Having enjoyed the relatively easy cost benefits of server virtualisation, many organisations look to repeat the trick with the desktop estate. But the financial benefits of desktop virtualisation are not as simple as increasing the utilisation rate of servers. For desktop virtualisation to deliver a return on investment, the reduction in PC support costs and capital expenditure on desktops must outweigh the extra investment required in the data centre and on the network.

One organisation that has pulled it off – so far – is New College Durham, a secondary and further education college. However, as head of systems George Wraith explained at VMware’s recent user conference, there were some ‘banana skins’ that nearly sent it flying along the way.

In 2008, prompted by growing demand for IT services but limited space and power in its data room, the company virtualised its servers, and with great success. Doing the same for the PC estate seemed like an easy win. With around 1,600 PCs, many of which were dotted around campus, the benefits of centralised management were appealing. The college was also keen to migrate from Windows Vista to Windows 7. “We were one of the few organisations that went through the pain of moving to Vista, and we couldn’t wait to get off it,” says Wraith.

“Once we had successfully implemented server virtualisation, it was practically a no-brainer to move into a VDI [virtual desktop infrastructure] environment.”

The college decided to use VMware’s View desktop virtualisation platform and Wyse P20 ‘zero clients’, which have no software on them and therefore do not require regular updates. It split the implementation up into three phases of around 500 machines each, and began the first phase in the summer of 2010. This phased approach proved invaluable, Wraith says, as it allowed the college’s IT departments to learn some hard lessons quickly, and with minimal impact.

Capacity planning

The first of these occurred during the capacity planning phase. The college was told by the IT consultancy advising it that capacity planning would cost £3,000, so initially it was reluctant. “We thought: we’ve got a good server estate with good back-end storage, and it will all work – why do we need to pay £3,000 for someone to tell us that?”

In the end, the capacity planning exercise was well worth it. “It showed that we had significant IOPS [input/output per second] shortage on our storage infrastructure,” recalls Wraith. That meant investing in the storage infrastructure, which in turn meant going back to the CFO for more capital.

“It’s lucky this happened before the roll-out had started, when the college could still have pulled out if it wanted to,” says Wraith. “I wouldn’t have wanted to be the one going back to the CFO, cap in hand, halfway through the project.”

At first, Wraith decided to use the extra capital to buy a new SSD-based storage area network. Having agreed a budget with an SSD SAN supplier, the college ran a proof-of-concept project and it all worked perfectly. But when Wraith went back to the supplier, it doubled its asking price.

Instead of buying the SAN, therefore, Wraith chose to invest the money in storage network acceleration cards from Fusion I/O. That did the trick, and cost less money than had been allocated to the storage upgrade. “At the final business evaluation, we got to say we’d saved some of the extra capital.”

Durham New College is currently in the third and final phase of its desktop virtualisation implementation. Wraith reports that the number of IT staff required to support the virtual desktop estate is just two, compared with five needed for the conventional desktops, and one of those two is for cover. “It only really needs one,” he says.

The expected savings from capital spending on PCs are even greater. Before the virtual desktop project, the college upgraded its PCs every three to four years. “We were spending a quarter of a million pounds a year on desktop replenishment,” Wraith recalls.

The college’s capital expenditure on the VDI environment was £340,000 in 2010, £250,000 this year and is expected to be £240,000 next year, when the project will earn its return on investment.

Future savings depend on how long the zero clients last. “Depending on which white paper you believe, they can last from ten years up to 25 years,” says Wraith.

If they last for ten years, the college will have saved £1.2 million, Wraith estimates. “If they last for 25 years, I’ll be really impressed.”