# Day12 传统主从复制
# 本节关键词
传统主从复制搭建传统主从复制监控
# 复制介绍
复制介绍：
将主库的DDL、DML等操作通过binlog日志，传输到复制服务器(副本)，副本进行回放这些日志，从而使得从库和主库数据保持<近似>同步的工作方式
复制架构：
1. 传统：1主1从、1主多从、级联主从、双主(逐渐淘汰)
2. 演变：(增强)半同步、过滤、延时、GTID、MTS
3. 新型：多源复制(5.7+支持)
4. MGR：组复制(5.7.17+支持)，金融级别，8.0增强(WS:WriteSets)
复制场景：
1. 备份
2. 高可用
3. 读写分离
4. "分布式"架构
5. 迁移升级
# 传统主从搭建
- 安装、配置与启动
# 主服务master_ip配置 vim /etc/my.cnf
[mysqld]
user=mysql
basedir=/usr/local/mysql
datadir=/data/3306/data
socket=/tmp/mysql.sock
log_bin=/data/3306/log/binlog
binlog_format=row
server_id=51
port=3306
secure-file-priv=/tmp
gtid-mode=off
[mysql]
socket=/tmp/mysql.sock
# 从服务slave_ip配置 vim /etc/my.cnf
[mysqld]
user=mysql
basedir=/usr/local/mysql
datadir=/data/3306/data
socket=/tmp/mysql.sock
log_bin=/data/3306/log/binlog
binlog_format=row
server_id=52
port=3306
secure-file-priv=/tmp
gtid-mode=off
[mysql]
socket=/tmp/mysql.sock
# 注意
1. server_id 不同
2. 先关闭 gtid-mode=off 模拟传统的pos复制
- 主服务器创建用户
# 用于同步 repl@'<slave_ip>'
mysql -e "create user repl@'<slave_ip>' identified with mysql_native_password by '123';grant replication slave, replication client on *.* to repl@'<slave_ip>';"
# 用于远程管理 root@'<slave_ip>'
mysql -e "create user root@'<slave_ip>' identified with mysql_native_password by '123';grant all on *.* to root@'<slave_ip>';"
# 查看
mysql -e "select user, host, plugin from mysql.user;"
- 从库备份与还原
mysqldump -uroot -p123 -h <master_ip> -P 3306 -A --master-data=2 --single-transaction -R -E --triggers > /tmp/full.sql
mysql> source /tmp/full.sql;
- 从服务器启动复制
[root@slave]# grep "\--\ CHANGE MASTER" /tmp/full.sql
-- CHANGE MASTER TO MASTER_LOG_FILE='binlog.000001', MASTER_LOG_POS=2057;
[root@slave]# mysql -e \
"CHANGE MASTER TO \
MASTER_HOST='<master_ip>', \
MASTER_USER='repl', \
MASTER_PASSWORD='123', \
MASTER_PORT=3306, \
MASTER_LOG_FILE='binlog.000001', \
MASTER_LOG_POS=2057, \
MASTER_CONNECT_RETRY=10;"
[root@slave]# mysql -e "start slave;"
[root@slave]# mysql -e "show slave status\G;" | grep "Running"
# 传统复制和GTID转换
a. 未开启 gtid_mode
mysql> select @@gtid_mode;
+-------------+
| @@gtid_mode |
+-------------+
| OFF |
+-------------+
b. 修改 enforce_gtid_consistency 保证强一致性，且观察一段时间，无错误提醒
[root@master]# mysql -e "set global enforce_gtid_consistency=warn;"
[root@slave]# mysql -e "set global enforce_gtid_consistency=warn;"
c. 修改 enforce_gtid_consistency=on
[root@master]# mysql -e "set global enforce_gtid_consistency=on;"
[root@slave]# mysql -e "set global enforce_gtid_consistency=on;"
d.修改 gtid_mode=off_permissive
新生成的事务为匿名事务，同时允许复制的事务为匿名和GTID
[root@master]# mysql -e "set global gtid_mode=off_permissive;"
[root@slave]#]# mysql -e "set global gtid_mode=off_permissive;"
e. gtid_mode=on_permissive
新生成的事务为GTID，同时允许复制的事务为匿名和GTID
[root@master]# mysql -e "set global gtid_mode=on_permissive;"
[root@slave]#]# mysql -e "set global gtid_mode=on_permissive;"
f.各从节点检查剩余事务数 0
mysql -e "show status like 'ongoing_anonymous_transaction_count';"
mysql -e "flush logs;"
g. 启用gtid_mode
mysql -e "set global gtid_mode=on;"
h. 从库切换为复制模式
mysql -e "stop slave;change master to master_auto_position=1;start slave;"
mysql -e "show slave status \G"
i. 修改配置永久有效
gtid_mode=on
enforce_gtid_consistency=true
log-slave-updates=1
# 主从复制原理
流程图
源码图
-- 保存连接主库信息存储在table中，比file较快
mysql> show variables like 'master_info_repository';
