(12) MySQL logical backup mysqldump

(1 Introduction

(2) Backup and recovery of damaged machines

Prerequisite: Full and incremental backups (binary log files) are required

1) Backup

• You need to enable binary logging in advance

  #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

• Prepare data

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

• full backup

  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

  Generate directory: ll /backup/2018-04-26-00-mysql-all.sql

• Generate some data for recovery using binary logs

  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 |
  +------+

• Copy the binary files to other directories, I will put them in the /root directory first
  cp -ar /data/mydata/mysql-bin/ /root

• Simulate database failure

  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) Recovery: pay attention to closing the binary log when recovering to avoid unnecessary IO operations

• Turn off the binary log, and restore the full backup

  #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

• Get the log_file file and pos location point of the backup record

  # 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;

• Incremental backup recovery

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

• verify the data

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