LINUX——关于mysql中较详细的，数据库的主从配置，自动备份以及读写分离的使用

1.主从简介
数据在企业中是非常重要的一部分，存储数据的数据库多种多用样，但却都存在着一种隐患
·数据库数据丢失
·数据库访问人数较多时，一台数据库无法保证服务质量
2.主从的作用
·实时灾备，用于故障切换
·读写分离，提供查询服务
·备份，避免影响业务
3.主从形式
·一主一丛
·主主复制
·一主多从
·多主一丛
·联级复制

主从复制原理

主从复制步骤

主库将所有写的操作记录到binlog日志(二进制日志)中并生成一个log dump线程，将binlog日志传给从库的I/O线程

从库生成两个线程，一个I/O线程，一个SQL线程
·I/O线程去请求主库的binlog，并将得到的binlog日志写到relay log（中继日志）文件中
·SQl线程，会读取relay log 文件中的日志，并解析成具体操作，来实现主从的操作一致，达到最终数据一致的目的

主从复制配置步骤：
1.确保从数据库与主数据库里的数据一样
2.在主数据库创建一个同步账号授权给从数据库使用
3.配置主数据库(修改配置文件)
4.配置从数据库(修改配置文件)

配置需求：
环境介绍：搭建两台mysql服务器，一台作为主服务器，一台作为从服务器，主服务器进行写操作，从服务器进行读操作

配置信息
主数据库 ip192.168.56.11 centos7 有数据
从数据库 ip192.168.56.138 centos7 无数据

主从同步设置
防火墙设置

[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# systemctl disable firewalld
[root@localhost ~]# sed -ri 's/(SELINUX=).*/\1disabled/g' /etc/selinux/config
[root@localhost ~]# setenforce 0

下载二进制格式的mysql包

[root@localhost ~]# cd /usr/src/
[root@localhost src]# wget https://downloads.mysql.com/archives/get/file/mysql-5.7.22-linux-glibc2.12-x86_64.tar.gz
[root@localhost src]# ls
debug  kernels  mysql-5.7.22-linux-glibc2.12-x86_64.tar.gz

创建主和组

[root@localhost src]# groupadd -r mysql
[root@localhost src]# useradd -M -s /sbin/nologin -g mysql mysql
[root@localhost src]# tar xf mysql-5.7.22-linux-glibc2.12-x86_64.tar.gz -C /usr/local/
[root@localhost src]# cd /usr/local/
[root@localhost local]# ln -sv mysql-5.7.22-linux-glibc2.12-x86_64/ mysql
"mysql" -> "mysql-5.7.22-linux-glibc2.12-x86_64/"

//修改目录/usr/local/mysql的属主属组

[root@localhost local]# chown -R mysql.mysql /usr/local/mysql
[root@localhost local]# ll /usr/local/mysql -d
lrwxrwxrwx. 1 mysql mysql 36 9月   7 11:43 /usr/local/mysql -> mysql-5.7.22-linux-glibc2.12-x86_64/

//添加环境变量

[root@localhost local]# ls /usr/local/mysql
bin  COPYING  docs  include  lib  man  README  share  support-files
[root@localhost local]# echo 'export PATH=/usr/local/mysql/bin:$PATH' > /etc/profile.d/mysql.sh
[root@localhost local]# . /etc/profile.d/mysql.sh
[root@localhost local]# echo $PATH
/usr/local/mysql/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin

//建立数据存放目录

[root@localhost local]# mkdir /opt/data
[root@localhost local]# chown -R mysql.mysql /opt/data/
[root@localhost local]# ll /opt/
总用量 0
drwxr-xr-x. 2 mysql mysql 6 9月   7 11:47 data
drwxr-xr-x. 2 root  root  6 3月  26 2015 rh

//初始化数据库

[root@localhost local]# /usr/local/mysql/bin/mysqld --initialize --user=mysql --datadir=/opt/data/
2018-09-07T03:48:13.790964Z 1 [Note] A temporary password is generated for root@localhost: n*Fsa&a+O1kN  /最后会生成一个临时密码

