Companies with Public-Cloud-First or Public-Cloud-Only strategies are quite common today. The cloud not only looks attractive but is also in many cases an actual alternative to traditional IT purchasing and delivery models and provides tangible benefits – adaptable costs, fast scalability, and relief for infrastructure management. You know all that. But when a company has been in the market for a few years (or even decades), it’s very likely that somewhere in a corner of its (in-house) data center an old and traditional (legacy) system is still happily churning out data. And usually for business-critical purposes too. It’s one of those “better don’t touch” situations. I know what I’m talking about. There are a considerable number of such systems in our data centers – mostly in caged areas.
And what now? As early as 2011, Gartner put forward the 5-R strategy for the migration of applications to the cloud. And a little later, Stephen Orban of AWS refined and expanded this approach (on 6 R). He states that in addition to Rehost, Replatform, Repurchase, and Refactor/Rearchitect, the Retire and Retain options also exist. That is: switch off or preserve/retain in the existing state.