I have done the following testing:

1. I applied one log item to three nodes, and persisted.
2. delete persist data from one node (not leader) and start raft (other nodes keep alive).
3. raft log will not be applied for this node, there is some log on this node:
   raft: AE no log at prev_idx 1
   send: {"myid": 1, "message_type": "append_entries_response", "term": 1, "success": 0, "current_idx": 0, "first_idx": 2}

Then it will be loopback forever.