发布时间:2023-04-19 18:00
在主库与从库上建立专用的复制账号
MariaDB [employees]> create user 'repl'@'172.%' identified by '123456';
注意在生产上的密码必须依照相关规范以达到一定的密码强度, 并且规定在从库上的特定网段上才能访问主库
在主库与从库上授予复制权限
MariaDB [employees]> grant replication slave on *.* to 'repl'@'172.%';
配置主库
注意启用二进制日志需要重启服务, 而server_id是一个动态参数, 可以结合命令行与配置文件以达到免重启的持久化配置. 注意server_id在集群中是唯一的.
[mysqld]
log_bin = /var/log/mysql/mariadb-bin
log_bin_index = /var/log/mysql/mariadb-bin.index
binlog_format = row
server_id = 101
NOTE: 把日志与数据分开是个好习惯, 最好能放到不同的数据分区
配置从库
选项log_slave_update
决定是否把中继日志relay_log存放到本机的binlog中, 如果是配置链路复制, 那么该选项必填. 注意server_id在集群中是唯一的.
[mysqld]
# replication
log_bin = /var/log/mysql/mariadb-bin
log_bin_index = /var/log/mysql/mariadb-bin.index
server_id = 102
# slaves
relay_log = /var/log/mysql/relay-bin
relay_log_index = /var/log/mysql/relay-bin.index
relay_log_info_file = /var/log/mysql/relay-bin.info
log_slave_updates = ON
read_only
初始化从库的数据
此处使用mysqldump在主库上进行备份, 在生产上建议大家用xtrabackup进行无锁的热备(基于innodb引擎).
备份主库上的employees数据库的数据
mysqldump --single-transaction --master-data=1 --triggers --routines --databases employees -u root -p >> backup.sql
将备份文件backup.sql
通过scp或者docker volume卷挂载到从服务器上, 并且导入至从库中
mysql -u root -p < backup.sql
启动复制链路
现有master@172.20.0.2
和slave@172.20.0.3
, 并且已经通过mysqldump将数据同步至从库slave中. 现在在从服务器slave上配置复制链路
MariaDB [(none)]> CHANGE MASTER TO MASTER_HOST='master', MASTER_USER='repl', MASTER_PASSWORD='123456', MASTER_LOG_FILE='mariadb-bin.000029', MASTER_LOG_POS=516;
Query OK, 0 rows affected (0.02 sec)
在从库上启动复制链路
MariaDB [(none)]> start slave;
Query OK, 0 rows affected (0.01 sec)
在从库上检查slave状态
Slave_IO_Running
与Slave_SQL_Running
必须为YES, 如果出现错误须详细阅读Last_IO_Error
或Last_SQL_Error
的提示信息
MariaDB [(none)]> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: master
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mariadb-bin.000029
Read_Master_Log_Pos: 516
Relay_Log_File: relay-bin.000002
Relay_Log_Pos: 539
Relay_Master_Log_File: mariadb-bin.000029
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: 516
Relay_Log_Space: 831
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: 101
Master_SSL_Crl:
Master_SSL_Crlpath:
Using_Gtid: No
Gtid_IO_Pos:
Replicate_Do_Domain_Ids:
Replicate_Ignore_Domain_Ids:
Parallel_Mode: conservative
1 row in set (0.00 sec)
在主库检查dump线程
检测是否已经正确启动binlog dump线程
MariaDB [(none)]> show processlist \G
*************************** 1. row ***************************
Id: 7
User: root
Host: 172.20.0.1:41868
db: employees
Command: Sleep
Time: 56
State:
Info: NULL
Progress: 0.000
*************************** 2. row ***************************
Id: 10
User: repl
Host: 172.20.0.3:45974
db: NULL
Command: Binlog Dump
Time: 246
State: Master has sent all binlog to slave; waiting for binlog to be updated
Info: NULL
Progress: 0.000
可以看到row 2上有Command为Binlog Dump的命令被启动, 证明复制线程已经被成功启动
总结
优点
缺点
在一主多从环境下, 若旧master宕机后在集群中选举出新master, 其他的从库要对这个新的master进行重新同步, 由于每个DB的binlog都是独立存在, 所以很难找出开始同步的日志点