas, he says, "we're getting the best wins on the tools that take into account the fact that systems are virtualized."

Even organizations just starting virtual server projects can quickly run into management challenges. Once the decision is made to introduce virtual servers, the numbers can increase much more rapidly than expected because it becomes easier to procure new servers, says Poppleton. "Tack on 20 percent or 30 percent to what you planned on for growth, because it can really take off on you," he warns. Qualcomm has 1,280 VMware ESX Server virtual machines companywide that run a mix of Windows and Linux. About 850 virtual machines are running in Qualcomm's data center, with each physical server hosting an average of 10 virtual machines.

Even fine-tuning the performance for as few as 10 virtual machines can be a challenge. "One place where we've had trouble is trying to manage the resources on a single physical host," says Poppleton. VMware Inc.'s VirtualCenter 2 management software, which Qualcomm is beta-testing, should help with that, he says. The software is expected to ship in the first half of this year.

Finding the right tool