The Need for Scalable Architecture

Most organizations today spread their applications across servers based on functional boundaries. Both large and small companies use email servers, file servers, web servers and so on. Over time, the trend has been to dedicate a specific server for each function. This allows for a scalable, highly flexible architecture. As the organization grows, greater demands are placed on the infrastructure. Not just from an increase in the number of users, but also in terms of the geographic footprint. Branch offices will require their own servers for certain applications. Fault tolerance also plays a part, driving larger installations towards multiple, duplicated servers in preference over a single monolithic system.

As servers don’t generally require user interaction, the trend has been to use vendor supplied appliances for certain types of applications. An appliance allows for a relatively small footprint and also provides more of a plug and play infrastructure over the traditional server application experience. As load increases, new appliances can be brought on-stream and the load distributed evenly. The system administrator can maintain a surplus of similar appliances and install these in the event of failure or increased load. Dividing the application base into component parts and spreading these components across multiple appliances is a tried and tested method of delivering a scalable architecture.

However, industry research by VMware shows that the system usage per appliance can be as low as 15% of the available processing power. Effectively, the server budget is over six hundred percent higher than necessary. Maintaining a pool of idle servers on standby in case of increased load or for failure recovery, can adversely affect the efficiency even further. Amalgamating applications on each server can go a long way toward resolving the usage issues but at a cost. Running different applications on the same server loses the scalability of the appliance solution and can create security issues.

In addition, maintaining a homogenous environment of appliances is extremely difficult if not impossible. Complicating this is the need to upgrade different applications at different times. A new appliance can have a different platform configuration which will make it difficult to migrate users from an older appliance to a new one.