# Replatforming COTS and in-house applications FAQ
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This section provides answers to commonly raised questions about replatforming COTS and in-house applications.

## When should I choose to replatform instead of rehosting?
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You should replatform non-database components if the OS vendor has discontinued security updates (for example, RHEL 5 and Windows 2008). For unsupported OSs, you can rehost components to an isolated private subnet and upgrade them before you deploy them to a production environment.

For database components, you should evaluate if replatforming to a commercial database on Amazon RDS is an appropriate choice. You can also use a self-managed database running on Amazon EC2 if the database's vendor allows you to use your current license on the AWS Cloud.

## Can I refactor my COTS application to an open-source database?
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It's possible to refactor a COTS application to an open-source database if your application's vendor supports open-source databases. We don’t recommend using open-source databases for COTS applications without obtaining the vendor's support.

## What AWS tools can I use to quickly rehost my servers to the AWS Cloud?
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You can use [MGN](https://docs.aws.amazon.com//mgn/latest/ug/what-is-application-migration-service.html) as your primary migration service to lift and shift your applications to AWS.

## What AWS tools can I use for replatforming my applications?
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There are several tools available on the AWS Cloud including:
+ [Systems Manager automated upgrades](https://docs.aws.amazon.com//AWSEC2/latest/WindowsGuide/automated-upgrades.html) – Upgrade Windows 2008 and SQL Server 2008 on the AWS Cloud. 
+ [AWS SCT](https://docs.aws.amazon.com//SchemaConversionTool/latest/userguide/CHAP_Welcome.html) – Convert database schema from commercial to open-source databases. 
+ [AWS DMS](https://docs.aws.amazon.com//dms/latest/userguide/Welcome.html) – Replicate data from on-premises databases to the AWS Cloud, either on Amazon RDS databases or databases running on Amazon EC2.