This was one of the questions tackled by John Phelps, research director at analyst firm Gartner, at last week's Gartner Symposium and IT Expo in San Diego.
"Through to year end 2005, half the enterprises that cannot cost-justify consolidation will go ahead with the project anyway," he warned. "More than 30% of Unix and Windows 2000 consolidation projects will miss their estimated savings by more than 50%."
The reason for this is that consolidation is becoming a buzzword in marketing, and effective utilisation of server space seems to make good economic sense. Phelps said this belief in assured reductions in total cost of ownership will drive people to overlook the real issues.
A major consideration is whether the cost of the larger servers required, licensing and deployment will actually prove to be cheaper than continuing with individual servers.
Consolidation brings its own set of problems, such as whether the applications will work together. Some applications have peak usage times and these must be allowed for.
If two applications sharing a server have peak usage times that coincide, the system has to be powerful enough to cope, but can the extra horsepower be justified for the rest of the time? The impact on bandwidth also has to be considered.
In short, planning is everything, and Phelps recommends that a project team includes IT managers and representatives from the business units affected, moderated by upper management sponsorship, to avoid political stand-offs.
"One of the most critical steps in any server consolidation project is setting proper expectations, especially with upper management," said Phelps.
"We have seen successful consolidation projects be perceived as failures because of improperly set expectations in many areas."
Up-front costs have to be understood because they will be high and may take time to recoup. Even the argument that simplified management will require fewer staff has to be examined carefully because the extra staff are often moved to other duties.
Large Intel boxes such as the Unisys ES7000 will soon be appearing from other suppliers under the title of "Intel mainframes" but Phelps believes that this description is only partially true.
"Partitioning and workload management technology for Unix and Windows systems will not achieve the same level of consolidation capability as the mainframe through until 2006," he insisted.
The two principal consolidation considerations
It is important to understand the difference in cost of multiple smaller systems compared to a larger system that offers partitioning.
That difference must be more than compensated for with consolidation benefits. The benefits will be dependent on things such as dynamic reconfiguration, the degree of resource sharing, inter-partition communication, the granularity of reconfigurable resources, and the ease and automation of shifting resources among partitions.
There are still many differences, some very subtle, among workload management products.
All control the CPU resource to some degree, but the way it is controlled and the number of other resources managed will affect the ability to manage diverse workloads.
The flexibility of defining different workload policies for the different resource consumers and the granularity of the feedback provided by the system are extremely important.
Also, the degree of automation is important because diverse workloads constantly interact differently and could require a high degree of manual intervention.