OKD 4 clusters are different from OKD 3 clusters. OKD 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 OKD 3 to 4 see About migrating from OpenShift Container Platform 3 to 4.
Before migrating from OKD 3 to 4, review the differences between OKD 3 and 4 for information about the following areas:
You can migrate stateful application workloads from OKD 3 to 4 at the granularity of a namespace. To learn more about MTC see Understanding MTC.
If you are migrating from OKD 3, see About migrating from OKD 3 to 4 and Installing the legacy Migration Toolkit for Containers Operator on OKD 3.
Review the following tasks to install the MTC:
You upgrade the Migration Toolkit for Containers (MTC) on OKD 4.9 by using OLM. You upgrade MTC on OKD 3 by reinstalling the legacy Migration Toolkit for Containers Operator.
Before you migrate your application workloads with the Migration Toolkit for Containers (MTC), review the premigration checklists.
You can automate your migrations and modify MTC custom resources to improve the performance of large-scale migrations by using the following options:
You can perform the following troubleshooting tasks:
You can roll back a migration by using the MTC web console, by using the CLI, or manually.
You can uninstall the MTC and delete its resources to clean up the cluster.