The project, which began as an experimental study 30 months ago, has enabled the Staffordshire council to cut the number of physical servers it uses from about 50 to six. The servers run 40 virtual machines under VMware ESX.
Steve Clark, network support assistant at the council, said the initial aim was to cut the costs for powering, maintaining and cooling the server farm.
"A cheap trial system evolved into a full-scale solution," he said. "We started with one host server and a handful of small applications. That worked well, but we were concerned about it being a single point of failure, so we added another physical server.
"At that stage we were running GSX [VMware's entry level product] on two physical servers with 14 virtual servers. Then we went for ESX [VMware's top-end product] and added another 12 virtual servers and decommissioned the redundant physical servers."
Clark estimated that the council would save at least £280,000 in running costs over the next three years, and possibly the same again from cuts in hardware costs, maintenance, time and space. "We don't need to buy another server for the next 18 to 24 months," he said.
"Some applications, typically those with lots of simultaneous users, need a dedicated server. But it was a shock to find many of the original servers were so under-utilised that was a real eye-opener."
The council's system consists of six HP dual-processor servers and a 1.2Tbyte EqualLogic storage area network with about 450 PCs. It runs 35 main applications, of which about half have been virtualised so far.
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