We know that cassandra can not support more than node bootstrap at one time, while the
cassandra.consistent.rangemovement is true and
cassandra.consistent.simultaneousmoves.allow is false and if there exist one node be of
bootstrapping/leaving/moving status . If more thant one node doing boostrap, there may exist replica data being not consistent. But actually add new node one by one is time cost , especially when adding a new node will cost very long time.
So we want to add more than one node at one time.