Redesigning a product so that it is more maintainable can have many benefits. A key benefit of designing for maintainability is saving the company money in the long run by reducing failures caused by maintenance issues. Designing for maintainability can also help to improve employee morale while increasing productivity. Maintainability is a measure of how easy a product is to maintain. Maintenance may be viewed as existing within at least three overlapping phases: corrective, adaptive and perfective
Corrective maintenance comprises those actions required to bring a system back into its original or working state after some failure occurs such as replacing parts or fixing bugs
Adaptive maintenance involves changes that occur due to environmental changes such as changing requirements or better ways of using the system
Perfective maintenance focuses on making improvements in the system itself by applying knowledge gained over time through corrective and adaptive maintenance activities.
Thus maintainability can be seen as both an objective and/or subjective attribute depending upon whether the maintainer has the required knowledge and skills. For example, consider an automobile mechanic who has the knowledge and skill to correct or adapt a car's behaviour so that it drives well. The same mechanic may have difficulty perfecting the car because of his lack of knowledge about how to do this. So for example changing the timing belt on a 1992 Honda Accord is easy, but adding power windows is much more difficult.
Redesigning a product can also improve usability or ease of use, thus allowing end-users to work around failures instead of maintaining the product. Usability problems increase maintenance costs by requiring additional training, support calls, spare parts inventories and help desk resources. The time required for corrective maintenance should be reduced by making improvements in maintainability/robustness during the design.