On System Scalability

A significant number of systems fail in initial use, or even during integration, because factors that have a negligible effect when systems are lightly used have a harmful effect as the level of use increases. This scalability problem (i.e., the inability of a system to accommodate an increased workload) is not new. However, the increasing size (more lines of code, greater number of users, widened scope of demands, and the like) of U.S. Department of Defense systems makes the problem more critical today than in the past. This technical note presents an analysis of what is meant by scalability and a description of factors to be considered when assessing the potential for system scalability. The factors to be considered are captured in a scalability audit, a process intended to expose issues that, if overlooked, can lead to scalability problems.