When migrating the Bosh Director VM to a new datastore using the steps detailed in the article found here, the OpsMan VM does not get migrated and remains on the old datastore.
To migrate the OpsMan VM to the new datastore use the below steps to vMotion the OpsMan VM.
1. Select the OpsMan virtual machine in vCenter.
2. Navigate to "Action" or right-click on the OpsMan virtual machine and choose "Migrate" from the context menu.
3. In the migration wizard, select the "Change storage only" option and click "Next."
4. Select the target storage and click "Next."
5. Finally, click "Finish" to complete the migration operation.
6. You can check the progress of the migration in vCenter's tasks until OpsMan is fully migrated to the target storage device.