What is data migration?

A company moves from an old accounting package and a handful of spreadsheets to a new system. On the first day the customers, suppliers, items and open invoices must already be in it. Moving them over is the data migration.

It sounds like copying, but it is more. Old data contains duplicates, outdated customers, items not sold for years, and fields that are named differently in the new system or do not exist there. You have to decide what to take along, what to clean up, and how old fields fit into new ones.

Without care you carry the clutter across. Duplicate relations lead to double payments, a wrong item number to a wrong delivery, and wrong open items to an opening balance that does not agree. Errors made now are hard to find later.

Watch three things. Decide beforehand which data you need; taking more is not always better. After loading, check that the totals agree with the old system. And plan the migration so that you can test before the real switch, since that decides when go-live can happen.

A migration is also an opportunity. Remove what you no longer use, give items a clear code and record who is responsible for what. That way a new ERP starts from a clean base.

Appoint someone who knows the data and can judge whether the result is right. That is usually someone from your own company, not the person loading the files. Have them check a sample beforehand: customers, items and open items.