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Chapter 1. Migration from OpenShift Container Platform 3 to 4 overview

OpenShift Container Platform 4 clusters are different from OpenShift Container Platform 3 clusters. OpenShift Container Platform 4 clusters contain new technologies and functionality that result in a cluster that is self-managing, flexible, and automated. To learn more about migrating from OpenShift Container Platform 3 to 4 see About migrating from OpenShift Container Platform 3 to 4.

1.1. Differences between OpenShift Container Platform 3 and 4

Before migrating from OpenShift Container Platform 3 to 4, you can check differences between OpenShift Container Platform 3 and 4. Review the following information:

1.2. Planning network considerations

Before migrating from OpenShift Container Platform 3 to 4, review the differences between OpenShift Container Platform 3 and 4 for information about the following areas:

DNS considerations
- Isolating the DNS domain of the target cluster from the clients.
- Setting up the target cluster to accept the source DNS domain.

You can migrate stateful application workloads from OpenShift Container Platform 3 to 4 at the granularity of a namespace. To learn more about MTC see Understanding MTC.

Note

If you are migrating from OpenShift Container Platform 3, see About migrating from OpenShift Container Platform 3 to 4 and Installing the legacy Migration Toolkit for Containers Operator on OpenShift Container Platform 3.

1.3. Installing MTC

Review the following tasks to install the MTC:

1.4. Upgrading MTC

You upgrade the Migration Toolkit for Containers (MTC) on OpenShift Container Platform 4.18 by using OLM. You upgrade MTC on OpenShift Container Platform 3 by reinstalling the legacy Migration Toolkit for Containers Operator.

1.5. Reviewing premigration checklists

Before you migrate your application workloads with the Migration Toolkit for Containers (MTC), review the premigration checklists.

1.6. Migrating applications

You can migrate your applications by using the MTC web console or the command line.

1.7. Advanced migration options

You can automate your migrations and modify MTC custom resources to improve the performance of large-scale migrations by using the following options:

1.8. Troubleshooting migrations

You can perform the following troubleshooting tasks:

1.9. Rolling back a migration

You can roll back a migration by using the MTC web console, by using the CLI, or manually.

1.10. Uninstalling MTC and deleting resources

You can uninstall the MTC and delete its resources to clean up the cluster.