sudarshan-uc / vmware-pv-migrate

Overview

The intent of this project is to provide an example workflow of how one can migrate persistent volumes between datastores.

Note: These steps were compiled from tests in my environment. You are responsible for ensuring that you backup data and test any migration to ensure data is migrated properly.

Requirements

• govc is installed and on the path
• GOVC environment variables are exported such that govc can create a virtual disk on the desired datastore
• oc is installed and on the path
• user account with cluster-admin privileges on the OpenShift cluster where the storage is to be migrated

Preparing

• Identify the persistent volume claims to be migrated
• Create a folder in the target datastore to contain the newly created VMDKs
• Ensure the PVCs to be migrated do not have an active pod. Note: For core operators such as monitoring, the cluster-version-operator may need to be scaled down along with any other operators which may reconcile to restart a scaled down pod. This process will require some downtime for services using storage to be migrated.

Migration

Migration follows this workflow:

1. Identify PV associated with the PVC to migrate
2. Identify running workloads using the PVC and scale them down.
3. Create a virtual disk of the same size in the target datastore
4. Create a temporary PV/PVC referencing the new virtual disk
5. Start a job to migrate data from the original to the new virtual disk
6. Set the retention policy on the original PV to Retain to ensure the original disk remains in the event the migration is unsuccessful
7. Delete the temporary PVC/PV and original PVC
8. Create new PV and PVC(of the same name as the original PVC) pointing to the new virtual disk
9. Scale up workloads

Note: It is strongly recommended that backups be taken of any data prior to migration. While care is taken to preserve the original data, taking a backup is good practice ahead of a migration.

The steps in the process have been recorded in a sample script migrate.sh. To use the script:

1. Update TARGET_DATASTORE, TARGET_FOLDER, and PVC to reflect the destination where data is to be stored and the name of the PVC to migrate.
2. Run source migrate.sh
3. Ensure oc project is pointing to the project which contains the PVC to migrate.
4. Ensure any workloads using the PVC to be migrated are scaled down.
5. Run the following steps one at a time checking the output from each step before proceeding to the next:

MIGRATE_PV_GET_RESOURCES
MIGRATE_PV_CREATE_TEMP_PV_PVC
MIGRATE_PV_MIGRATE_DATA
MIGRATE_PV_CLEAN_UP_TEMPORARY_RESOURCES
MIGRATE_PV_SWITCH_TO_MIGRATED_DATA

6. Scale up workloads associated with the PVC.