Rehost
Often referred to as a lift and shift migration model. This option doesn't require code changes, and allows you to migrate your existing apps to Azure quickly. Each app is migrated as is, to reap the benefits of the cloud, without the risk and cost associated with code changes. This is arguable the simplest, but could be the most costliest approach to moving to Azure.
The lift and shift approach focuses more of moving applications to an Infrastructure-as-a-Service model. This mainly involves moving an existing application or workload from on-prem deployment to a cloud-provider’s infrastructure. As such, there are often no significant changes to make in the application architecture, data flow, or authentication mechanisms. You should choose this approach when:
you need to move apps quickly to the cloud.
you want to move an app without modifying it.
your apps are designed so that they can take advantage of Azure IaaS scalability after migration.
apps are important to your business, but you don't need immediate changes to app capabilities.
There are tools like Azure site recovery and Database Migration that assist you in this approach. Most of the time, you'll end up with a hybrid infrastructure with a connectivity configured to Azure via Site-Site VPN or Express Route.
The pros of using the re-host strategy for your cloud adoption is:
Easy and simple. No application architectural or code changes needed.
You'll find special VMs in Azure to migrate the compute resources to meet hardware requirements.
Identity services like Azure active directory can be easily moved to Azure. This can be easily facilitated by provisioning additional services like Azure domain services and AD connect to support hybrid scenarios.
Security and compliance management is relatively simple as you can translate the current requirements to control the compute, network and storage resources in Azure.
You can also make use of your current licenses in cloud by making use of the hybrid license plan.
The cons of this approach is:
Could be costliest approach as this might use the cloud resources less efficiently. For e.g most of the time, you'll end up using only 50-60 percent of your available CPU.
Difficult to scale and extend your applications as these features are more compatible and cost effective in PaaS solutions.
If you have chosen the lift and shift approach, once migrated, you should look for opportunities to optimize or slowly refactor your applications to make use of the platform services.
References:
#cloudadoption #cloudmigration #azuremigration #azureadoption #applicationrehosting #liftandshift #liftshift
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