> For the complete documentation index, see [llms.txt](https://ysfang82.gitbook.io/development-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ysfang82.gitbook.io/development-notes/aws-notes/service/migration/cloud-migration-the-6r.md).

# Cloud Migration: The 6R

6R

* Rehosting: "Lift and shift"
  * Simple migrations by re-hosting on AWS (applications, databases, data)
  * No cloud optimizations being done, application is migrated as is
  * Ex. migrating AWS VM Import / Export, AWS [Server Migration Service](https://docs.aws.amazon.com/zh_tw/server-migration-service/latest/userguide/server-migration.html)
* Replatforming
  * No changing the core architecture, but leverage some cloud optimizations (containerize)
  * Ex. migrate a database to RDS, or an application to Elastic Beanstalk
* Repurchase: "drop and shop"
  * Moving to a different product while moving to the cloud
  * Often you move to a SaaS platform
  * Expensive in the short term, but quick to deploy
  * Ex. CRM to Salesforce.com, HR to Workday, CMS to Drupal
* Refactoring / Re-architecting
  * Refactor applications with Cloud Native principals
  * Ex. move an application to Serverless, use S3.
* Retire
  * Turn off things you don't need
* Retain
  * Do nothing, just keep it as it is


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