迁移不过就是永不退回的故障转移，扩展是永远不将主节点置于离线的故障转移。

Migration is simply a failover that never fails back, and scaling up is a failover in which the primary node never goes offline.

youdao

不然的话，就算是最老练的公司们也不得不退回到原先制定的分配系统。

Even the most sophisticated companies have to fall back on established distribution systems.

youdao

因此，他们不得不退回到了漫长的道路。

So they had to fall a long way.

youdao