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1. 背景
* MySQL Replication默认都是异步（asynchronous），当主库在执行完一些事务后，是不会管备库的进度的。如果备库不幸落后，而更不幸的是主库此时又出现Crash（例如宕机），这时备库中的数据就是不完整的。简而言之，在主库发生故障的时候，我们无法使用备库来继续提供数据一致的服务了。
* Semi sync Replication(半同步复制)是在master上提交完成后，再传送到slave等待ack应答，仅仅在一定情况下事务的已经传递到一个slave上，但是并不确保已经在备库上执行完成，会造成最后一次events的主备不一致。
* lossless replication(无损复制)是在master提前过程中，传送到slave中等待应答。当至少一个slave request bilog后写入到relay-log并flush disk，就返回ack
2. lossless replication传输过程
3. 环境
* master 实例环境
mysql> system cat /etc/redhat-release CentOS release 6.8 (Final) mysql> system ifconfig eth0 | sed -rn '2s#^.*addr:(.*) Bca.*$#\1#gp' 172.18.0.1 mysql> show variables like 'version'; +---------------+------------+ | Variable_name | Value | +---------------+------------+ | version | 5.7.18-log | +---------------+------------+ 1 row in set (0.00 sec)* slave 实例环境
mysql> system cat /etc/redhat-release CentOS release 6.8 (Final) mysql> system ifconfig eth0 | sed -rn '2s#^.*addr:(.*) Bca.*$#\1#gp' 172.18.4.1 mysql> show variables like 'version'; +---------------+------------+ | Variable_name | Value | +---------------+------------+ | version | 5.7.18-log | +---------------+------------+ 1 row in set (0.00 sec)* master 实例my.cnf文件
[mysqld] ########basic settings######## # 主从server-id一定要设置不同 server-id = 110 port = 3306 user = mysql bind_address = 0.0.0.0 character_set_server=utf8mb4 skip_name_resolve = 1 datadir = /data/mysql_data log_error = error.log #######replication settings######## master_info_repository = TABLE relay_log_info_repository = TABLE # MySQL复制是基于binlog日志的 log_bin = bin.log sync_binlog = 1 log_slave_updates # MySQL binlog格式搭建主从时必须设置为row binlog_format = row relay_log = relay.log relay_log_recovery = 1 slave_skip_errors = ddl_exist_errors ######semi sync replication settings######## # 设置插件目录路径 plugin_dir=/usr/local/mysql/lib/plugin # 加载插件 plugin_load = "rpl_semi_sync_master=semisync_master.so;rpl_semi_sync_slave=semisync_slave.so" # 开启master semi sync replication rpl_semi_sync_master_enabled = 1 # 开启slave semi sync replication rpl_semi_sync_slave_enabled = 1 # 等待5秒无ack应答自动切换为异步模式 rpl_semi_sync_master_timeout = 5000 # 开启lossless replication rpl_semi_sync_master_wait_point= AFTER_SYNC # 至少有1个slave接收到日志 rpl_semi_sync_master_wait_for_slave_count = 1* slave 实例my.cnf文件
[mysqld] ########basic settings######## server-id = 210 port = 3306 user = mysql bind_address = 0.0.0.0 character_set_server=utf8mb4 skip_name_resolve = 1 datadir = /data/mysql_data log_error = error.log # slave上开启只读，避免应用误写导致主从数据不一致 read_only = on super_read_only = on #######replication settings######## master_info_repository = TABLE relay_log_info_repository = TABLE log_bin = bin.log sync_binlog = 1 log_slave_updates binlog_format = row relay_log = relay.log relay_log_recovery = 1 binlog_gtid_simple_recovery = 1 slave_skip_errors = ddl_exist_errors ######semi sync replication settings######## plugin_dir=/usr/local/mysql/lib/plugin plugin_load = "rpl_semi_sync_master=semisync_master.so;rpl_semi_sync_slave=semisync_slave.so" loose_rpl_semi_sync_master_enabled = 1 loose_rpl_semi_sync_slave_enabled = 1 loose_rpl_semi_sync_master_timeout = 5000 rpl_semi_sync_master_wait_point = AFTER_SYNC rpl_semi_sync_master_wait_for_slave_count = 14. 搭建无数据基于无损全复制主从 [ master原来无数据 ]
* Master 创建复制所使用的用户 [ 此处ip设置为slave服务IP或者% ]
mysql> grant replication slave on *.* to 'rpl'@'172.18.4.1' identified by '123'; Query OK, 0 rows affected, 1 warning (0.00 sec)* master服务器上查看binlog文件名和日志位置
mysql> show master status; +------------+----------+--------------+------------------+-------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | +------------+----------+--------------+------------------+-------------------+ | bin.000002 | 689 | | | | +------------+----------+--------------+------------------+-------------------+ 1 row in set (0.00 sec)* slave服务器上设置master信息
