message: [doc]Balance stop
diff: @@ -173,6 +173,18 @@ nebula> SHOW HOSTS
  Now partitions and data are evenly distributed on the machines.
  +## Balance stop
  +
  +`BALANCE DATA STOP` command stops the running balance data plan. If there is no running balance plan, an error is thrown. If there is a running plan, the related plan ID is returned.
  +
  +> Since each balance plan includes several balance tasks, `BALANCE DATA STOP` doesn't stop the started tasks , but rather cancel the subsequent tasks. The started tasks will continue until the executions are completed.
  +
  +Input `BALANCE DATA $id` after `BALANCE DATA STOP` to check the status of the stopped balance plan.
  +
  +After all the tasks being executed are completed, rerun the `BALANCE DATA` command to restart balance.
  +
  +If there are failed tasks in the stopped plan, the plan will continue. Otherwise, if all the tasks are succeed, a new balance plan is created and executed.
  +
  ## Balance leader
  Command `BALANCE DATA` only migrates partitions. But the leader distribution remains unbalanced, which means old hosts are overloaded, while the new ones are not fully used. Redistribute RAFT leader using the command `BALANCE LEADER`.
  