Azure SQL is designed to meet you where you are. You don’t have to move everything the same way. Instead, you can apply the “four Rs” to each workload and choose the right Azure SQL service.
The four Rs of migration and modernisation
- Rehost (lift and shift)
Move your existing SQL Server workloads to SQL Server on Azure Virtual Machines with minimal changes.
Best when: you need to move quickly, keep OS-level access, and avoid code changes.
Benefits: fast migration, full SQL Server compatibility, ability to maximise existing licenses.
- Refactor (repackage)
Make small changes so your apps can use Platform-as-a-Service (PaaS) options like Azure SQL Managed Instance or Azure SQL Database.
Best when: you want to reduce operational overhead but keep the core app logic intact.
Benefits: lower management effort, faster and shorter updates, reduced data centre footprint.
- Rearchitect
Modify and extend your apps for the cloud, for example by breaking monolithic apps into microservices and using Azure SQL as a modern data layer.
Best when: you need better scalability, agility and cost efficiency for strategic applications.
Benefits: improved performance, easier scaling, better use of cloud-native services and automation.
- Rebuild
Completely reconstruct the application to fully leverage Azure services and modern development practices.
Best when: the existing app is too constrained or costly to maintain and is blocking innovation.
Benefits: faster innovation cycles, ability to mix technology stacks, and reduced long-term operational costs.
Choosing the right Azure SQL service
- SQL Server on Azure Virtual Machines – ideal for lift-and-shift scenarios and workloads that require OS-level access.
- Azure SQL Managed Instance – a fully managed PaaS option with broad SQL Server engine compatibility, suited for modernising existing SQL Server applications at scale.
- Azure SQL Database – a cloud-native relational database with serverless compute and auto-scaling storage, ideal for modern applications and new solutions.
- Azure SQL Edge – for extending SQL capabilities to IoT and edge scenarios.
Because the entire Azure SQL family is built on the same SQL Server database engine, your existing SQL skills and investments carry forward, which reduces risk and speeds up adoption.
Most organisations use an iterative, wave-based approach: they plan, discover and assess, then migrate and modernise groups of workloads in stages. The Microsoft Cloud Adoption Framework for Azure provides guidance, tools and templates to help you plan, govern and manage this journey with confidence.