//从：数据库初始化，前面步骤一样，所以省略

[root@localhost local]# /usr/local/mysql/bin/mysqld --initialize --user=mysql --datadir=/opt/data/
2018-09-07T06:25:11.123940Z 1 [Note] A temporary password is generated for root@localhost: QR(XhNPpk6Qi

//生成配置文件/

[root@localhost ~]# cat > /etc/my.cnf <

//配置服务启动脚本
[root@localhost ~]# cp -a /usr/local/mysql/support-files/mysql.server /etc/init.d/mysqld
[root@localhost ~]# sed -ri 's#^(basedir=).*#\1/usr/local/mysql#g' /etc/init.d/mysqld
[root@localhost ~]# sed -ri 's#^(datadir=).*#\1/opt/data#g' /etc/init.d/mysqld

//启动mysql

[root@localhost ~]# /etc/init.d/mysqld start
[root@localhost ~]# ps -ef|grep mysql
[root@localhost ~]# ss -antl
LISTEN 0 80 :::3306 :::*

//修改密码
//使用临时密码登陆

[root@localhost ~]# /usr/local/mysql/bin/mysql -uroot -p
Enter password:
mysql>
//设置新密码
mysql> set password = password('guohui123');
以上是两台数据库服务器的配置，配置方式相同

主：//查看主从库的备份

[root@localhost local]# mysql -uroot -pguohui123 -e 'show databases;'
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
创建一个库，表
mysql> use guohui
Database changed
mysql> create table student (id int(11) NOT NULL,name varchar(100) NOT NULL,age TINYINT(3));
Query OK, 0 rows affected (0.02 sec)
mysql> insert into student (id,name,age) value (1,'tom',20);
Query OK, 1 row affected (0.05 sec)
mysql> desc student;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id    | int(11)      | NO   |     | NULL    |       |
| name  | varchar(100) | NO   |     | NULL    |       |
| age   | tinyint(3)   | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
3 rows in set (0.01 sec)
mysql> select * from student;
+----+------+------+
| id | name | age  |
+----+------+------+
|  1 | tom  |   20 |
+----+------+------+
1 row in set (0.00 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| guohui             |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

主：//全备份主库
全备主库时需要另外开一个终端，给数据加上读锁，避免在备份期间有其他人在写入数据导致数据不一致，并且锁必须在备份完成后才能退出，退出则解锁

mysql> FLUSH TABLES WITH READ LOCK;
Query OK, 0 rows affected (0.01 sec)

主：//备份主库并将文件传输到从库

[root@localhost ~]# mysqldump -uroot -pguohui123 --all-databases > /opt/all-20180907-1.sql
mysqldump: [Warning] Using a password on the command line interface can be insecure.
[root@localhost ~]# ls /opt
all-20180907-1.sql  data  rh//传输
[root@localhost ~]# scp /opt/all-20180907-1.sql [email protected]:/opt/
The authenticity of host '192.168.56.138 (192.168.56.138)' can't be established.
ECDSA key fingerprint is SHA256:by
E1DjsPUpqjJssSP+RcbkM7+wcjdzMkjW3u09KrSB8.
ECDSA key fingerprint is MD5:c6:d2:a1:34:73:2f:66:c9:ac:db:ca:2b:7a:78:4f:75.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.56.138' (ECDSA) to the list of known hosts.
[email protected]'s password:1    //这里输入root密码
all-20180907-1.sql                                                  100%  783KB  19.2MB/s   00:00  
主：//接触锁表状态
mysql> quit
Bye

从：//在从库上恢复主库的备份并查看有哪些库，确保与主库一致

//查看主备传过来的文件
[root@localhost ~]# ls /opt
all-20180907-1.sql  data  rh
将文件导入从数据库
[root@localhost ~]# mysql -uroot -pguohui123 < /opt/all-20180907-1.sql
mysql: [Warning] Using a password on the command line interface can be insecure.
//查看数据库
[root@localhost ~]# mysql -uroot -pguohui123 -e 'show databases;'
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database           |
+--------------------+
| information_schema |
| guohui             |
| mysql              |
| performance_schema |
| sys                |
+--------------------+

