Migration prerequisites#

You must meet certain prerequisites to successfully migrate an MSR system using the Mirantis Migration Tool (MMT):

Placement of the source MSR registry into read-only mode. To do this, execute the following API request:
```
curl -u <username>:$TOKEN -X POST "https://<msr-url>/api/v0/meta/settings" -H "accept: application/json" -H "content-type: application/json" -d "{ \"readOnlyRegistry\": true }"
```
A 202 Accepted response indicates success.
Important
- To avoid data inconsistencies, the source registry must remain in read-only mode throughout the migration to the target MSR system.
  
  Revert the value of readOnlyRegistry to false after the migration is complete.
- Be aware that MSR 3.0.x source systems cannot be placed into read-only mode. If you are migrating from a 3.0.x source system, be careful not to write any files during the migration process.
An active MSR 3.x.x installation, version 3.0.3 or later, to serve as the migration target.
Configuration of the namespace for the MSR target installation, which you set by running the following command:
```
kubectl config set-context --current --namespace=<NAMESPACE-for-MSR-3.x.x-migration-target>
```
You must pull the MMT image to both the source and target systems, using the following command:
```
docker pull mirantis/mmt
```
2.9.x source systems only. Administrator credentials for the MKE cluster on which the source MSR 2.9 system is running.
Kubernetes target systems only. A kubectl config file, which is typically located in $HOME/.kube.
Kubernetes target systems only. Credentials within the kubectl config file that supply cluster admin access to the Kubernetes cluster that is running MSR 3.x.x.