Planning

Keep in mind these few things when assessing a migration from on-prem to any cloud.

1. Assessment

Build a business case. Cover questions that management may have both on the business and technical side.

• Cost
• Architecture
• Security

After migrating to the cloud, is there a difference?

2. Proof of concept

Deploy a light version of the app in the cloud. Make sure all the critical features work. If they don't, is there a permanent fix that can be applied?

3. Data migration

Understand which file storage, databases, data lakes and archives work best for the migrated app.

4. App Migration

A few methods to deploy to the cloud:

• Forklift. Lift and shift apps as they are. Suitable for organisations that have limited resources to explore the cloud's full capabilities. Get-things-done type of management. Future scaling may face challenges.
• Hybrid. The app is part on-prem, part-cloud. Organisations may choose to maintain the app on-prem but have the storage in the cloud to save on storage and archiving cost. Unexpected behaviour is a risk.
• Using images. Developers use images to spin up instances in the cloud to replicate the one on-prem.

AWS Cloud Migration Guide

5. Leverage the cloud

The more sophisticated way of actually saying use more AWS services.

CloudWatch to monitor, AZ to build in resilience, ELB to load balance, Elastic Beanstalk to manage deployment.

6. Optimization

Improve optimization, efficiency, latency, monitoring, and re-engineering it.

Migration strategies

The 6 Rs of cloud migration:

Rehost. Moving apps to cloud without making modifications to it. Good for business cases that save cost simply by moving to the cloud (even without optimisation). The management is usually in the mindset of move first, optimise later. It's also known as lift and shift.

Replatform. Moving apps to the cloud with different platforms like servers, licenses, and network infrastructure. Motivation may be to save on license cost by using cloud services that only charge for usage. Using open source software is also an option.

Refactor. Aka rearchitect. For example, redesigning the app from monolithic to microservice design. Expensive and time consuming, but optimizes apps for the long run. Slowest of the 6 strategies.

Repurchase. Using cloud SaaS (Software as a Service). Salesforce, Workday, ServiceNow, WorkChat, and Gmail are some examples of cloud based SaaS products that are readily available to be purchased. This strategy is more suitable for companies that prefer to buy first, build for competitive advantage in the Build, Buy, Partner model.

Retire. Decommissioning apps that do not serve business purposes. Some companies may not be aware that they have redundant apps that are still running. Some studies claim that it saves up to 10% of IT cost. Fastest of the 6 strategies.

Retain. Revisiting the organisation's applications and making decisions to refactor, optimize or remove them.

Other considerations

• Which business app should be migrated to the cloud first?
• How to reduce reliance on existing vendors?
• If a hybrid model is deployed, what are the dependencies between applications?
• Does the on-prem architecture replicate exactly in the cloud?
• Can licenses be reused or must it be pay-as-you-go cloud license?