。本文将详细介绍如何使用 MySQL 自带工具 mysqld_multi 实现主从复制,并配置多个 MySQL 实例来简化管理和提高系统的可靠性。
chou403
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写在前面
正常情况是准备需要主从个数的服务器,每个服务器都安装好 mysql,主库数据内容同步到从库中。
本次记录是在一台机器通过 mysqld_multi 操作一主两从数据库服务。若多台服务,则将配置文件拆分配置即可。
本次安装使用了 HomeBrew,若用其他方式,或者路径不一致,/opt/homebrew/opt/mysql 更改成自己的安装路径即可。
配置文件
安装 mysql
brew install mysql进入 mysql 安装之后的默认启动目录
cd /opt/homebrew/opt/mysql创建数据目录 data,data 内创建三个文件夹,分别命名为 3306,3307和3308。
mkdir data
cd data
mkdir {3306,3307,3308}3306,3307和3308 文件夹就是分别放置我们每个实例(mysql 服务器)中的所有数据库,数据表和一些日志文件的地方,每个文件夹可以看到一个 mysql 服务器。
在 mysql 包中新建一个文件,将文件命名为 my.cnf,从此以后,这个文件就是我们需要一直使用的配置文件。
touch my.cnf打开 my.cnf 配置文件,将下列代码复制进入文件中:
[mysqld]
# mysql 安装目录
basedir=/opt/homebrew/opt/mysql
[mysqld_multi]
mysqld=/opt/homebrew/opt/mysql/bin/mysqld_safe
mysqladmin=/opt/homebrew/opt/mysql/bin/mysqladmin
log=/opt/homebrew/opt/mysql/data/mysql_multi.log
[mysqld3306]
mysqld=mysqld
mysqladmin=mysqladmin
# 数据库目录
datadir=/opt/homebrew/opt/mysql/data/3306/data
# 端口
port=3306
# socket 登录 mysqld_multi 启动自动生成 退出 自动删除
socket=/opt/homebrew/opt/mysql/mysql_3306.sock
server_id=1
[mysqld3307]
mysqld=mysqld
mysqladmin=mysqladmin
datadir=/opt/homebrew/opt/mysql/data/3307/data
port=3307
socket=/opt/homebrew/opt/mysql/mysql_3307.sock
server_id=2
[mysqld3308]
mysqld=mysqld
mysqladmin=mysqladmin
datadir=/opt/homebrew/opt/mysql/data/3308/data
port=3308
socket=/opt/homebrew/opt/mysql/mysql_3308.sock
server_id=3
安装实例
安装实例 3306
❯ mysqld --defaults-file=/opt/homebrew/etc/my.cnf --initialize --basedir=/opt/homebrew/opt/mysql/ --datadir=/opt/homebrew/opt/mysql/data/3306/data
2024-01-25T04:45:17.883145Z 0 [System] [MY-015017] [Server] MySQL Server Initialization - start.
2024-01-25T04:45:17.889196Z 0 [System] [MY-013169] [Server] /opt/homebrew/Cellar/mysql/8.2.0_1/bin/mysqld (mysqld 8.2.0) initializing of server in progress as process 60393
2024-01-25T04:45:17.895958Z 0 [Warning] [MY-010159] [Server] Setting lower_case_table_names=2 because file system for /opt/homebrew/opt/mysql/data/3306/data is case insensitive
2024-01-25T04:45:17.910343Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2024-01-25T04:45:18.038467Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
2024-01-25T04:45:18.632405Z 6 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: j.10weTJs)iu
2024-01-25T04:45:18.940457Z 0 [System] [MY-013172] [Server] Received SHUTDOWN from user <via user signal>. Shutting down mysqld (Version: 8.2.0).
2024-01-25T04:45:19.447294Z 0 [System] [MY-015018] [Server] MySQL Server Initialization - end.记住 root 账户初始密码:j.10weTJs)iu
安装实例 3307
❯ mysqld --defaults-file=/opt/homebrew/etc/my.cnf --initialize --basedir=/opt/homebrew/opt/mysql/ --datadir=/opt/homebrew/opt/mysql/data/3307/data
2024-01-25T04:46:02.653813Z 0 [System] [MY-015017] [Server] MySQL Server Initialization - start.
2024-01-25T04:46:02.661065Z 0 [System] [MY-013169] [Server] /opt/homebrew/Cellar/mysql/8.2.0_1/bin/mysqld (mysqld 8.2.0) initializing of server in progress as process 62369
2024-01-25T04:46:02.667029Z 0 [Warning] [MY-010159] [Server] Setting lower_case_table_names=2 because file system for /opt/homebrew/opt/mysql/data/3307/data is case insensitive
2024-01-25T04:46:02.679468Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2024-01-25T04:46:02.771801Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
2024-01-25T04:46:03.385917Z 6 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: a#=MYe)L:8aj
2024-01-25T04:46:03.685023Z 0 [System] [MY-013172] [Server] Received SHUTDOWN from user <via user signal>. Shutting down mysqld (Version: 8.2.0).
