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Migration with Modernisation on AWS: A Better Alternative to Rehosting

In today’s digital era, organisations continuously seek strategies to maintain their competitive edge. A prevalent method involves updating their IT infrastructure and applications. However, the prospect of migration and modernization can be daunting for many organisations, prompting them to opt for a more straightforward solution – rehosting. This approach allows them to experience basic cloud benefits while simultaneously exiting a data centre and laying the groundwork for digital transformation.

Rehosting involves moving existing applications and servers to a cloud platform, such as AWS, without making any changes to the underlying technology. This involves moving your applications and other workloads running on your on-premise infrastructure to a cloud infrastructure. For example, migrating 1000 servers from on-premise to AWS without major architectural changes to the applications powered by these 1000 servers. While this may seem like an easier and quicker solution, it often results in missed opportunities for improvement and potentially increased costs in the long run.

On the other hand, migration with modernisation on AWS allows organisations to take advantage of the full range of cloud services and benefits, while also modernising their applications and infrastructure.  In such cases, the application components are analysed individually, mapped to equivalent cloud-native service, and rebuilt to run natively on cloud’s managed services. For example, migration of mainframe applications to AWS or adopting microservices (Amazon Lambda) to decouple services in an application. This approach not only improves reliability, scalability, security, agility and performance but also reduces costs. It also positions the organisation for future growth and innovation.

Drivers for migration with modernisation on AWS include:

  • Improved performance and scalability: By taking advantage of AWS services such as auto-scaling, organisations can improve application performance and ensure that they can handle increasing amounts of traffic as their business grows. And scale back down when the demand reduces; allowing them to give a great customer experience at the right price point.
  • Increased efficiency and reduced costs: Modernising applications on AWS can also help organisations optimise their IT infrastructure, reducing the number of servers required and reducing the costs associated with running their IT systems.
  • Improved security and compliance: With built-in security features and compliance certifications, AWS helps organisations meet their security and compliance requirements, reducing the risk of data breaches and regulatory penalties.
  • Future-proofing: By modernising their applications and infrastructure, organisations can future-proof their IT systems, ensuring that they are ready for new technologies and innovations in the future.
  • Reducing Technical debt: Modernisation provides an organisation with the ability to reduce its infrastructure debt by removing the burden of maintaining and upgrading the underlying infrastructure of data centres, while empowering it to focus on developing new and innovative solutions. 
  • Sustainability: Sustainability is a hot topic these days – most organisations have Sustainability and ESG goals. Research shows that AWS can lower customers’ workload carbon footprints by nearly 80% compared to surveyed enterprise datacenters, and up to 96% once AWS is powered with 100% renewable energy, expected in 2025. It is also uniquely positioned to address your ESG (Environmental, Social & Governance) priorities.

Re:host:Lift & Shift

Lift & Shift migration is a method of moving existing applications and infrastructure from an on-premises environment or a traditional data centre to a cloud environment, such as Amazon Web Services (AWS), without making any changes to the underlying technology. The objective of this type of migration is to quickly and easily move existing systems to the cloud without the need for extensive testing, reconfiguration, or application modification. This is generally a good practice to do when there is a compelling need or a data centre exit is right round the corner. This approach is well suited for organisations with simple IT environments or those looking to quickly move their applications to the cloud as a stepping stone to more advanced migration strategies.

However, while Lift & Shift migrations can be a fast and easy way to move applications to the cloud, they do not take full advantage of the benefits of cloud computing. Applications that are not optimised for the cloud may suffer from performance issues, increased costs, and reduced security. Therefore, organisations may need to consider more advanced migration strategies, such as re-architecting or re-platforming, in order to fully optimise their applications for the cloud.

Re:architect (Modernisation)

Modernisation  is the process of updating, improving, or transforming existing systems, applications, or processes to meet current or future needs and expectations. This can involve updating the technology, architecture, or design of an existing system to take advantage of new advancements and to address limitations or challenges.

Modernisation  can occur in many areas, including IT systems, software development, business processes, and organisational structures. Sometimes it starts with code change of a legacy application – doing a re-architect of the said application. And more often, it could mean a complete rewrite of the application to suit the new goals. Overall, modernisation is an important process for organisations to stay ahead of the curve and remain competitive in today’s rapidly changing digital landscape.

Modernisation as a part of Cloud Migration

Move to Cloud Native Architecture: Event Driven Architecture with Lambda, Serverless + containers, reactor with microservices

Move to Managed Cloud Services: AWS auto-managed infrastructure incl. Containerisation using ECS, EKS, cloud messaging, Code Star, CI/CD

Move to Managed Databases: Purpose-built AWS databases and streaming (Aurora, DynamoDB, Redshift, Kinesis)

Move to Open Source: It could mean an absolute code change like for example net to .net core, Windows to Linux, SQL Server to Aurora PostgreSQL

Which path to choose?

