There are several reasons for organizations wanting to migrate their applications to the cloud. These reasons typically include driving cost efficiency, improving productivity, supporting faster go-to-market strategies, achieving better operational efficiency, and others. Additionally, there are also several different strategies employed to move a portfolio of applications to the cloud.
One of the most commonly used approaches is the lift-and-shift, or rehosting, existing applications in the cloud. This approach can lead to some cost savings, especially if the infrastructure is right-sized and expensive commercial licenses of proprietary products replaced with cloud-based services (from the cloud service provider or third-party service providers) or using equivalent open-source products.
This approach is very popular compared to other approaches as it can be quicker to implement, and some benefits may be realized right away. However, design limitations and application inefficiencies in the existing in-premise application also get migrated to the cloud along with the application. Typically, steady-state applications that are service-oriented, loosely coupled, and with minimal inter dependencies with other applications are the best candidates for using this approach.
A rehosting strategy can lead to disappointments when a changeover to a cloud environment does not yield the expected levels of cost savings or a simpler operating environment. This may be because the full benefits of the cloud are fully realized only when cloud-native designs are implemented for various parts of the architecture. However, resizing infrastructure as per application requirements or replatforming the application to use cloud services or open-source products will definitely lead to increased cost advantages but also take longer to implement.
Most times, subscribing to a product's cloud-based offering or shifting to another equivalent or better cloud product can prove to be an advantageous strategy. For example, shifting to cloud-based offerings of SAP or shifting over to Salesforce for CRM functionality is increasingly becoming a favored strategy in many organizations. Finally, for some systems, it is best to re-factor and/or re-architect the application for deriving the maximum benefits of a migration to the cloud. Whatever the reasons and the strategy for migrating systems to the cloud, it needs to be a well-planned exercise that includes infrastructure, application, and data migration, with significant verification and validation effort at each step in the process.
Typically, migration projects start with an analysis of the existing portfolio of applications to figure out the sequence and strategy for each system to be migrated. Additionally, the speed of such projects picks up as a result of increased exposure to the cloud environment based on the initial set of migrations. The overall strategy in many cases is a mass lift-and-shift followed by iterative improvements introduced in the application architecture over a period of time. Sometimes these migrations are timed to avoid expensive lease and license renewals, and/or hardware refreshes. The portfolio analysis exercise often consolidates and/or rationalizes the hardware and software stacks used in an organization, identifies applications that can be retired at specific points along the journey, and other applications that will never be migrated due to regulatory or other concerns.