Incorrect value in Relay_Log_Space

show slave status\G

*************************** 1. row ***************************

               Slave_IO_State: Waiting for master to send event

                  Master_Host: dbs01-03

                  Master_User: repl

                  Master_Port: 3306

                Connect_Retry: 60

              Master_Log_File: dbs01-03-bin.002200

          Read_Master_Log_Pos: 646662540

               Relay_Log_File: relay-bin.005515

                Relay_Log_Pos: 646632193

        Relay_Master_Log_File: dbs01-03-bin.002200

             Slave_IO_Running: Yes

            Slave_SQL_Running: Yes

              Replicate_Do_DB: 

          Replicate_Ignore_DB: 

           Replicate_Do_Table:<some tables>

       Replicate_Ignore_Table: 

      Replicate_Wild_Do_Table: sys.date_time,mysql.%

  Replicate_Wild_Ignore_Table: tmp.%

                   Last_Errno: 0

                   Last_Error: 

                 Skip_Counter: 0

          Exec_Master_Log_Pos: 646631902

              Relay_Log_Space: 1722503481

              Until_Condition: None

               Until_Log_File: 

                Until_Log_Pos: 0

           Master_SSL_Allowed: No

           Master_SSL_CA_File: 

           Master_SSL_CA_Path: 

              Master_SSL_Cert: 

            Master_SSL_Cipher: 

               Master_SSL_Key: 

        Seconds_Behind_Master: 0

Master_SSL_Verify_Server_Cert: No

                Last_IO_Errno: 0

                Last_IO_Error: 

               Last_SQL_Errno: 0

               Last_SQL_Error: 

  Replicate_Ignore_Server_Ids: 

             Master_Server_Id: 144

               Master_SSL_Crl: 

           Master_SSL_Crlpath: 

                   Using_Gtid: No

                  Gtid_IO_Pos: 

      Replicate_Do_Domain_Ids: 

  Replicate_Ignore_Domain_Ids: 

                Parallel_Mode: conservative

$ ls -l /base/binlog/relay-bin.*

-rw-rw---- 1 mysql mysql       886 Aug 18 12:18 /base/binlog/relay-bin.005513

-rw-rw---- 1 mysql mysql       338 Aug 18 12:18 /base/binlog/relay-bin.005514

-rw-rw---- 1 mysql mysql 646511803 Aug 18 12:40 /base/binlog/relay-bin.005515

-rw-rw---- 1 mysql mysql        90 Aug 18 12:18 /base/binlog/relay-bin.index

$ cat /base/binlog/relay-bin.index 

/base/binlog/relay-bin.005513

/base/binlog/relay-bin.005514

/base/binlog/relay-bin.005515