Finally, a legacy system's health may deteriorate due to external influences. These external influences may include new software standards or new demands for connectivity that emerge over time. If modifications to accommodate these influences include additional layers of software, they can often have a deleterious effect on system health. When a system is terminally ill, its return to a healthy state is not expected. Either the enterprise need has progressed far beyond the capabilities of the software, or the software is in such a case of disrepair that it cannot be economically restored to good health.
Managers are understandably reluctant to part with software in which they have invested heavily.
When time and money and politics are involved, it is hard to let go, even when it is obvious to a dispassionate observer that the time of the legacy system has passed. Assessment, diagnosis, and prognosis is as difficult in legacy system health as it is in human health. Careful analysis is required, but even after careful analysis experts may disagree about the nature and severity of the ailment, the nature of the treatment, and the prospects for recovery. Just as in human health, the technology for treating legacy system ill-health marches on. The next section will present a taxonomy of operational activities.