Reducing costs while increasing performance is a conundrum most IT managers face today. Business is demanding more from its technology than ever before while cutting the resources IT needs to deliver the productivity increase.

One way in which IT departments are trying to solve this problem is by sharing server resources between multiple applications. Most servers in large corporations are dedicated to one function only and are not used to their full capacity. This especially applies to Windows servers; these machines are generally only used to between 5% and 10% of their total capacity.

"This has led to higher computing costs and more complexity, with many barely used servers scattered around a company consuming resources desperately needed elsewhere," says Bernard Donnelly, consultancy services manager, Unisys Africa. "Uncontrolled server growth is not sustainable in today's economic climate. IT managers need to focus on reducing waste and squeezing every drop of value out of their infrastructure.



"Sharing resources correctly can make better use of each server without degrading performance and the most common method for sharing resources is virtualisation."

Virtualisation has been around for some time on mainframes and high-end Unix systems, but is now also available for the Windows platform. It breaks the traditional link between an application and its dedicated server by pooling resources and allocating a portion of those resources to each application, depending on need. One server can now run multiple applications.



Enter virtual machines

One method of virtualisation is to share server resources through virtual machine technology, such as VMWare. This technology allows multiple operating systems (not necessarily the same operating system nor the same version) to run on a single server with each system believing it has access to a dedicated server. It is possible, for example, to take 100 servers at 5% to 10% utilisation and move those applications onto 10 physical servers running at 70% to 80% utilisation. Server resources are shared between the virtual servers and each application is protected from interference from others. Unfortunately, this solution does not necessarily deliver all the cost savings one would desire, and actually requires more operating system instances (100 for the virtual servers plus 10 for the underlying physical servers).

Virtual machines are well suited to specific applications - such as supporting legacy applications in transition - in certain environments. However, there are a number of drawbacks:

* Application size: there is an upper limit to the amount of resource that can be allocated to a single application.

* Scale: Windows applications are typically run on a four-way or eight-way server, limiting the scope for resource allocation and hence the scope for this technology as a whole to smaller companies or applications that require limited resources.

* Cost reduction: hardware costs are reduced with virtual machines, but organisations still need to buy and maintain the same number of operating systems. The licensing and operations costs are therefore not reduced. In fact, it is likely that the operations cost will increase due to the addition of a virtualisation layer.

"Reducing hardware costs is great, but it is only the tip of the iceberg. Platform costs only represent about 20% of the total operational spend; we need to cut into the other 80% of the costs to make significant savings," adds Donnelly. "For real cost reductions we need to reduce all the other 'stuff' that goes into the IT infrastructure, such as platform, operating systems, applications, middleware, support and facilities. This is where co-hosting comes into the picture, offering a superior solution that takes all these factors into account."



The co-hosting option

Co-hosting raises the utilisation level of servers to 70% or 80% of maximum capacity by balancing the demands for resources from multiple applications. Importantly, co-hosting technology acknowledges there will be times when certain applications will have extra processing requirements and provides for these peaks and troughs without requiring administrators to reconfigure systems or assign more or less memory, processing power or hard disk space.

By running multiple applications together in a co-hosted environment companies can eliminate much of the 'stuff' described above: they can reduce the number of operating system instances and support applications to the optimum level; reduce the number of connections, facilities as well as staffing levels; manage the systems more closely; and provide consolidated disaster recovery and backup services

"The co-hosting model allows companies to create a flexible resource structure, bringing in the pay for use or resource on demand attributes of a utility model," Donnelly concludes.

"Co-hosting addresses one of the biggest issues facing corporate IT departments today: cost reduction. It allows organisations to consolidate their server farms, substantially reducing the number of servers, operating systems and support requirements, and hence the overall cost of IT. The result will be an optimum cost profile, optimum utilisation levels and a flexible architecture able to handle any changes business may throw at it."

For more information contact Bernard Donnelly, Unisys Africa, 011 233 4000, bernard.donnelly@za.unisys.com