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Application Migration Strategies: Rehost vs Replatform vs Refactor – When to Use Which

When migrating applications to cloud, it is important to consider business goals, application capacities, and costs of migration. There are different strategies for different application migration goals. This blog discusses top three widely used strategies — Rehost, Replatform, and Refactor. Keep reading to know which one is suitable for your business need.

It’s great news that you are planning to migrate your application to the cloud. This will definitely bring cost, productivity, and agility benefits to your business, but what’s next?

It’s great news that you are planning to migrate your application to the cloud. This will definitely bring cost, productivity, and agility benefits to your business, but what’s next? 

The next thing is to identify the strategy or approach you should choose for your application migration. Fortunately, there are multiple approaches that you can use to migrate your application to the cloud. 

Here are the strategies you can use for application migration. 

  1. Lift-and-Shift (Rehost) 
  1. Lift, Tinker and Shift (Replatform) 
  1. Refactor 
  1. Complete Rebuild 
  1. Drop and shop 
  1. Containers 
  1. Retire 
  1. Retain 

We are going to discuss the first three strategies in this post. 

You may be thinking, “What’s new in this? I can find plenty of articles online for these application migration options.” 

But wait, I will be addressing scenarios in which a particular approach is useful or advisable. 

Okay, convinced? Let’s understand these cloud application migration strategies one by one. 

Lift-and-Shift or Rehost Strategy

As the name suggests, lift and shift strategy involves lifting a part of the application or a complete application from an on-premises or existing cloud environment to a new cloud environment. It is also referred to as a rehost strategy. 

Here, shifting is done with very little or no modification. While implementing a lift and shift approach, you may be required to change the host configuration if the application is shifting to a new cloud-based hardware. 

Lift and shift is a beginner’s approach to start with application migration or optimization. This approach delivers a quick and easy cloud migration solution as it can be migrated with minimal application disruption.

Large enterprises looking for quick migration without disturbing the existing application workflow generally choose the rehost approach. Once they migrate their application using the rehost approach, it is easy for them to re-architect and optimize the application as they are already done with the difficult part — Application migration to the cloud.

You may choose manual or automated migration. If you are moving your application to the AWS cloud, then you can use automation tools such as AWS VM Import/Export, Racemi, etc.

Curious to know how migrating your application to AWS can help you obtain higher ROI? Talk to AWS experts.

When to use Rehost?

  • Organizations that are more concerned about cost and time to migrate can choose this approach.
  • Organizations are looking to reduce on-premises infrastructure costs immediately.
  • Organizations incur too much cost in maintaining physical infrastructures. For example, if setting up a data operation center costs twice as much as the cloud, it is advisable to move the application to the cloud with minor or no modification.
  • For organizations choosing to move to the cloud and having some applications that just need to keep running without disruption or modification, rehost is a good
  • In the case of commercial and off-the-shelf applications, it is impossible to make code changes on those applications. In this case, it is a better idea to adopt the rehost.
  • Some applications can be easily optimized once migrated to the cloud. For those applications, it is a good strategy to first move them to the cloud by adopting the rehost approach as it is and then optimize.
  • Organizations that are already on cloud and faced with a cloud disaster (e.g. corrupted database) should perform rehost technique to get their applications up and running quickly in a very short time.

Lift, Tinker and Shift or Replatform Strategy

Unlike the lift and shift approach, in Lift, Tinker and Shift approach, a portion of the application or the entire application is optimized or a little before moving to the cloud. Experts suggest that small cloud optimization can bring significant benefits without changing the core application architecture. Minor changes can also help in significant application improvement.

Let’s understand this. Suppose an organization is managing database instances manually in the existing on-premises set up, which requires a significant amount of time. The time required for database management can be reduced by migrating the database instances to the Amazon Relational Database Service if you are moving to AWS.

Replatform approach allows developers to reuse the resources they are accustomed to working with such as legacy programming languages, development frameworks, and existing caches in the application.

When to use Replatform?

  • Organizations that are sure that minor changes won’t affect the application functioning.
  • Organizations willing to automate certain tasks, as mentioned before moving databases to the Amazon Relational Database Service.
  • Organizations are looking to leverage more cloud benefits other than just moving the application to the cloud. 
  • If for moving an application to cloud the source environment is not supporting the cloud, then a slight modification is required.
  • If the on-premises infrastructure is complex and hinders scalability and performance, replatform is a good
  • Organizations are willing to automate tasks which are essentials to operations but are not the business priorities.

Rearchitect or Refactor Strategy

Refactor entails making major changes in the application configuration as well as application code for migration. It is a bit more complex than the above-mentioned two approaches since while making application code changes, it must be ensured that the changes do not impact the external behavior of the application.

For example, if your existing application is resource intensive, it may cause larger cloud billing because it involves big data processing or image rendering. In that case, redesigning the application for better resource utilization is required before moving to the cloud.

You can choose between partial or complete Refactor, depending upon your needs. In partial refactor, a small part of the application is modified, which results in faster migration compared to complete Refactor. A complete refactor involves complete modification of the application, which delivers higher performance and lowers costs.

When to use Refactor?

  • When there is a strong business need for adding features and performance to the application and that is not possible within the existing
  • When an organization is looking to scale their existing application.
  • When restructuring of the code is required to take full advantage of cloud capability.
  • When an organization is looking to boost agility or improve business continuity, factor strategy is a better
  • When an organization is willing to move to a service-oriented architecture (SOA), it can use this approach.

By analyzing your complete IT system, you can identify your infrastructure and your application workload. This assessment will help you determine which strategy to use and which part(s) should be moved to the cloud. Infrastructure that delivers a higher business value should be moved to the cloud for better efficiencies.

If you need help with the application and cloud migration or migration assessment, talk to our cloud expert to avail free consultation.

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