How Server Virtualization Tools Can Balance Data Center Loads

Fri, June 15, 2007 — CIO — For Monster.com, the initial benefits of virtualization in the data center were easy to see: With 500 virtual machines (VMs) running on 17 servers, Monster cut power and hardware spending and improved efficiency, since virtual machines can be deployed much faster than standard hardware. But as Monster’s virtual environment got big, and got big fast, management problems arose. The worst one: The company didn’t have enough visibility into which applications were competing with each other across storage and server resources—and this was affecting IT’s ability to meet service-level goals, says Pete King, manager of monitoring and analysis at Monster.

“We ran into a lot of contention,” says King.

So King turned to BalancePoint, a workload balancing and applications service-level-management tool from startup Akorri, to ease the pain. BalancePoint shows when and why a particular VM is not performing up to standard, and based on that data, King can redistribute the load to increase efficiency. It analyzes performance on the VMware side and storage area network side to avoid virtual fights for resources.

Now that Monster has been using BalancePoint for a little more than a year, “there’s less trial and error,” says Paul Neilson, senior vice president of technology services. Monster no longer has to move VMs around based on “intuition,” he adds.

Almost everyone using server virtualization will bump up against one or more of the common management problems, including workload balancing, “VM sprawl” and disaster recovery plan complications, says IDC analyst Stephen Elliot. Tools from VMware and a growing number of third-party vendors can help.

Keep Your Balance
Workload balancing can be a tough problem to get your arms around. One key benefit of virtual machines is the ability to move them easily from one physical server to another. Problem is, it’s hard to know how many VMs on a particular server are too many—since the answer may depend on the applications, plus factors like memory and attached storage. In an environment where critical applications compete for the same server, it becomes difficult to see which applications are contending with each other, and this affects a company’s ability to prevent slowdowns.

For Monster, managing this challenge required multiple tools, a situation that’s not uncommon. Monster uses Akorri’s BalancePoint to augment the capabilities of VMware’s two main management products, VMotion (which increases hardware utilization by migrating VMs on failing or underperforming servers to another machine) and Distributed Resource Scheduler (which couples with VMotion to allocate resources to high-priority VMs based on preestablished rules you set).