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With virtualization know-how under their belts, IT managers have begun to consider virtualization for remote and branch offices to reduce the number of servers in locations without a lot of IT staff. But while virtualizing servers in a data center is straightforward, questions about how best to virtualize branch offices -and which virtualization platform is best suited to the task -- persist.

The IT architect at a large financial services firm is exploring how to implement virtualization at four branch offices, each with several hundred users. A new location was recently outfitted with two VMware servers, which was a no-brainer. "It was a new site, a new building," said the IT architect, whose firm does not allow him to speak publicly about its IT infrastructure. "Other sites, you don't always have those opportunities."

Upping the infrastructure ante
At the other sites, finding the right combination of servers and storage has been tough. "I'm trying to find a cost model that works for virtualization in the field," he said. The problem? "It's not really a virtualization issue for us, it's a storage issue."

Specifically, the infrastructure architect is struggling to find networked storage required by a VMware deployment that provides good performance, sufficient availability, and -- here's the rub -- a reasonable price tag.

"You can always buy less expensive storage, but I want to provide a solution that's at the level of that they have today,"

he said -- namely, locally attached SAS (or serial-attached SCSI) drives. On the availability front, "if I go with single-controller storage and I lose a controller, I lose all the VMs [virtual machines]," he explained. But high-performance, dual-controller storage area network (SAN) arrays are out of reach, budget-wise. "It becomes a balancing act."

Licensing virtualization software, by comparison, is no big deal. The difference between VMware licenses are rounding errors compared with the cost of going from single controller to dual controller, from iSCSI to Fibre Channel, etc., he said.

For one administrator, the potential savings in deploying a lower-cost virtualization platform isn't worth it. "I want the same technology for every site. I don't want to have to support two hypervisors, and a lot of times the free offerings [e.g., ESXi free] aren't enough."

Indeed, this administrator wants to have his cake and eat it too: He wants the reduced overhead that comes from virtualizing servers but also the high availability and performance inherent in a cluster of virtualized hosts (for VMware High Availability and VMotion) and the attending SAN.

That raises the question of whether Microsoft can make inroads against VMware by positioning Hyper-V Server 2008 R2 as a low-cost alternative for branch office deployments.

On its website, Microsoft positions Hyper-V Server 2008 R2 as a technology suited for organizations that want to consolidate on a single physical server or that have low utilization infrastructure workloads, departmental applications and simple branch-office workloads." However, like with VMware, high availability and live migration both require expensive networked storage.

WAN optimization vendors get in the game
Some organizations tackle the branch-office problem with wide area network (WAN) optimization and caching technology from vendors such as Riverbed Technology, Citrix Systems Inc. and Blue Coat Systems Inc.. Their offerings allow applications and data previously hosted in a branch office to be brought back under the auspices of a central data center and accessed over a WAN.

WAN optimization vendors used to peddle a vision of a single server in the branch office, with all applications accessed over a network. That approach worked well for applications such as email, file servers, collaboration and Web-based applications, said Joe Skorupa, Gartner Inc.'s research vice president for networking and communications. SharePoint, in particular, is a prime target for WAN optimization, he said. "SharePoint spread the way swine flu was supposed to, and it does terribly over the WAN."

Remaining in the branch are "the servers that people forgot are there," Skorupa said, mainly core services such as DNS, DHCP and Active Directory that users want to access even if the network is down, as well as "one other app -- the application they can't live without." For instance, a remote law office will run a centralized billing application "because lawyers don't pick up the phone if they don't know if they can bill for it," and a doctor's office will run a patient scheduling application.

High powered hardware
WAN optimization vendors have traditionally offered their wares on a dedicated hardware appliance. But today's multicore servers are more than capable of running more than just WAN optimization. As such, Riverbed offers a virtualization option -- the so-called Riverbed Services Platform, or RSP, for its Steelhead appliances that allows users to run up to six virtual machines on a copy of the free VMware Server loaded on the appliance.

Another approach is to package WAN optimization or caching software as a virtual appliance that runs on a generic virtualization host such as VMware ESX or Citrix XenServer. Blue Coat and Citrix already offer this with their respective ProxySG and NetScaler VPX products, and Riverbed has committed to delivering a Steelhead virtual appliance this calendar year.

Which model is better depends on your perspective. Gary Middleton, a business development manager at Dimension Data, a global integrator headquartered in South Africa, said that the virtual appliance model "offers more flexibility -- it's running on a standard appliance that you can do more with." It also lets organizations source hardware from their preferred vendor. "Most companies like to standardize their hardware. The fewer types of hardware the better," Middleton said.

But going with the dedicated-Riverbed-appliance route has its benefits too, said Tom Becchetti, a Unix and storage engineer at a large Midwestern manufacturing firm that runs Riverbed Steelhead appliances at "hundreds" of remote offices. Before choosing Riverbed, the firm explored the option of deploying VMware servers in the branch to run core infrastructure services like file, print and Active Directory. But the Steelhead appliances "are cost-justified just because of the [smaller] size of the pipe that you need," he said.

Currently, Becchetti's firm is in the process of considering an upgrade to the Riverbed Service Platform, and whether or not to bring it in under the auspices of VMware vCenter. "Typically the applications you would run at smaller sites would be lightweight, and would still be an OK fit."

Let us know what you think about the story; email Alex Barrett, News Director at abarrett@techtarget.com, or follow @aebarrett on twitter.

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