Server virtualisation: doing more with less (part 1)

Virtualisation has gone mainstream. Given the technology’s upside, it’s easy to see why.


This is part one of a two part article. The second part is here.

Virtualisation has gone mainstream. According to The Yankee Group’s 2006 Global Server Virtualisation Survey of 750 businesses, 62 per cent of respondents said they already had a virtualisation solution in place or were in the process of migrating to one. Only four per cent did not have plans to tap server virtualisation.

Given the technology’s upside, it’s easy to see why. Server virtualisation divides a physical server into multiple virtual machines, each of which can run its own isolated operating environment and applications. That means less hardware, reduced power and cooling costs, and extended data centre life. The ability to provision a new server simply by loading a virtualised image onto existing hardware not only saves IT management budget, it makes the business more agile.

Make no mistake; commodity server virtualisation is a relatively young technology. The market offers multiple solutions but few standards. Consensus among customers is that it works as advertised and is not difficult to implement, but efficient management and migration remain ongoing challenges. Nor is virtualisation appropriate for every application. Applications that hog I/O and memory resources, such as large database deployments and Microsoft Exchange, often are not good candidates for sharing server hardware with other applications, even in a virtual environment.

Customers that have taken the plunge are typically in the early phases of virtualised infrastructure: After initial testing, applications are virtualised gradually as servers are retired, applications are upgraded, or IT moves toward a service-delivery model. Despite a cautious start, however, the common theme among these customers is great enthusiasm for the genuine benefits virtualisation can bring.

A lot less hardware

One of the key incentives driving the market for virtualisation is a desire to reduce costs associated with server hardware, both for limiting new purchases and reducing the total portfolio of equipment in the data centre. For Capital One, a diversified global financial services company, virtualisation provides a key component of a three-year IT consolidation strategy and transformation to an on-demand service delivery organisation. This transformation is well into its second year.

“In the past, our businesses owned their server hardware and applications and had them configured to their individual specific requirements,” says Lee Congdon, managing vice president of corporate technology at Capital One. “The result was that we ended up with everything, including Unisys, Tandems, Suns, and AS/400s — you name it. On the software side, we were running Novell NetWare, old versions of [Windows] NT, and Windows 2000.”

To tame this unwieldy environment, Capital One began using VMware ESX Server to pack multiple server environments on fewer, more powerful physical servers. Rather than dedicating servers to individual business units, business users are increasingly assigned smaller shares of more powerful processors. “We currently have about 150 server instances running on 17 physical servers,” Congdon says. And rather than giving each business its own applications, Capital One has consolidated to five IT-approved platforms. The business units simply buy services, such as knowledge or content management, and often don’t even know what platform they’re using.

Similarly, Citrix is in the early stages of consolidating 15 racks of 200 out-of-warranty servers to just two racks, or a total of 10 HP ProLiant DL585 four-way, dual-core Opteron servers, using Microsoft Virtual Server 2005 R2. “We’ll be saving US$9,000 per month in power costs and huge amounts in network port and cabling costs,” says Dimitri Mundarain, Citrix’s manager of data centre operations. Why Microsoft? “VMware’s ESX Server is more technically advanced and has a better management console but would be much more expensive in licensing and training costs. Our data centre runs on Windows, and we like the fact that MS Virtual Server uses the same type of interface.”

For other organisations, virtualisation is essential to extending the life of data centres that are close to capacity. “We were running out of air- and power-conditioning capacity, which doesn’t scale and is very expensive to replace,” says Neal Tisdale, vice president of software development at NewEnergy Associates, a software and energy consulting company. NewEnergy used a combination of VMware GSX Server and Solaris Containers to consolidate its server hardware. The data centre now runs 19 degrees cooler with no cooling upgrade, Tisdale says; and if the power fails, its batteries can keep it up for days, rather than hours, thanks to the reduced server power load.

Tisdale agrees that VMware is feature-rich but says NewEnergy didn’t need many of its features. “We didn’t want to drive up cost and complexity by throwing in a lot of enhancements like load balancing and VMotion,” he says. “We just wanted to get the heat savings quickly and easily.”

Packing them in

Hand in hand with hardware consolidation comes increased utilisation of current server resources. Before virtualisation, IT departments tended to limit each physical server to a single application and operating environment, as multiple applications tended to conflict with one another. The result was often server sprawl and inefficient use of server resources. Congdon says running multiple virtual operating environments on each server has increased server utilisation at Capital One from an average of 30 per cent to as much as 80 per cent.

After monitoring his VMware environment for two weeks, NewEnergy’s Tisdale actually found that he could pack many more virtual servers onto a physical server than he originally thought -- in the high teens and low twenties, rather than seven or nine. “Users generally overestimate how much they’re using a server, and the software vendors are conservative in estimating the memory needs of their applications,” he says.

Virtualisation consumes its own server resources, of course, which can take its toll on application performance, but users point out that the overhead is offset by running applications on more powerful servers and taking advantage of VM portability. Congdon says general response times have improved now that his applications are sharing much more powerful server hardware.

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