Displaying Slave Status

Before we start troubleshooting threads, I’ll present an excellent source of replication state information: the SHOW SLAVE STATUS query for slaves.

The following examples were taken when running a slave without errors and a slave whose master has stopped to show how errors would look. I’ll discuss the output in chunks.

mysql> SHOW SLAVE STATUS\G
*************************** 1. row ***************************
               Slave_IO_State: Connecting to master

This is the status of the I/O thread. For a running slave, it usually contains Waiting for master to send event:

               Slave_IO_State: Waiting for master to send event
                  Master_Host: 127.0.0.1
                  Master_User: root
                  Master_Port: 4041
                Connect_Retry: 60
              Master_Log_File: mysqld511-bin.000007