linux能关,不能打开slave

Posted 2023-03-20

参考技术A g模式怎不能打开的这种情况主要有以下原因造成：

1、两个硬盘可能都设置成的是SLAVE模式，你将两个硬盘设置成一个MASTER、一个SLAVE模式就可以了。

2、可能有一个硬盘信号线没插好，系统未检测到。

3、你的某个硬盘可能容量太大，系统不支持。

Linux下MySQL 5.7 主从复制(主从同步)

1、说明：

首先要准备两台服务器，一台主服务器(Master)，另一台从服务器(Slave)，然后要保证Master与Slave的版本要相同且Master不能高于Slave的版本，一般稳健的做法都是使其版本相同，因为MySQL不同版本之间的binlog(二进制日志)格式可能会不一样，最后会导致同步出现异常。

IP	主机名	角色
192.168.1.101	MySQL-001	master
192.168.1.102	MySQL-002	slave

版本：

系统：CentOS 6. 或 7.
MySQL版本：5.7

2、master配置文件设置如下

一般mysql配置文件在/etc/my.cnf

(如果找不到的话也有可能在这些目录下：/etc/mysql/my.cnf，/usr/local/mysql/etc/my.cnf，~/.my.cnf)

[[email protected] ~]# vim /etc/my.cnf
[mysqld]
basedir=/usr/local/mysql
datadir=/data/mysqldata
socket=/tmp/mysql.sock
user=mysql
port=3306

# master的配置
server-id=1             # 服务器id (主从必须不一样)
binlog-do-db=employees  # 要给从机同步的库
binlog-ignore-db=mysql  # 不给从机同步的库(多个写多行)
binlog-ignore-db=information_schema
binlog-ignore-db=performance_schema
binlog-ignore-db=sys
log-bin=mysql-bin       # 打开日志(主机需要打开)，这个mysql-bin也可以自定义；
expire_logs_days=90     # 自动清理 90 天前的log文件,可根据需要修改

重启数据库使配置生效：
CentOS 6.*：

[[email protected] ~]# service mysqld restart 
[[email protected] ~]# service mysqld status
 SUCCESS! MySQL running (15607)

CentOS 7.*：

[[email protected] ~]# systemctl restart  mysqld.service
[[email protected] ~]# systemctl status mysqld.service
mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled)
   Active: active (running) since 四 2018-05-17 11:42:02 CST; 2h 5min ago
     Docs: man:mysqld(8)
        http://dev.mysql.com/doc/refman/en/using-systemd.html
 Main PID: 29959 (mysqld)
   CGroup: /system.slice/mysqld.service
       └─29959 /opt/mysql/bin/mysqld --defaults-file=/etc/my.cnf

5月 17 11:42:02 tcloud-118 systemd[1]: Started MySQL Server.

测试log_bin是否成功开启

[[email protected] ~]# mysql -uroot -p
mysql> show variables like ‘%log_bin%‘;
+---------------------------------+---------------------------------+
| Variable_name                   | Value                           |
+---------------------------------+---------------------------------+
| log_bin                         | ON                              |
| log_bin_basename                | /opt/mysql/logs/mysql-bin       |
| log_bin_index                   | /opt/mysql/logs/mysql-bin.index |
| log_bin_trust_function_creators | ON                              |
| log_bin_use_v1_row_events       | OFF                             |
| sql_log_bin                     | ON                              |
+---------------------------------+---------------------------------+
6 rows in set (0.00 sec)

mysql>

可以看到log_bin为ON；

3、master的数据库中建立主从同步账号backup：

backup为用户名，192.168.1.%表示只允许192.168.1网段的客户端连接，123456为密码；

mysql> grant replication slave on *.* to ‘backup‘@‘192.168.1.%‘ identified by ‘123456‘;   # 创建同步账户
mysql> flush privileges;                                                                  # 刷新权限
mysql> select Host,User,authentication_string from mysql.user;                            # 检查是否创建
+--------------+---------------+-------------------------------------------+
| Host         | User          | authentication_string                     |
+--------------+---------------+-------------------------------------------+
| localhost    | root          | *6C362347EBEAA7DF44F6D34884615A35095E80EB |
| localhost    | mysql.session | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| localhost    | mysql.sys     | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| 192.168.1.%  | backup        | *9BB58B7F11A03B83C396FF506F3DF45727E79614 |
+--------------+---------------+-------------------------------------------+
5 rows in set (0.00 sec)

mysql>

[email protected]%账户已建立；

4、Master锁表，往slave拷贝数据

重启MySQL服务并设置读取锁定，读取锁定的意思是只能读取，不能更新，以便获得一个一致性的快照；

mysql> flush table with read lock;     # 主库锁表；默认28800秒，即8小时自动解锁；
mysql> show master status G
*************************** 1. row ***************************
             File: mysql-bin.000002
         Position: 1621
     Binlog_Do_DB:
 Binlog_Ignore_DB: mysql
Executed_Gtid_Set: 1d3d078c-59a7-11e8-9a08-00163e000b3f:1-7
1 row in set (0.00 sec)

mysql>

查看主服务器上当前的二进制日志名和偏移量值这里的file 和position 要和上面的一致；
导出master(192.168.1.101)上的数据，然后导入slave 中

master：
格式：mysqldump -uUSER -pPASSWORD DATABASE TABLE > NAME.sql

[[email protected] ~]# mysqldump -uroot -p employees > /opt/employees.sql    # 假如employees为主库已经存在的库
[[email protected] ~]# yum install openssh-clients -y                        # 可选
[[email protected] ~]# scp /opt/employees.sql [email protected]:/opt/

slave：

[[email protected] ~]# yum install openssh-clients -y                        # 可选

