Tech #101 – What is a Legacy System?

Tech #101 - What is a Legacy System?

A legacy system, in the context of computing, refers to outdated computer systems, programming languages or application software that are used instead of available upgraded versions.

In theory, it would be great to be able to have immediate access to use the most advanced technology. But in reality, most organisations have legacy systems - to some extent. A legacy system may be problematic, due to compatibility issues, obsolete or lack of security support.

Organisations can have compelling reasons for keeping a legacy system, such as:

1 - The system works satisfactorily, and the owner sees no reason to change it.

2 - The costs of redesigning or replacing the system are prohibitive because it is large, monolithic, and/or complex.

3 - Retraining on a new system would be costly in lost time and money, compared to the anticipated appreciable benefits of replacing it (which may be zero).

4 - The system requires near-constant availability, so it cannot be taken out of service, and the cost of designing a new system with a similar availability level is high.

5 - The way that the system works is not well understood. Such a situation can occur when the designers of the system have left the organisation, and the system has either not been fully documented or documentation has been lost.

6 - The system works satisfactorily, and the owner sees no reason to change it.

However there are quite often very good reasons why you should consider either replacing a legacy system or going down a Hybrid route of mixing the old with the new.

Look out for other great posts on this topic on our blog.