In 2011, Gartner outlined 5 Rs – five strategies – for migrating applications to the cloud. These were Rehost, Replatform, Repurchase, Refactor & Retire.
Stephan Orban built on these on the AWS blog in 2016, adding another R into the mix: Retain.
When we talk with customers about the essentials of building a cloud migration strategy, we assert the importance of having a deep understanding of your existing estate (AKA where you are now) alongside clear objectives (AKA defining where you want to go).
The 6 Rs of cloud migration provide a framework for your organization to reconcile these two elements. Most successful cloud transformations use a combination of some or all of these approaches.
For those who don’t know, the 6Rs are:
Rehost (AKA Lift-and-shift) is a popular approach for large-scale migrations where avoiding large capital expenditure on IT infrastructure is attributed as a key driver. As the name suggests, it involves moving your existing estate – as is – onto the cloud.
It is a quick and cost-effective migration solution that is practical if you desire minimal impact on existing workflows. This approach will marginally save on costs, however, it does little to accelerate you towards the benefits of cloud adoption.
Having said that, it is easier to optimize and modernize applications once they are in the cloud – so there is something to be said about lift-and-shift being a good first step in the cloud.
Replatform is a similar approach to rehost but it involves making more optimizations to certain applications in the cloud. These applications will usually be tied to some key/valuable business objective.
You should consider replatforming an application or service, when the on-premise hardware or software reaches end-of-life. This is not only an opportunity to avoid CapEx investment but also to easily deliver scalability. For example, using database services. Replatforming generally offers more opportunities to realize savings than rehosting does
An example of repurchasing would be moving to a/switching SaaS provider. We noticed a lot of organizations repurchasing when the COVID-19 pandemic hit and they needed to rapidly scale mass remote working with collaboration and video conferencing solutions.
Refactoring involves re-architecting your applications using cloud native features.
Rather than just optimizing, you are reimagining applications by moving from monolithic virtual machines to a serverless architecture formed from PaaS services from your CSP.
While this approach delivers further improvements in cost-effectiveness, reliability and scalability, it can also be the most expensive and disruptive.
However, this is where true value can be seen in the cloud and where significant transformation occurs. If your objectives require refactoring, then the juice is worth the squeeze.
When you assess your existing application portfolio, you are more than likely to find apps that are no longer serving a purpose.