Replication Source Thread States •  Waiting on cond •  Writing to net •  Finished reading one binlog; switching to next binlog •  Master has sent all binlog to slave; waiting for more updates •  Sending binlog event to slave •  Waiting to finalize termination •  Checking master version •  Connecting to master •  Queueing master event to the relay log •  Reconnecting after a failed binlog dump request •  Reconnecting after a failed master event read 1854 The thread is trying to reconnect to the source. The thread has read an event and is copying it to the relay log so that the SQL thread can process it. The thread is attempting to connect to the source. A state that occurs very briefly, after the connection to the source is established. The following list shows the most common states you see in the  State  column for a replication I/O thread on a replica server. This state also appears in the  Replica_IO_State  column displayed by  SHOW REPLICA | SLAVE STATUS , so you can get a good view of what is happening by using that statement. A very brief state that occurs as the thread is stopping. Binary logs consist of  events , where an event is usually an update plus some other information. The thread has read an event from the binary log and is now sending it to the replica. The thread has read all remaining updates from the binary logs and sent them to the replica. The thread is now idle, waiting for new events to appear in the binary log resulting from new updates occurring on the source. The thread has finished reading a binary log file and is opening the next one to send to the replica. The following list shows the most common states you may see in the  State  column for the  Binlog Dump  thread of the replication source. If you see no  Binlog Dump  threads on a source, this means that replication is not running; that is, that no replicas are currently connected. The server is writing a packet to the network. A generic state in which the thread is waiting for a condition to become true. No specific state information is available. 8.14.4 Replication Source Thread States 8.14.5 Replication I/O Thread States