As we mentioned in the previous section, there could be various reasons for migrating to the cloud, and those reasons play an essential role in your cloud migration journey. They will help you determine a migration strategy and prioritize applications. In addition to primary business drivers for cloud migration, you could have more reasons related to the data center, business, application, team, and workload for cloud migration.
Often, migration projects adopt multiple strategies and utilize different tools accordingly. The migration strategy will influence the time it takes to migrate and how the applications are grouped for the migration process. The following diagram shows some of the commonly used strategies for migrating existing applications to the cloud:
As shown in the preceding diagram, an organization can take a mix of migration strategies; for example, if an application-hosted operating system is at its end of life, then you need to upgrade the OS. You can take this opportunity to migrate to the cloud for better flexibility. In this case, most likely, you will choose the Replatform method to recompile your code into a new version of the OS and validate all its features. After you've finished testing, you can migrate the application to the OS hosted in the infrastructure provided by the cloud.
You can do a Lift and Shift of the server or application from the source environment to the cloud. Migrating a resource only needs minimal changes for it to work in the cloud. To take a more cloud-native approach, you can refactor your application to fully utilize the cloud-native feature, for example, converting monolithic into microservice. If your application is a legacy application and cannot be moved, or it is not cloud compatible, you may want to retire it and replace it with a cloud-native SaaS product or third-party solution.
Your business objectives will drive your decision to migrate applications and their priority and strategy for migration. For example, when cost efficiency is the main driver, the migration strategy typically involves mass migration with a heavy focus on the Lift and Shift approach. However, if the main goal is to enable agility and innovation, the cloud-native approach (such as rearchitecting and refactoring) plays a key role in the cloud migration strategy. We'll learn more about each strategy in the following subsections.