Mysqlマスターからマスターへの切り替え

    mysql     ，  master   ，    slave  ，
              ，           ，
                                  。

## mysql       ：
     
old slave: 
show processlist；#    Slave has read all relay log;
STOP SLAVE IO_THREAD
show slave status \G;  IO SQL      ，   NO       

stop slave;
reset master;
reset slave all;(    )

grant replication slave on *.* repl@'IP' identified by 'replpwd';
show master status;#       log_file log_pos  
------------------------------------------------------------------------------
##      
old master:
Reset master;(  slave，  master)
Reset slave;

change master to master_host="IP",
master_port=3306,
master_user="repl",
master_password="replpwd",
master_log_file="...",#       log_file
master_log_pos="...";#       log_pos

start slave;
show slave status\G;