（十二）MySQL逻辑备份mysqldump

（1）简介

（2）机器损坏备份恢复

前提：需要有完全备份和增量备份（二进制日志文件）

1）备份

• 需要提前开启二进制日志

  #vim /etc/my.cnf
  log-bin=/data/mydata/mysql-bin/master
  server-id=1
  #mkdir /data/mydata/mysql-bin
  #chown -R mysql.mysql /data/mydata/mysql-bin
  #systemctl restart mysqld

• 准备数据

  mysql> create database testdb;
  mysql> create table testdb.test(id int);
  mysql> insert into testdb.test values(1);

• 完整备份

  mysqldump -uroot -pMysql@123 -A -R --single-transaction --master-data=1 --flush-logs >/backup/$(date +%F-%H)-mysql-all.sql   \\需要提前创建好备份目录

  生成目录：ll /backup/2018-04-26-00-mysql-all.sql

• 生成一些数据，用于使用二进制日志恢复

  mysql>  insert into testdb.test values(2);
  mysql> flush logs;
  mysql>  insert into testdb.test values(2);
  mysql>  insert into testdb.test values(3);
  mysql> flush logs;
  mysql>  insert into testdb.test values(4);
  mysql> flush logs;
  mysql> select * from testdb.test;
  +------+
  | id   |
  +------+
  |    1 |
  |    2 |
  |    2 |
  |    3 |
  |    4 |
  +------+

• 把二进制文件拷贝了其它目录，我这里就先放在/root目录了
  cp -ar /data/mydata/mysql-bin/ /root

• 模拟数据库故障

  rm -rf /var/lib/mysql/*
  systemctl stop mysqld 
  chown -R mysql.mysql /var/lib/mysql
  systemctl start mysqld   \\无法启动
  rm -rf /var/lib/mysql/*   \\再删除数据
  systemctl start mysqld   \\再次可以启动了
  grep "password" /var/log/mysqld.log 
  2018-04-25T10:01:13.953346Z 1 [Note] A temporary password is generated for root@localhost: 9Mf3.k)AOgEd
  mysqladmin -uroot -p'9Mf3.k)AOgEd' password 'Mysql@123';

  2）恢复：注意恢复时关闭记录二进制日志，避免产生不必要的IO操作

• 关闭记录二进制日志，完整备份恢复

  #mysqladmin  -uroot -p'Mysql@123' flush-logs
  mysql> set sql_log_bin=0;
  mysql> system mysql -uroot -predhat </backup/2018-04-26-00-mysql-all.sql

• 获取备份记录的log_file文件和pos位置点

  # grep -i change /backup/2018-04-26-00-mysql-all.sql | head -1
  CHANGE MASTER TO MASTER_LOG_FILE='master.000003', MASTER_LOG_POS=154;

• 增量备份恢复

  mysql> system mysqlbinlog --start-position=154 master.000003 master.000004 master.000005 master.000006 | mysql -uroot -p'Mysql@123'

• 验证数据

  mysql> select * from testdb.test;
  +------+
  | id   |
  +------+
  |    1 |
  |    2 |
  |    2 |
  |    3 |
  |    4 |
  +------+
  5 rows in set (0.01 sec)