Determining the effort required to complete a migration project is a difficult task.

All estimates are based upon prior experience and your organization might never have done a project of this type. A migration might seem like a small task and perhaps it is, no two projects are exactly alike. When you have to estimate the complexity of the project look for the number of business decisions that need to be made for the project to succeed, rather than focusing on the IT implementation.

The complexity of the project typically scales with these factors

• The number of different data entities to be migrated
• The number of years the old system has been in service

Notedly absent from the list is the number of data rows to be transferred. It is almost as easy to migrate a million customers as it is to migrate a few thousand.

Data entities

The number of data entities is actually a placeholder for the number of business decisions that must be made in the project. The complexity depends both upon the original system and the receiving system.

The scaling is pretty much linearly. Twice the number of data entities means twice the time.

The number of years the old system has been in service

The number of years the old system has been in service is also a placeholder for business decisions. It is very likely that the old system contains technical limitations and historical artifacts. This is due to the fact that business requirements change over time. People in your organization have previously decided how to implement these changing needs. It is likely that they chose to implement the change as efficiently as possible. Often these quick-fix implementations sidestep good development practices in favor of low-cost implementation. As time goes by these changes grow. When you need to migrate data out of the system you will discover that some of these quick fixes now comes back to bite you, making your migration harder and more complicated.

Business decisions are the key

The quick reader will notice that both factors mentioned above are actually substitutes for the same key figure namely the number of business decisions.

The key question then becomes “How many decisions can you make per week?”

This question will vary wildly from company to company since it is primarily a function of company culture.

I have never experienced a migration project where IT-resources was the bottleneck. It is always the business resource that is in highest demand.

In a more plain language, you might say that in enterprise migration projects writing the requirements is the problem, not the implementation of these requirements.

The solution is to establish a good project governance model where business decisions can be made with minimal effort.