When choosing between Lift & Shift migration and Modernisation , several parameters should be considered:

  • Business goals and objectives: The desired outcome of the migration should drive the selection between Lift & Shift and Modernisation . If the objective is to quickly move applications to the cloud, Lift & Shift may be the best option. But if the goal is to improve performance, scalability, security, and efficiency, modernisation is likely the better choice. Modernisation enables large organisations to leave behind the legacy application architecture and adopt cloud-native technologies that help them innovate and move fast, competing with their major competitors – tech startups in their domain.
  • Complexity of applications and infrastructure: If the systems are simple and straightforward, Lift & Shift may be the best option, but if the systems are complex, modernisation may be necessary to take full advantage of the cloud. Adopting lift-and-shift migration is pretty straightforward and once done in a short period and with almost zero downtime, the business leaders start buying into this idea that cloud, after all, is not very complex and cooperates for future cloud adoptions.
  • Cloud-readiness of applications: If the applications are not optimised for the cloud, modernisation may be necessary to ensure that they perform well and take advantage of the full range of cloud services.
  • Budget and resources: Lift & Shift migrations are often faster and less expensive than modernisation projects, but they may not provide the same benefits in the long run. Modernisation often requires a detailed level of planning that may run into several weeks for each application. Because modernisation is not just a function of cloud infrastructure adoption, but more to do with changes to the application technology and adoption of managed cloud services, organisations looking to keep the initial migration costs under will opt for a lift-and-shift migration model.
  • Long-term Cost Benefits: While the lift-and-shift method of migration might look cost-effective in the short term, thanks to less planning time and automated migration tools, you end up spending more in the long-term when compared to the modernisation method. 

Cost considerations of a rearchitect vs a rehost:

When most of the time, talking to CIOs and IT Transformation directors, re:architect can be often frowned upon because of the costs and budgeting constraints. The costs of a migration project can differ significantly depending on whether the migration is a re-host or a re-architect. This is most of the time a factor that often influences the decision. 

It’s important to note that the cost of a migration project can also vary depending on factors such as the complexity of the existing systems, the cloud-readiness of the applications, the budget and resources available, and the security and compliance requirements of the organisation. Overall, the cost of a migration project will depend on a variety of factors and will vary from one organisation to another.

In my experience, a re-architect will cover the ROI in a 3-4 year period. In this example, I have taken liberty of a project where I did costing comparison for a complex application. In this case, the customer recovered their costs in 2.5 years and had a modern, cloud native application. 

Migration Cost (one time)£20,000£100,000
Consumption (annually)£22,000£2,600
Managed Services (annually)£24,000£6,000
in 2.5 years£135,000£121,500

If you would like to hear more about this scenario and our approach to modernising the monolith applications on AWS, please listen to our Spotcast below or watch the Youtube video here

In my experience where I have been able to create a case for modernisation vs a Lift & Shift migration, it has been mainly to pick one application and modernise it. The savings generated from this migration is then fueled into the modernisation for the 2nd and so on and so forth. There are even funding programs from AWS like Migration Acceleration Program that help cover some of the costs and act as a vehicle towards a customers’ successful cloud transformation. Hear me speak with AWS on how to map your journey to AWS here

Can innovation decide the migration pathway?

Most organisations have innovation as a big driver in today’s time. A company can achieve innovation and stay ahead of its competitors by opting for a rearchitect migration, rather than a rehost migration, when migrating its systems and applications to the cloud. This often is a good way to create that case for change – when you not only innovate the ways of working but also have big tech like AWS innovate on your behalf by releasing newer services. 

Rehost migrations (Lift & Shift) can quickly move existing systems to the cloud, but they often result in limited benefits, as the applications are not optimised for the cloud. Rearchitect migrations, on the other hand, involve rethinking and transforming existing systems and applications to take full advantage of the benefits of cloud computing. This approach can help organisations achieve innovation by allowing them to:

  1. Adopt new technologies: Rearchitect migrations enable organisations to adopt new technologies and cloud-native services that can improve performance, scalability, security, and efficiency.
  2. Improve user experiences: Rearchitect migrations can help organisations to take advantage of new features and capabilities offered by cloud platforms.
  3. Increase competitiveness: Rearchitect migrations can help organisations to respond more quickly and effectively to changing market conditions and customer needs.
  4. Lower costs: By optimising systems and applications for the cloud, organisations can take advantage of the scalability and efficiency benefits offered by cloud computing.


When talking to organisations about their cloud journey, I often suggest doing:

  1. Rehost (Lift & Shift) and then modernise: You could choose this model if data centre exit is of high priority and/or if there are cloud adoption budget constraints.
  2. Modernisation with Migration (Re-platform): If you wish to achieve a balance between migration and an acceptable degree of modernisation, then this re-platform will suit your needs.

Cloud adoption models vary depending on the specific scenarios, but embracing a modernisation approach can offer significant benefits in terms of both business transformation and long-term cost savings. One effective strategy is to adopt a “modernisation after migration” model, which enables you to swiftly transition away from your on-premise infrastructure and then consistently modernise your applications on the cloud, providing the advantages of both worlds. However, unless you are 100% certain that modernisation will happen after the migration, otherwise most organisations never go back to it. The famous saying of “why break a working system” is often said. I believe that you must touch a working system to update, upgrade and make it future-ready. And that can only be achieved via modernisation. 

As a long-standing AWS Partner, Devoteam has a strong expertise in AWS solutions deployment and management. Our AWS certified consultants are ready to help your company move its activities to the Cloud using AWS.

Contact us for more information on how we can help you with AWS.

Prabhat Handoo
Cloud Strategy & Advisory Lead