2024-01-25T04:46:04.225769Z 0 [System] [MY-015018] [Server] MySQL Server Initialization - end.记住 root 账户初始密码:a#=MYe)L:8aj
安装实例 3308
❯ mysqld --defaults-file=/opt/homebrew/etc/my.cnf --initialize --basedir=/opt/homebrew/opt/mysql/ --datadir=/opt/homebrew/opt/mysql/data/3308/data
2024-01-25T04:46:12.066014Z 0 [System] [MY-015017] [Server] MySQL Server Initialization - start.
2024-01-25T04:46:12.067626Z 0 [System] [MY-013169] [Server] /opt/homebrew/Cellar/mysql/8.2.0_1/bin/mysqld (mysqld 8.2.0) initializing of server in progress as process 62774
2024-01-25T04:46:12.069105Z 0 [Warning] [MY-010159] [Server] Setting lower_case_table_names=2 because file system for /opt/homebrew/opt/mysql/data/3308/data is case insensitive
2024-01-25T04:46:12.071151Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2024-01-25T04:46:12.171156Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
2024-01-25T04:46:12.598694Z 6 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: HJgqw!Bi6Efb
2024-01-25T04:46:12.866118Z 0 [System] [MY-013172] [Server] Received SHUTDOWN from user <via user signal>. Shutting down mysqld (Version: 8.2.0).
2024-01-25T04:46:13.501326Z 0 [System] [MY-015018] [Server] MySQL Server Initialization - end.记住 root 账户初始密码:HJgqw!Bi6Efb
查看多实例
使用mysqld_multi命令查看这些MySQL服务是否开启。
❯ mysqld_multi --defaults-extra-file=/opt/homebrew/opt/mysql/my.cnf report
Wide character in print at /opt/homebrew/bin/mysqld_multi line 684.
Reporting MySQL servers
MySQL server from group: mysqld3306 is not running
MySQL server from group: mysqld3307 is not running
MySQL server from group: mysqld3308 is not running开启多实例
使用mysqld_multi命令开启实例。
❯ mysqld_multi --defaults-extra-file=/opt/homebrew/opt/mysql/my.cnf start 3306,3307,3308再次查看多实例。
❯ mysqld_multi --defaults-extra-file=/opt/homebrew/opt/mysql/my.cnf report
Wide character in print at /opt/homebrew/bin/mysqld_multi line 684.
Reporting MySQL servers
MySQL server from group: mysqld3306 is running
MySQL server from group: mysqld3307 is running
MySQL server from group: mysqld3308 is running查看 mysql 任务线程。
❯ ps aux | grep mysqldsocket方式登录
使用 socket 的方式登录,必须使用 -S 参数,并且在后面加上.sock 文件的位置,需要注意的是,之后每一次登录,都需要使用这种 -S 方式进行登录。
mysql -u root -p -S /opt/homebrew/opt/mysql/mysql_3306.sock系统会提示输入密码,将上面记录的初始密码输入,进入 mysql 服务器。
更改 root 的密码
为了方便,我们将 3306 端口的服务器密码设置为 3306。同样方式更改其他两个。
# 8.0 以下版本 密码模式 mysql_native_password
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '3306';
# 8.0 以上版本 密码模式 caching_sha2_password
ALTER USER 'root'@'localhost' IDENTIFIED WITH caching_sha2_password BY '3306';关闭 mysql 服务器
mysqladmin -S /opt/homebrew/opt/mysql/mysql_3306.sock -uroot -p shutdown。日志文件
MySQL启动日志在哪?
启动动日志记录了MySQL启动时的状态,如果你启动失败可以查看该日志,可以使用最普通的文本编辑器打开,根据ERROR信息进行必要的调整。由于我们的配置文件my.cnf指定了生成路径,该日志在MySQL服务启动后自动生成在你的mysql包内,全称为mysqld_multi.log。
二进制文件在哪?
二进制文件主要记录MySQL数据库的变化,包含了所有更新了数据或者潜在更新了数据(例如没有匹配任何一行的UPDATE)的语句;还包含了每个更新数据库的语句的执行时间信息,使用二进制日志的目的是最大可能的恢复数据库,因为二进制日志包含备份后进行的所有更新,而且二进制文件是主从复制的重要桥梁和关键所在。
我们的二进制文件就在我们最初创建的3306文件夹内,具体路径是mysql/data/3306/data,使用 mysqlbinlog查看二进制文件。
每次重启服务器,都会新生成一个二进制日志,后缀以.000001开始递增。
其它日志文件在哪?
