https://cloud.google.com/blog/products/cloud-migration/real-world-cloud-migration-strategies
When helping customers plan large-scale migrations of applications to the cloud, we here on the Professional Services team sometimes observe them pouring countless hours into the top-down evaluation of their application estate and categorizing them into discrete migration strategies like “rehost”, “replatform”, “refactor” and so on. It’s a well established industry practice in which the only open point for debate, it seems, is whether there are 5, 6, 7 or 8 distinct “R’s”.
In practice, the popular “R” migration strategies aren’t really strategies at all—they’re placeholders for all the things you don’t yet know about your applications. We find that an IT organization's policies and capabilities do more to determine the migration path than anything else and ultimately override any architect’s prior top-down planning.