未开启slave服务时，Slave_IO_Running与Slave_SQL_Running状态成No
master_log_file 设置开始复制文件, master_log_pos 开始文件复制点
mysql> show slave status; # 未开启复制功能时，slave状态是空的 Empty set (0.00 sec) mysql> change master to master_host='172.18.0.1',master_user='rpl',master_password='123',master_log_file='bin.000002',master_log_pos=689; Query OK, 0 rows affected, 2 warnings (0.03 sec) mysql> show slave status\G *************************** 1. row *************************** Slave_IO_State: Master_Host: 172.18.0.1 Master_User: rpl Master_Port: 3306 Connect_Retry: 60 Master_Log_File: bin.000002 Read_Master_Log_Pos: 689 Relay_Log_File: relay.000001 Relay_Log_Pos: 4 Relay_Master_Log_File: bin.000002 Slave_IO_Running: No Slave_SQL_Running: No Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 689 Relay_Log_Space: 154 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: NULL 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: 0 Master_UUID: Master_Info_File: mysql.slave_master_info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec)* 开启slave服务，并查看状态
正常开启slave服务后，Slave_IO_Running与Slave_SQL_Running状态成Yes
mysql> show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 172.18.0.1 Master_User: rpl Master_Port: 3306 Connect_Retry: 60 Master_Log_File: bin.000002 Read_Master_Log_Pos: 689 Relay_Log_File: relay.000002 Relay_Log_Pos: 314 Relay_Master_Log_File: bin.000002 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 689 Relay_Log_Space: 511 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: 110 Master_UUID: d7d5a01b-6ea0-11e7-9773-00163e0432c5 Master_Info_File: mysql.slave_master_info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec)* Master上查看Slave连接信息
mysql> show slave hosts; +-----------+------+------+-----------+--------------------------------------+ | Server_id | Host | Port | Master_id | Slave_UUID | +-----------+------+------+-----------+--------------------------------------+ | 210 | | 3306 | 110 | 499ecfb3-6ea2-11e7-aec1-00163e028c02 | +-----------+------+------+-----------+--------------------------------------+ 1 row in set (0.00 sec)* Master上操作创建数据库与表，并插入数据
mysql> create database mytest character set utf8mb4; Query OK, 1 row affected (0.01 sec) mysql> use mytest; Database changed mysql> create table users( -> id BIGINT NOT NULL AUTO_INCREMENT, -> name VARCHAR(255) NOT NULL, -> sex ENUM('M', 'F') NOT NULL DEFAULT 'M', -> age INT SIGNED NOT NULL DEFAULT '0', -> PRIMARY KEY (id) -> )ENGINE=INNODB DEFAULT CHARSET=utf8mb4; Query OK, 0 rows affected (0.02 sec) mysql> insert into users values(null, 'tom', 'M', 24), (null, 'jak', 'F', 32), (null, 'sea', 'M', 35), (null, 'lisea', 'M', 29); Query OK, 4 rows affected (0.01 sec) Records: 4 Duplicates: 0 Warnings: 0 mysql> select * from users; +----+-------+-----+-----+ | id | name | sex | age | +----+-------+-----+-----+ | 1 | tom | M | 24 | | 2 | jak | F | 32 | | 3 | sea | M | 35 | | 4 | lisea | M | 29 | +----+-------+-----+-----+ 4 rows in set (0.00 sec)* Slave上查看
mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | mytest | | performance_schema | | sys | +--------------------+ 5 rows in set (0.00 sec) mysql> use mytest; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed mysql> show tables; +------------------+ | Tables_in_mytest | +------------------+ | users | +------------------+ 1 row in set (0.00 sec) mysql> select * from users; +----+-------+-----+-----+ | id | name | sex | age | +----+-------+-----+-----+ | 1 | tom | M | 24 | | 2 | jak | F | 32 | | 3 | sea | M | 35 | | 4 | lisea | M | 29 | +----+-------+-----+-----+ 4 rows in set (0.00 sec)5.搭建有数据基于无损全复制主从 [ master原来有数据 ]
* 查看mytest库内容