主：//在主数据库里创建一个同步账号授权给从数据库使用

创建数据库用户guohui，密码：guohui123，只能在192.168.56.138上远程登陆
mysql> CREATE USER 'guohui'@'192.168.56.138' IDENTIFIED BY 'guohui123';
Query OK, 0 rows affected (0.00 sec)

赋予权限用户guohui，可以在192.168.56.138上访问本机所有数据库的所有表，无需密码：
mysql> GRANT REPLICATION SLAVE ON *.* TO 'guohui'@'192.168.56.138';
Query OK, 0 rows affected (0.00 sec)

重新加载特权：
mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)

mysql>

主：//配置主数据库

[root@localhost ~]# vim /etc/my.cnf
[mysqld]
basedir = /usr/local/mysql
datadir = /opt/data
socket = /tmp/mysql.sock
port = 3306
pid-file = /opt/data/mysql.pid
log-error = /opt/data/mysqld.log   //错误日志
user = mysql
skip-name-resolve
#
log-bin = mysql_bin   //启动binlog日志
server-id = 2   //数据库服务器唯一标识符，主库的server-id值必须比从库的大

启动
[root@localhost ~]# /etc/init.d/mysqld restart
ERROR! MySQL server PID file could not be found!
Starting MySQL.Logging to '/opt/data/mysqld.log'.
. SUCCESS!

查看主库状态：

mysql> show master status;
mysql_bin，文件里写的二进制文件名字
000001  版本
Position  位置 154
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql_bin.000001 |      154 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

从：//配置从数据库

[root@localhost ~]# vim /etc/my.cnf
[mysqld]
basedir = /usr/local/
mysqldatadir = /opt/data
socket = /tmp/mysql.sock
port = 3306
pid-file = /opt/data/mysql.pid
log-error = /opt/data/mysql.log
user = mysql
skip-name-resolve
#replication
server-id = 5  //设置从库的唯一标识符，从库的server-id值必须小于主库的该值
relay-log = mysql_relay_log    //启动中继日志relay-log启动

[root@localhost ~]# /etc/init.d/mysqld restart
Shutting down MySQL.. SUCCESS!
Starting MySQL.Logging to '/opt/data/mysql.log'.
SUCCESS!

从：//配置并启动主从复制

CHANGE MASTER TO                       指定的主服务器
MASTER_HOST='192.168.56.11',     指定的主服务器ip
MASTER_USER='guohui',
MASTER_PASSWORD='guohui123',  密码
MASTER_LOG_FILE='mysql-bin.000001',     二进制文件的名字与版本
MASTER_LOG_POS=154;                   位置 154

mysql> change master to master_host='192.168.56.11',master_user='guohui',master_password='guohui123',master_log_file='mysql_bin.000001',master_log_pos=154;
Query OK, 0 rows affected, 2 warnings (0.02 sec)

启动从服务的从服务
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)

从：//查看从服务器状态

mysql> show slave status \G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.56.11
                  Master_User: guohui
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql_bin.000002
          Read_Master_Log_Pos: 154
               Relay_Log_File: mysql_relay_log.000004
                Relay_Log_Pos: 367
        Relay_Master_Log_File: mysql_bin.000002
             Slave_IO_Running: Yes       //必须yes
            Slave_SQL_Running: Yes     //必须yes
mysql>

测试：
主：//在数据库中插入数据

mysql> select * from student;
+----+------+------+
| id | name | age  |
+----+------+------+
|  1 | tom  |   20 |
+----+------+------+
1 row in set (0.00 sec)

mysql> insert into student value (1,'jerry',23);
Query OK, 1 row affected (0.00 sec)

mysql> select * from student;
+----+-------+------+
| id | name  | age  |
+----+-------+------+
|  1 | tom   |   20 |
|  1 | jerry |   23 |
+----+-------+------+
2 rows in set (0.00 sec)

mysql>

从：//查看测试结果

mysql> use guohui;
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> select * from student;
+----+-------+------+
| id | name  | age  |
+----+-------+------+
|  1 | tom   |   20 |
|  1 | jerry |   23 |
+----+-------+------+
2 rows in set (0.00 sec)

mysql>

由此可见，数据库的主从功能，搭建成功