5、配置slave(192.168.1.102)

[[email protected] ~]# vim /etc/my.cnf
[mysqld]
basedir=/usr/local/mysql    # mysql程序路径
datadir=/data/mysqldata     # mysql数据目录
socket=/tmp/mysql.sock
user=mysql
port=3306

# slave配置
server-id=2                 # MySQLid 后面2个从服务器需设置不同
skip_slave_start=1          # 复制进程不会随着数据库的启动而启动,重启数据库后需手动启动；
#加上以下参数可以避免更新不及时，SLAVE 重启后导致的主从复制出错。
read_only = 1               # 从库普通账户只读；
master_info_repository=TABLE
relay_log_info_repository=TABLE
#relay_log_recovery=1       # 从机禁止写
#super_read_only=1          # 从机禁止写

重启数据库

CentOS 6.*：

[[email protected] ~]# service mysqld restart 
[[email protected] ~]# service mysqld status
 SUCCESS! MySQL running (15604)

CentOS 7.*：

[[email protected] ~]# systemctl restart mysqld.service
[[email protected] ~]# systemctl status mysqld.service
mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled)
   Active: active (running) since 四 2018-05-17 11:42:02 CST; 2h 5min ago
     Docs: man:mysqld(8)
        http://dev.mysql.com/doc/refman/en/using-systemd.html
 Main PID: 29959 (mysqld)
   CGroup: /system.slice/mysqld.service
       └─29959 /opt/mysql/bin/mysqld --defaults-file=/etc/my.cnf

5月 17 11:42:02 tcloud-118 systemd[1]: Started MySQL Server.

然后导入到mysql数据库中，slave上的employees数据库不存在则先创建，然后再导入

[[email protected] ~]# mysql -uroot -p
mysql> create database employees;        # 新建这个库
[[email protected] ~]# mysql -uroot -p employees < /opt/employees.sql

登录slave数据库，并做如下设置

[[email protected] ~]# mysql -uroot -p
mysql> stop slave;                  # 关闭slave同步，第一次可略过；
mysql> change master to
-> master_host=‘192.168.1.101‘,     # master的ip
-> master_user=‘backup‘,            # 备份用户名
-> master_password=‘123456‘,        # 密码
-> master_log_file=‘mysql-bin.000002‘,    # 上面截图，且要与master的参数一致
-> master_log_pos=1621;              # 上面截图，且要与master的参数一致

合写为：

mysql> change master to master_host=‘192.168.1.101‘, master_user=‘backup‘, master_password=‘123456‘, master_log_file=‘mysql-bin.000002‘, master_log_pos=1621;
mysql> start slave;                 # 启动同步
mysql> show slave status G         # 查看slave从机的状态
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.1.101
                  Master_User: backup
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000002
          Read_Master_Log_Pos: 1621
               Relay_Log_File: relay-bin.000002
                Relay_Log_Pos: 320
        Relay_Master_Log_File: mysql-bin.000002
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB:
          Replicate_Ignore_DB: mysql
           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: 1621
              Relay_Log_Space: 521
              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_UUID: 1d3d078c-59a7-11e8-9a08-00163e000b3f
             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: 5037e479-59a7-11e8-a35b-00163e000402:1-3
                Auto_Position: 0
         Replicate_Rewrite_DB:
                 Channel_Name:
           Master_TLS_Version:
1 row in set (0.00 sec)

mysql>

下面对应参数相同代表设置成功，0延时；

Slave_IO_Running: Yes

Slave_SQL_Running: Yes

Seconds_Behind_Master: 0

6、关闭掉主数据库的读取锁定,并测试

mysql> unlock tables;

在marster中创建一个新表再查看slave中是否有数据

master:

mysql> use employees;
mysql> create table test001(id int auto_increment primary key,name varchar(20) not null);
mysql> insert into test001 values(null,‘will‘);
mysql> insert into test001 values(null,‘jim‘);
mysql> insert into test001 values(null,‘tom‘);
mysql> select * from employees.test001;
+----+------+
| id | name |
+----+------+
|  1 | will |
|  2 | jim  |
|  3 | tom  |
+----+------+
3 rows in set (0.01 sec)

slave:

mysql> use employees;
mysql> select * from employees.test001;
+----+------+
| id | name |
+----+------+
|  1 | will |
|  2 | jim  |
|  3 | tom  |
+----+------+

测试2：重启关闭从数据库，主删除test001表，然后主从数据库都重启看是否正常

master:

mysql> drop table employees.test001;

slave:

mysql> use employees;
mysql> show tables;

以上实验证明主从同步成功！！！