一、服务器环境MySQL5.7MGR集群切换目标：故障切换，启用备选主之后。还原MGR，切换回原主服务器信息[root@0321-mysqlmgr3~]#cat/etc/hosts127.0.0.1localhostlocalhost.localdomainlocalhost4localhost4.localdomain4::1localhostlocalhost.localdomainloc