Software Maintenance Implications on Cost and Schedule

Software Maintenance Implications on Cost and Schedule. The dictionary defines maintenance as, "The work of keeping something in proper order." However, this definition does not necessarily fit for software. Software maintenance is different from hardware maintenance because software doesn't physically wear out, but often gets less useful with age. Software is typically delivered with undiscovered flaws. Therefore, software maintenance is: "The process of modifying existing operational software while leaving its primary functions intact." Maintenance typically exceeds fifty percent of the systems' life cycle cost. Additionally, software is highly dependent on defined maintenance rigor and operational life expectancy. Software maintenance generally includes sustaining engineering and new function development; corrective changes (fixing bugs); adapting to new requirements (OS upgrade, new processor); perfecting or improving existing functions (improve speed, performance); enhancing application with (minor) new functions (new feature.) Since software maintenance costs can be somewhat set by definition, the implications on cost and schedule must be evaluated. Development decisions, processes, and tools can impact maintenance costs. But, generally even a perfectly delivered system quickly needs upgrades. While software maintenance can be treated as a level of effort activity, there are consequences on quality, functionality, reliability, cost and schedule that can be mitigated through the use of parametric estimation techniques.