We already talked about different 6R application migration strategies and the differences between them. Today we will extend the original topic by comparing the pros&cons of each strategy.
The application migration strategy is a process of migrating the whole application environment to the cloud. It is usually driven by business decisions for cost optimization, agility, flexibility, scalability, and other cloud technology benefits.
An application migration strategy is based on application discovery. Application discovery is a step in cloud migration in which we examine your IT ecosystem and find all the apps that need to be migrated. Based on the priorities, application importance, and complexity, we create a roadmap and determine the strategy for each application.
Sometimes, we discover that certain applications are no longer used by anyone. This can happen when a certain app is replaced by another app with similar or better functionality. Sometimes, during mergers and acquisitions, certain applications are replaced because of the company's policies.
We eliminate the cost of application infrastructure and license costs if there are any. There are no migration costs.
Retire strategy has no downsides; we simply turn off something that no one uses.
Retain is a decision to keep the application as it is at the moment. Old legacy applications are usually the best candidate for retention - they typically run on older OS's, and there is no justification for cloud migration.
There are no migration costs and no work involved; the application is left the way it is.
There is no area for technical improvement or cost optimization.
Re-host strategy is also referred as lift and shift. This is the first strategy that requires some work. Lift and shift is the simplest strategy; the application is simply taken, as is, from an on-premise environment to the cloud.
This approach is a good choice for companies wanting to migrate quickly.
Speed and risk minimization are the most important advantages of lift and shift migrations. Application and its configuration is taken from an on-premise environment to the cloud; this process is very straightforward and fast, so there is no risk of something going wrong during the migration.
Specialized cloud services give you operational advantages (Amazon Aurora, Amazon Redshift); with lift & shift, you cannot use these services. If the application has some performance or other issues, there is a chance that these problems will remain.
Re-host strategy is also referred as lift and reshape. In this approach, you replace ceratin on-premise technologies and services with similar cloud services. An excellent example of a re-platform is the transition from an on-premise MySQL database to Amazon Aurora.
With re-platform, you are utilizing specialized cloud services. This way, you gain a lot of cloud migration benefits without refactoring or significant code changes. The process of migration is usually automated and fast, so there are no risks.
This strategy requires a bit more planning and coordination. Your team also needs to learn about the way new specialized cloud services function.
Re-architect is a strategy where you need to redesign your application to be more cloud-native. This one is the most advanced cloud strategy and takes some time; it also delivers a significant number of benefits.
Re-architecture usually means taking a monolithic application and turning it into a microservice design.
This migration strategy delivers the most cloud migration benefits. Through the migration process, you are modernizing your application. Usually, new monitoring and logging features are added to have more insight into the health of your system. You gain a log of cloud migration benefits such as increased efficiency, agility, scalability, and cost control.
This strategy can be pretty complex. It requires time, careful planning, understanding of cloud services, and coordination between developers and operations teams. The risk is relatively high, although it is mitigated with careful planning.
This migration strategy is a strategy where we replace existing software with the one in the cloud. An example can be the replacement of your on-premise HR software with the SaaS option.
The advantage of re-purchase is the speed of migration and the level of effort. You are simply replacing old software with the modern variant.
If there are any dependencies, they can be hard to overcome. You need to invest in knowledge and people to use and administer the new solution.
In this article, we talked about the pros and cons of each of the 6R's. Re-architect is the strategy that delivers the maximum number of benefits, but it requires a lot of work. Retire and retain are the simples because they do not require any work. A re-purchase strategy can help you modernize your app and get new features fast. Re-host is the simples actual migration strategy where we take the system and simply move it into the cloud as-is. Re-platform is an interesting strategy that helps you utilize specialized cloud services and get many benefits without too much work.
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