【MySQL案例】error.log的Warning：If a crash happens thisconfiguration does not guarantee that the relay lo

1.1.1. If a crash happens thisconfiguration does not guarantee that the relay log info will be consistent

【環境描述】

msyql5.6.14

【報錯資訊】

mysql的slave啟動時，error.log中出現Warning警告：

[Warning] Slave SQL: If a crash happensthis configuration does not guarantee that the relay log info will beconsistent, Error_code: 0

這條Warning資訊對Mysql和MySQL複製功能沒有任何影響。

【報錯原因】

         MySQL5.6版本開始支援把master.info和relay-log.info的內容寫入到mysql庫的表中，

                   master.info--> mysql.slave_master_info

                   relay-log.info--> mysql. slave_relay_log_info

         同時在MySQL5.6版本中，增加了 Slave crash-safe replication功能，為了保證mysql的replication能夠crash-safe，slave_master_info和slave_relay_log_info表必須使用事務型的儲存引擎（InnoDB），不要嘗試去手動修改這兩張表的內容。同時，Slave還要開啟relay_log_recovery功能。

【解決方案】

         設定master_info_repository和relay_log_info_repository的值為TABLE，同時開啟relay_log_recovery功能。

         修改/etc/my.cnf設定檔，添加以下3項：

                   master-info-repository=table     # 可以使用set global 動態修改

                   relay-log-info-repository=table   # 可以使用setglobal 動態修改

                   relay-log-recovery=1           # 唯讀參數，必須修改my.cnf重啟mysql

         然後重啟mysql執行個體。

 

【參考資料】

l  master.info和relay-log.info日誌

         在複製的Slave節點上會建立兩個日誌，分別是master.infor和relay-log.info，位於datadir目錄中。在MySQL5.6和後續的版本中，可以通過設定master-info-file和relay-log-info-file參數來指定寫入到mysql的表中或者寫入檔案。

         這兩個檔案中包含一些類似showslave status輸出的資訊，當slave啟動的時候會讀取master.info和relay-log.info檔案來確定從master讀取binary log和讀取relay log的資訊。

         Slave的I/O線程負責更新維護master.info檔案，

master.info	mysql.slave_master_info	SHOW SLAVE STATUS Column	Description
1	Number_of_lines	[None]	Number of lines in the file
2	Master_log_name	Master_Log_File	The name of the master binary log currently being read from the master
3	Master_log_pos	Read_Master_Log_Pos	The current position within the master binary log that have been read from the master
4	Host	Master_Host	The host name of the master
5	User	Master_User	The user name used to connect to the master
6	User_password	Password (not shown by SHOW SLAVE STATUS)	The password used to connect to the master
7	Port	Master_Port	The network port used to connect to the master
8	Connect_retry	Connect_Retry	The period (in seconds) that the slave will wait before trying to reconnect to the master
9	Enabled_ssl	Master_SSL_Allowed	Indicates whether the server supports SSL connections
10	Ssl_ca	Master_SSL_CA_File	The file used for the Certificate Authority (CA) certificate
11	Ssl_capath	Master_SSL_CA_Path	The path to the Certificate Authority (CA) certificates
12	Ssl_cert	Master_SSL_Cert	The name of the SSL certificate file
13	Ssl_cipher	Master_SSL_Cipher	The list of possible ciphers used in the handshake for the SSL connection
14	Ssl_key	Master_SSL_Key	The name of the SSL key file
15	Ssl_verify_server_cert	Master_SSL_Verify_Server_Cert	Whether to verify the server certificate
16	Heartbeat	[None]	Interval between replication heartbeats, in seconds
17	Bind	Master_Bind	Which of the slave's network interfaces should be used for connecting to the master
18	Ignored_server_ids	Replicate_Ignore_Server_Ids	The number of server IDs to be ignored, followed by the actual server IDs
19	Uuid	Master_UUID	The master's unique ID
20	Retry_count	Master_Retry_Count	Maximum number of reconnection attempts permitted Added in MySQL 5.6.1)

 

         Slave的SQL線程負責維護relay-log.info檔案，在MySQL5.6中relay-log.info包含檔案中的記錄數和複寫延遲的秒數。

relaylog.info	slave_relay_log_info	SHOW SLAVE STATUS	Description
1	Number_of_lines	[None]	Number of lines in the file or rows in the table
2	Relay_log_name	Relay_Log_File	The name of the current relay log file
3	Relay_log_pos	Relay_Log_Pos	The current position within the relay log file; events up to this position have been executed on the slave database
4	Master_log_name	Relay_Master_Log_File	The name of the master binary log file from which the events in the relay log file were read
5	Master_log_pos	Exec_Master_Log_Pos	The equivalent position within the master's binary log file of events that have already been executed
6	Sql_delay	SQL_Delay	The number of seconds that the slave must lag the master

 

設定master_info_repository和relay_log_info_repository參數：

SQL> stop slave;

SQL> set global master_info_repository=table;

SQL> set global relay_log_info_repository=table;

SQL> show variables like '%repository';

+--------------------------------------+---------+

| Variable_name           | Value |

+--------------------------------------+---------+

| master_info_repository    | TABLE |

| relay_log_info_repository  | TABLE |

+--------------------------------------+----------+

 

查看向Master讀取日誌的情況：

SQL> select * from slave_master_info;

查看Slave的Relay日誌應用情況：

SQL> select * from slave_relay_log_info;

 

注意：
         master.info和relay-log.info內的資料會有一定的延遲，取決於mysql把slave資訊刷到硬碟的時間，如果要獲得slave的即時資訊，可以查詢slave_master_info和slave_relay_log_info表，或者執行show slave status查看。

 

l  master-info-repository

    master-info-repository={ FILE | TABLE }，預設值是FILE，這個參數用於設定Slave節點上把master的資訊寫入到物理檔案中還是寫入到mysql. slave_master_info表中。

    如果設定為FILE，也是mysql的預設設定，Slave會在datadir/master.info檔案中記錄master的資訊，從MySQL5.6版本開始，建議使用TABLE模式。

 

l  relay-log-info-reposity

         relay-log-info-reposity=file|table，預設值是FILE，這個參數用於設定slave節點上把relay-log.info的資訊寫入到datadir/relay-log.info檔案或者mysql. slave_relay_log_info表。

    如果設定為FILE，也是mysql的預設設定，Slave會在datadir/master.info檔案中記錄master的資訊，從MySQL5.6版本開始，建議使用TABLE模式。

 

l  relay-log-recovery

         relay-log-recover=0|1，預設值是0不開啟，該參數用於設定是否開啟relay log的自動回復功能。當開啟relay_log_recovery功能，slave資料庫在啟動的時候，會忽略未被執行的relay log，它會重新串連master擷取relay log來進行恢複。

         當slave發生宕機的時候，建議開啟該功能，可以有效避免slave執行了relay log裡面的訛誤記錄。

         如果開啟relay_log_recovery功能，必須同時把relay_log_info_reposity設定為TABLE模式。