The world is constantly changing. There are new technologies and platforms. They promise a more effective solution to the existing problems. This leads to the fact that sooner or later everybody faces the problem of transition on the new platform or information system. But not all agree "to start life with a clean page." Everyone wants to save all the accumulated information and not just save, but make it part of the new system. And this desire is the reason that at the end of the list of objectives of the project of replacement platform or information systems is a small task - data migration. But the small task often hides big problems.