Not every application should be migrated the same way. The six Rs is a widely used framework for deciding what to do with each workload. Choosing the right R for each system is the core of a good migration plan.
1. Rehost (lift and shift)
Move the application to cloud virtual machines with little or no change. It is the fastest route and a good fit when you are under time pressure, for example a data centre exit. The trade-off is that you gain fewer cloud benefits and may pay more to run it.
2. Replatform
Make small optimisations during the move without changing the core design, such as switching a self-managed database to a managed database service. You get lower operational effort for a modest amount of extra work.
3. Repurchase
Replace the application with a SaaS product. This suits commodity systems such as email, CRM or HR where a vendor product does the job better than something you maintain yourself.
4. Refactor (re-architect)
Redesign the application to use cloud-native services such as containers, serverless and managed data services. It costs the most and takes the longest but delivers the best scalability and long-term running cost for systems that matter strategically.
5. Retire
Switch off applications nobody uses. Migration discovery often finds systems that can simply be decommissioned, which cuts cost and reduces your security exposure.
6. Retain
Leave a workload where it is, for now. Reasons include regulatory constraints, a recent hardware investment or very high migration risk. Revisit the decision later.
How to choose
For each workload, weigh up the following before choosing an R.
- Business value: does the system justify investment in re-architecture?
- Technical fit: will it run in the cloud without major change?
- Risk and compliance: what data does it hold and who regulates it?
- Timeline: is there a hard deadline such as a contract or hardware end of life?
- Cost: compare the running cost in the cloud with the current cost, including people.
Where Baywater Consulting fits in
Our cloud migration planning service assesses your estate, assigns the right strategy to each workload and produces a phased roadmap. We then deliver set-up and migration on Azure, AWS or Google Cloud, and can support the environment afterwards.