在配置文件中加上一行代码,就可以开启错误日志,当 mysql 需要记录错误发生时,就会保存在我们设置的路径上的日志中。
log_error = /opt/homebrew/opt/mysql/data/3306/data/my_error.log如果我们需要开启通用查询日志,可以在 mysql 中使用命令开启。
mysql> set @@global.general_log = 1;
Query OK, 0 rows affected (0.01 sec)执行成功之后,就会在 mysql/data/3306/data目录下新增一个.log 的日志文件。
如果我们需要开启慢羊羊日志
mysql> set @@global.slow_query_log = 1;
Query OK, 0 rows affected (0.01 sec)执行成功之后,就会在 mysql/data/3306/data目录下新增一个-slow.log 的日志文件。
多实例解耦
在上文中,我们把若干个实例的配置信息放在同一个配置文件my.cnf中,如果若干个实例都是通过同一个配置文件启动,那么耦合性就太高了,试想一下,当我们同时开启了若干个实例,例如同时开启了3306,3307和3308MySQL服务,而在中途突然需要改变一下3306服务的配置,那么修改配置文件之后进行MySQL服务的重启,又因为服务重启是通过配置文件启动的,而其它实例的配置内容又在同一份文件中,那么有可能在对3306修改时造成对其它实例的影响。
基于上述问题,为了降低MySQL各个服务的耦合度,我们可以通过创建多个配置文件来生成多个实例,通俗一点说,一个单独的MySQL服务就有一个单独的配置文件,这样,每一个MySQL服务之间就被分割开了,单独的修改配置,不会对其它服务造成影响,以此降低耦合。
直接删除原先的 mysql ,新建安装,将 my.cnf 内容拆成三个配置文件 3306.cnf,3307.cnf 和 3308.cnf。
多实例配置文件
3306.cnf 配置文件添加以下内容:
[mysqld]
basedir=/opt/homebrew/opt/mysql
[mysqld_multi]
mysqld=/opt/homebrew/opt/mysql/bin/mysqld_safe
mysqladmin=/opt/homebrew/opt/mysql/bin/mysqladmin
log=/opt/homebrew/opt/mysql/data/mysql_multi.log
[mysqld3306]
mysqld=mysqld
mysqladmin=mysqladmin
datadir=/opt/homebrew/opt/mysql/data/3306/data
port=3306
socket=/opt/homebrew/opt/mysql/mysql_3306.sock
server_id=13307.cnf 配置文件添加以下内容:
[mysqld]
basedir=/opt/homebrew/opt/mysql
[mysqld_multi]
mysqld=/opt/homebrew/opt/mysql/bin/mysqld_safe
mysqladmin=/opt/homebrew/opt/mysql/bin/mysqladmin
log=/opt/homebrew/opt/mysql/data/mysql_multi.log
[mysqld3307]
mysqld=mysqld
mysqladmin=mysqladmin
datadir=/opt/homebrew/opt/mysql/data/3307/data
port=3307
socket=/opt/homebrew/opt/mysql/mysql_3307.sock
server_id=23308.cnf 配置文件添加以下内容:
[mysqld]
basedir=/opt/homebrew/opt/mysql
[mysqld_multi]
mysqld=/opt/homebrew/opt/mysql/bin/mysqld_safe
mysqladmin=/opt/homebrew/opt/mysql/bin/mysqladmin
log=/opt/homebrew/opt/mysql/data/mysql_multi.log
[mysqld3308]
mysqld=mysqld
mysqladmin=mysqladmin
datadir=/opt/homebrew/opt/mysql/data/3308/data
port=3308
socket=/opt/homebrew/opt/mysql/mysql_3308.sock
server_id=3后面的操作流程一致,只是把上文中的单个配置文件启动,调整为三个配置文件启动。
主从复制
主从复制配置文件
主库配置开启 binlog 参数
log_bin = mysql-bin完整的 my.cnf 配置文件内容如下:
[mysqld]
basedir=/opt/homebrew/opt/mysql
[mysqld_multi]
mysqld=/opt/homebrew/opt/mysql/bin/mysqld_safe
mysqladmin=/opt/homebrew/opt/mysql/bin/mysqladmin
log=/opt/homebrew/opt/mysql/data/mysql_multi.log
[mysqld3306]
mysqld=mysqld
mysqladmin=mysqladmin
datadir=/opt/homebrew/opt/mysql/data/3306/data
port=3306
socket=/opt/homebrew/opt/mysql/mysql_3306.sock
server_id=1
log_error=/opt/homebrew/opt/mysql/data/3306/data/my_error.log
character-set-server=UTF8MB4
#设置二进制日志名称为mysql-bin
log_bin=mysql-bin
#需要主从复制的数据库 ,如多个则重复配置
binlog-do-db=boot
#复制过滤:也就是指定哪个数据库不用同步(mysql库一般不同步) ,如多个则重复配置
binlog-ignore-db=mysql
#主从复制的格式(mixed,statement,row,默认格式是statement。建议是设置为row,主从复制时数据更加能够统一)
binlog_format=row
#mysql8.0以上版本通过设置全局参数binlog_expire_logs_seconds修改binlog保存时间 以秒为单位;默认2592000 30天
binlog_expire_logs_seconds=604800
[mysqld3307]
mysqld=mysqld
mysqladmin=mysqladmin
datadir=/opt/homebrew/opt/mysql/data/3307/data
port=3307
socket=/opt/homebrew/opt/mysql/mysql_3307.sock
server_id=2
log_error=/opt/homebrew/opt/mysql/data/3306/data/my_error.log
character-set-server=UTF8MB4
#设置中继日志名称为slave-relay-bin
relay_log=slave-relay-bin
replicate-do-db=boot