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| master_info_repository | TABLE |
+------------------------+-------+
mysql> select * from mysql.slave_master_info\G
mysql> show slave hosts;
+-----------+------+------+-----------+--------------------------------------+
| Server_id | Host | Port | Master_id | Slave_UUID |
+-----------+------+------+-----------+--------------------------------------+
| 52 | | 3306 | 51 | d5819128-5814-11ed-89f9-00163e047ddd |
+-----------+------+------+-----------+--------------------------------------+
如果想显示 Host 从库配置添加 vim /etc/my.cnf
report_host=<slave_id>
- GTID在复制中的改变
-- 新增参数 master_auto_position
change master to
user password ip port
master_auto_position=1
start slave
# 半同步复制
传统复制痛点：异步，可能导致数据不一致
单机时：redo日志成功，说明事务成功
集群时：redo和binlog日志成功，说明事务成功
# 主从复制监控
- 主库查看
mysql> show processlist;
+----+-----------------+---------------------+------+------------------+-------+-----------------------------------------------------------------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+-----------------+---------------------+------+------------------+-------+-----------------------------------------------------------------+------------------+
| 8 | repl | slave_ip:50066 | NULL | Binlog Dump GTID | 10269 | Source has sent all binlog to replica; waiting for more updates | NULL |
+----+-----------------+---------------------+------+------------------+-------+-----------------------------------------------------------------+------------------+
mysql> show slave hosts;
+-----------+---------------+------+-----------+--------------------------------------+
| Server_id | Host | Port | Master_id | Slave_UUID |
+-----------+---------------+------+-----------+--------------------------------------+
| 52 | 47.92.159.156 | 3306 | 51 | d5819128-5814-11ed-89f9-00163e047ddd |
+-----------+---------------+------+-----------+--------------------------------------+
- 从库查看
show slave status \G
*************************** 1. row ***************************
Slave_IO_State: Waiting for source to send event
Master_Host: 39.103.192.233
Master_User: repl
Master_Port: 3306
Connect_Retry: 10
Master_Log_File: binlog.000009 -- IO线程有关 已接收到binlog
Read_Master_Log_Pos: 196 -- IO线程有关 位置
Relay_Log_File: iZ8vbeb633iui3aghasnpdZ-relay-bin.000007
Relay_Log_Pos: 405
Relay_Master_Log_File: binlog.000009
Slave_IO_Running: Yes -- 必须为Yes，否则故障
Slave_SQL_Running: Yes -- 必须为Yes，否则故障
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: 196 -- SQL线程 已执行
Relay_Log_Space: 672
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 -- 故障错误提示
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 51
Master_UUID: dd07cc10-4d07-11ed-9e7c-00163e160f39
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: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set: dd07cc10-4d07-11ed-9e7c-00163e160f39:1-2 -- 已接收gtid
Executed_Gtid_Set: dd07cc10-4d07-11ed-9e7c-00163e160f39:1-2 -- 已回放gtid
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
Master_public_key_path:
Get_master_public_key: 0
Network_Namespace:
已开启GTID可关注重要参数
Retrieved_Gtid_Set: dd07cc10-4d07-11ed-9e7c-00163e160f39:1-2 -- 已接收gtid
Executed_Gtid_Set: dd07cc10-4d07-11ed-9e7c-00163e160f39:1-2 -- 已回放gtid