Virtualization Heads Beyond Consolidation

The following case study is the first of our five-part series on the gains and pains of server virtualization. First up: Orchard Supply Hardware
Son paid an average of $5,000 per host for Orchard Supply's 13 hosts running VMware's EXS Server under vSphere 4, adding an expense of $65,000, but overall, he says the company's virtualized environment cost a total of $265,794 for hardware and software versus $1,119,750 for a similar, nonvirtualized infrastructure. Orchard Supply's total savings after 3-1/2 years of intensive virtualization: $853,956.

"Now we can spin up a standard server in 10 minutes instead of three to four weeks," Son says. "It's worked out really well. Virtualization has taken the guesswork and human error out of server configuration."

Son wanted greater availability for Orchard Supply's time and attendance scheduling application, as any of the company's 5,000 employees "needs to be able to punch in or request time off at any time," he says. "This is one of our highest-availability applications. It has to be up 100% of the time."

In the former environment, 100% uptime wasn't possible, as the different servers developed their unique glitches and a small data center operations staff struggled to keep everything running. In the virtualized environment, VMware's vSphere 4 with VMware Service Manager provides availability management mapped to ITIL standards. Son's team can manage 13 of 45 physical servers through a vCenter console in "a centralized, single-pane view" of VM operations and resources.

Uptime improved to 99.51% last year. This year, it was up to two months of continuous 99.75%, and Son thinks his team can eventually get the environment to four nines, a big improvement over the pre-virtualized data center (though no metrics are available).

Orchard Supply has experienced no VM failures on any host, says Son, who attributes the high uptime to the automated configuration of virtual server machines via vSphere 4 tools. Son's team defines server profiles, then VMs are configured only to those specifications. For example, not all of the company's Dell servers were bought at the same time, so Son's team identifies groups with like characteristics, then defines policies that govern what can be run on them. A database server needs to be both CPU- and I/O-intensive, and the team can assign database VMs to the physical servers that are the best matches.

Likewise, the live migration of VMs needs to occur between identical chipsets. Within the x86 instruction set, there are slight variations even within the same generation of chips--say, the Xeon line--and moving VMs between slightly dissimilar iterations risks failure. Under the vCenter console, a vMotion command is reviewed to make sure the operator is moving like to like. It will show an alert if the operator tries to do otherwise. Son has closely documented the nature of each server, including the physical CPU, and defined policies saying what can be moved where. That may mean less flexibility than he'd prefer, but it also means many fewer interruptions and alerts, he says.

Virtualization helps reliability and uptime in another major way, Son says. Virtualizing servers not only allows for those machines to be consolidated, he notes, but it also allows for network interfaces to be consolidated, as fewer cables are needed to tie a group of servers to the network.

At Orchard Supply, an average virtualized host has 11 network connections, with two redundant connections to the iSCSI SAN, a vMotion connection, two dedicated backup connections, two service console management network connections, and two connections allowing communications between VMs on the server. That means 143 cables need to be connected for the 13 virtualized hosts and 125 virtual servers.

In the pre-virtualization days, 125 standalone servers would require 375 cables. A single virtualized host, on the other hand, runs 20 to 30 servers, which share the cabling of network interface cards and host bus adapters to network switches. Fewer cables reduces the chance of any downtime resulting from a cable getting bumped or dislodged under more crowded conditions.

More significantly, Son's team is rapidly expanding business services without increasing the server count. The environment is experiencing less downtime, and it has room to expand. "We oversized our virtualized infrastructure," Son says. "We can grow without buying more hardware or software."

To a seasonal business like Orchard Supply, he says, "virtualization makes our data center suitable for a flexible, cyclical enterprise."

Next Up In Part 2: Roswell Park Cancer Research Institute

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