binlog-ignore-db=mysql
binlog_format=row
read_only=ON
binlog_expire_logs_seconds=604800
[mysqld3308]
mysqld=mysqld
mysqladmin=mysqladmin
datadir=/opt/homebrew/opt/mysql/data/3308/data
port=3308
socket=/opt/homebrew/opt/mysql/mysql_3308.sock
server_id=3
log_error=/opt/homebrew/opt/mysql/data/3306/data/my_error.log
character-set-server=UTF8MB4
#设置中继日志名称为slave-relay-bin
relay_log=slave-relay-bin
replicate-do-db=boot
binlog-ignore-db=mysql
binlog_format=row
read_only=ON
binlog_expire_logs_seconds=604800
设置完成并保存后记得重启服务。
同步账号
主库操作
主库创建从库同步账号
mysql> CREATE USER 'replication'@'%' IDENTIFIED BY '123456';赋予 REPLICATION 账号 salve 权限
mysql> GRANT REPLICATION SLAVE ON *.* TO 'replication'@'%';刷新
mysql> FLUSH PRIVILEGES;查看主库状态
mysql> show master status\G
*************************** 1. row ***************************
File: mysql-bin.000008
Position: 575
Binlog_Do_DB: boot
Binlog_Ignore_DB: mysql
Executed_Gtid_Set:
1 row in set, 1 warning (0.00 sec)从库操作
设定从主库同步
change master to
MASTER_HOST='localhost',
MASTER_PORT=3306,
MASTER_USER='replication',
MASTER_PASSWORD='123456',
MASTER_LOG_FILE='mysql-bin.000008',
MASTER_LOG_POS=575,
GET_MASTER_PUBLIC_KEY=1;从库同步开关
mysql> stop slave;
mysql> start slave;查看从库状态
mysql> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for source to send event
Master_Host: localhost
Master_User: replication
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000008
Read_Master_Log_Pos: 575
Relay_Log_File: slave-relay-bin.000002
Relay_Log_Pos: 744
Relay_Master_Log_File: mysql-bin.000008
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB: boot
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: 575
Relay_Log_Space: 954
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: 1
Master_UUID: a781c79c-bb49-11ee-a395-516e37c8480e
Master_Info_File: mysql.slave_master_info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Replica has read all relay log; waiting for more updates
Master_Retry_Count: 10
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:
Master_public_key_path:
Get_master_public_key: 0
Network_Namespace:
1 row in set, 1 warning (0.00 sec)问题
记录配置过程中可能出现的问题 Replica failed to initialize applier metadata structure from the repository
mysql> stop slave;
mysql> reset slave all;
mysql> start slave;之后再重新执行 change master to 。
Error connecting to source ‘replication@localhost:3306’. This was attempt 1/10, with a delay of 60 seconds between attempts. Message: Authentication plugin ‘caching_sha2_password’ reported error: Authentication requires secure connection.
mysql 8.0之后默认的认证方式变为caching_sha2_password;
解决方案
从库中执行,之后重新 start slave;
CHANGE MASTER TO GET_MASTER_PUBLIC_KEY=1;Plugin mysql_native_password reported: ”mysql_native_password’ is deprecated and will be removed in a future release. Please use caching_sha2_password instead’ 如果你的MySQL的用户还在使用mysql_native_password(密码插件)的认证方式,那么在MySQL更新到8.0.34后,每次数据库用户以mysql_native_password方式访问MySQL,日志就会输出mysql_native_password已经废弃,即将在未来版本移除,以caching_sha2_password替代。
通过以下 sql 查询用户密码模式
select user,host,plugin from mysql.user;旧的数据库账号,除了 MySQL 自带的账户,通过 sql 来更新认证模式和密码 密码可以和旧密码一致
ALTER USER '用户名'@'域' IDENTIFIED WITH caching_sha2_password BY '密码';MySQL 自身的账户,可以通过以下 sql 更新到 mysql_native_password 模式
update mysql.user set plugin='caching_sha2_password' where user = 'root';