Database changed mysql> show tables; +------------------+ | Tables_in_mytest | +------------------+ | users | +------------------+ 1 row in set (0.00 sec) mysql> select * from users; +----+-------+-----+-----+ | id | name | sex | age | +----+-------+-----+-----+ | 1 | tom | M | 24 | | 2 | jak | F | 32 | | 3 | sea | M | 35 | | 4 | lisea | M | 29 | +----+-------+-----+-----+ 4 rows in set (0.00 sec)* 使用mysqldump原子导出master库数据，并记录binlog [ 测试只有mytest库 ]
如果有多个库，-B参数后逗号分隔。
[root@master ~]# mysqldump --single-transaction --master-data -B mytest -uroot -p > mytest.sql Enter password:* 将导出的备份文件mytest.sql传输到slave
[root@master ~]# scp ./mytest.sql root@172.18.4.1:/root* slave创建相同的数据库，并将备份导入
mysql> create database mytest character set utf8mb4; Query OK, 1 row affected (0.01 sec) [root@slave ~]# mysql -uroot -p mytest < mytest.sql Enter password:* Master 创建复制所使用的用户 [ 此处ip设置为slave服务IP或者% ]
mysql> grant replication slave on *.* to 'rpl'@'172.18.4.1' identified by '123'; Query OK, 0 rows affected, 1 warning (5.01 sec)* 查看备份文件mytest.sql查看binlog文件名和日志位置
[root@slave ~]# grep 'CHANGE MASTER TO' mytest.sql CHANGE MASTER TO MASTER_LOG_FILE='bin.000002', MASTER_LOG_POS=1575;* slave服务器上设置master信息
未开启slave服务时，Slave_IO_Running与Slave_SQL_Running状态成No
mysql> show slave status; # 未开启复制功能时，slave状态是空的 Empty set (0.00 sec) mysql> change master to master_host='172.18.0.1',master_user='rpl',master_password='123',master_log_file='bin.000002',master_log_pos=1575; Query OK, 0 rows affected, 2 warnings (0.02 sec) mysql> show slave status\G *************************** 1. row *************************** Slave_IO_State: Master_Host: 172.18.0.1 Master_User: rpl Master_Port: 3306 Connect_Retry: 60 Master_Log_File: bin.000002 Read_Master_Log_Pos: 1575 Relay_Log_File: relay.000001 Relay_Log_Pos: 4 Relay_Master_Log_File: bin.000002 Slave_IO_Running: No Slave_SQL_Running: No Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 1575 Relay_Log_Space: 154 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: NULL 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: 0 Master_UUID: Master_Info_File: mysql.slave_master_info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec)* 开启slave服务，并查看状态
mysql> start slave; Query OK, 0 rows affected (0.01 sec) mysql> show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 172.18.0.1 Master_User: rpl Master_Port: 3306 Connect_Retry: 60 Master_Log_File: bin.000002 Read_Master_Log_Pos: 1872 Relay_Log_File: relay.000002 Relay_Log_Pos: 611 Relay_Master_Log_File: bin.000002 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 1872 Relay_Log_Space: 808 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: 110 Master_UUID: d7d5a01b-6ea0-11e7-9773-00163e0432c5 Master_Info_File: mysql.slave_master_info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec)* master上mytest库数据操作
mysql> select * from mytest.users; +----+-------+-----+-----+ | id | name | sex | age | +----+-------+-----+-----+ | 1 | tom | M | 24 | | 2 | jak | F | 32 | | 3 | sea | M | 35 | | 4 | lisea | M | 29 | +----+-------+-----+-----+ 4 rows in set (0.00 sec) mysql> insert into mytest.users select null, 'test', 'M', 42; Query OK, 1 row affected (0.01 sec) Records: 1 Duplicates: 0 Warnings: 0 mysql> update mytest.users set name='seasea' where id = 3; Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from mytest.users; +----+--------+-----+-----+ | id | name | sex | age | +----+--------+-----+-----+ | 1 | tom | M | 24 | | 2 | jak | F | 32 | | 3 | seasea | M | 35 | | 4 | lisea | M | 29 | | 5 | test | M | 42 | +----+--------+-----+-----+ 5 rows in set (0.00 sec)* slave上查看
mysql> select * from mytest.users; +----+--------+-----+-----+ | id | name | sex | age | +----+--------+-----+-----+ | 1 | tom | M | 24 | | 2 | jak | F | 32 | | 3 | seasea | M | 35 | | 4 | lisea | M | 29 | | 5 | test | M | 42 | +----+--------+-----+-----+ 5 rows in set (0.00 sec)6. 总结
以需求驱动技术，技术本身没有优略之分，只有业务之分。
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