What happens during adop phase=cutover ?

The phase adop phase=cutover , has many tasks.  

• Validations: First on primary node and then on all slave nodes in parallel
• Shutdown of services: Parallel on all slave nodes followed by primary node
• DB Cutover: Only on primary node, rest all slave nodes wait
• FS Cutover: Parallel on all nodes
• Startup of services: First on primary node and then on all slave nodes in parallel

Note that all these subtasks are completed sequentially one after the other i.e. each subtask should be complete on all nodes before proceeding to the subsequent subtask.