The goal is to set benchmarks that help customers design virtual deployments that mix call-center and business applications on the same hosts and allow for live migration without risking such disturbances.
"We want to show them those contact-center applications that mix well with business applications," Sumner says, so customers maximize use of server resources and have flexibility about where applications can reside.
On the fly
Virtual environments can create new virtual machines on the fly to address performance dips, but this live migration can cause separate problems, Sumner says. "There can be as much as a five-second disruption. If you're switching voice, that's fairly significant for us to deal with," he says. So again he steers clear of live migration for time-sensitive applications.
In any case, live migration characteristics vary from vendor to vendor of virtualization platforms, and businesses need to know about the differences. "Be aware of what their live migration characteristics are and design around them," says Chris Wolf, an analyst with the Burton Group. "That might result in more VMs that average a smaller load versus, say, fewer VMs that run a higher concurrent load."
Live migration can result in proliferation of virtual machines, which in turn creates more challenges, says Francois Richard, the director of infrastructure engineering at Nuance Software, which makes speech-recognition software used in contact centers. Monitoring should be segmented so like applications can be viewed at once. For example, if speech-recognition software is located on multiple virtual machines on multiple physical hosts, monitoring should be set up to view all those instances at once, he says.
Some contact-center delays can be pinned on the hardware used to support the virtual machines rather than on the software, says Wolf. Converting virtual-machine demands for CPU, memory or I/O capacity creates an overhead as these virtual demands are translated into the use of physical resources. These translations take time that can cause delays in applications that require frequent updates to these page tables, Wolf says.
AMD has developed chips to handle these translations more quickly in hardware, and Intel is close behind, he says. So businesses should consider these chips when choosing hardware on which to run contact-center virtual machines.
"In the past I've seen organizations blame latency issues on network or storage I/O when in fact it's directly related to physical memory latency," Wolf says. "Businesses have been really afraid of the latency issues and of being able to do virtualization on a large scale, but with this hardware I see more of them looking to go in that direction in 2009."