实验之MySQL日志备份与恢复

       日志是mysql数据库的重要组成部分。日志文件中记录着mysql数据库运行期间发生的变化；也就是说用来记录mysql数据库的客户端连接状况、SQL语句的执行情况和错误信息等。当数据库遭到意外的损坏时，可以通过日志查看文件出错的原因，并且可以通过日志文件进行数据恢复。下面是对MYSQL日志和数据恢复的简单介绍。

一、MySQL日志

主要包含：错误日志、查询日志、慢查询日志、事务日志、二进制日志

二 、MySQL备份工具

mysqldump:逻辑备份工具 ，适用于所有引擎，可用于温备，能实现完全备份，部分备份

cp,tar等文件系统工具：物理备份工具，适用于所有存储引擎，用于冷备，能实现完全备份、部分备份

lvm2的快照：几乎热备；借助文件系统工具实现物理备份

mysqlhotcopy:几乎冷备；仅用于MyISAM存储引擎

三、由于二进制日志格外重要，所以这里介绍基于二进制的mysql备份方法

方法1、mysqldump + binlog

完全备份，通过备份二进制日志实现增量备份

命令的语法格式

mysqldump [OPTIONS] database [tables]：备份单个库，或库指定的一个或多个表

mysqldump [OPTIONS] --databases [OPTIONS] DB1 [DB2DB3...]：备份一个或多个库

mysqldump [OPTIONS] --all-databases [OPTIONS]：备份所有库

实验步骤如下：

①准备备份目录

[root@centos7 ~]# mkdir /mysqlback  创建备份目录
[root@centos7 ~]# chown -R mysql.mysql /mysqlback/ 修改权限

②准备备份数据库及表

[root@centos7 ~]# mysql -uroot -p   登录数据库
MariaDB [(none)]> create database magedu;   创建数据库
MariaDB [(none)]>use magedu;
MariaDB [magedu]> create table m26(id int not null.name char (20));  创建数据表

③进行完整备份

[root@centos7 /mysqlback]# mysqldump --database magedu --flush-log > /mysqlback/mysql-all-back-`date +%F-%T`.sql  完整数据库备份
[root@centos7 /mysqlback]# mysqldump --database magedu --flush-log > /mysqlback/mysql-magedu-back-`date +%F-%T`.sql  单个数据库备份，备份magedu数据库 
[root@centos7 /mysqlback]# ls
mysql-all-back-2017-11-16-14:47:03.sql  mysql-magedu-back-2017-11-16-14:48:44.sql

④向表中插入数据

MariaDB [(none)]> use magedu;
Database changed
MariaDB [magedu]> insert into m26 values(004,'xiaohong');
Query OK, 1 row affected (0.01 sec)
MariaDB [magedu]> insert into m26 values(005,'xiaolan'); 
Query OK, 1 row affected (0.00 sec)
MariaDB [magedu]> select * from m26;
+----+----------+
| id | name |
+----+----------+
| 1 | one |
| 2 | two |
| 3 | three |
| 4 | xiaohong |
| 5 | xiaolan |
+----+----------+

⑤进行增量备份，备份二进制日志

[root@centos7 /var/lib/mysql]# mysqlbinlog bin-log.000007  查看position(BEGIN418 COMMIT644)
[root@centos7 /var/lib/mysql]# mysqlbinlog --start-position=418 --stop-position=644 /var/lib/mysql/bin-log.000007 > /mysqlback/bin-log-`date +%F_%T`.sql  根据上面查到的position位置进行增量备份

⑥继续向数据库中插入数据，没备份直接删除数据库

MariaDB [(none)]> use magedu;
Database changed
MariaDB [magedu]> insert into m26 values(008,'liuyifei');
Query OK, 1 row affected (0.03 sec)
MariaDB [magedu]> drop database magedu;

⑦数据恢复，首先保护好最后的二进制日志，查看删除数据库之前的position值

BEGIN
/*!*/;
# at 714
#171116 15:07:56 server id 1 end_log_pos 817 Query thread_id=11 exec_time=0 error_code=0
SET TIMESTAMP=1510816076/*!*/;
insert into m26 values(008,'liuyifei')
/*!*/;
# at 817
#171116 15:07:56 server id 1 end_log_pos 844 Xid = 439
COMMIT/*!*/;
# at 844
#171116 15:08:16 server id 1 end_log_pos 929 Query thread_id=11 exec_time=0 error_code=0
SET TIMESTAMP=1510816096/*!*/;
drop database magedu

⑧将最后操作的二进制日志备份

[root@centos7 /var/lib/mysql]# mysqlbinlog --stop-position=817 /var/lib/mysql/bin-log.000007 > /mysqlback/bin-log-`date +%F-%T`.sql

⑨导入之前的所有备份

[root@centos7 /var/lib/mysql]# cd /mysqlback/
[root@centos7 /mysqlback]# ls
bin-log-2017-11-16_15:02:49.sql mysql-all-back-2017-11-16-14:47:03.sql
bin-log-2017-11-16-15:16:41.sql mysql-magedu-back-2017-11-16-14:48:44.sql
bin-log-.sql
[root@centos7 /mysqlback]# mysql -uroot -p < mysql-all-back-2017-11-16-14:47:03.sql
[root@centos7 /mysqlback]# mysql -uroot -p < mysql-magedu-back-2017-11-16-14:48:44.sql
[root@centos7 /mysqlback]# mysql -uroot -p < bin-log-2017-11-16_15\:02\:49.sql 
[root@centos7 /mysqlback]# mysql -uroot -p < bin-log-2017-11-16-15:16:41.sql

⑩查看数据库及数据（恢复成功）

[root@centos7 /mysqlback]# mysql -uroot -p
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| magedu |
| mysql |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.00 sec)
MariaDB [(none)]> use magedu;
Database changed
MariaDB [magedu]> select * from m26;
+----+----------+
| id | name |
+----+----------+
| 1 | one |
| 2 | two |
| 3 | three |
| 5 | xiaolan |
| 4 | xiaohong |
| 6 | liuyifei |
+----+----------+
6 rows in set (0.00 sec)

方法2、lbm2快照+binlog

LVM快照简单来说就是将所快照源分区一个时间点所有文件的元数据（记录数据属性的数据）进行保存，如果源文件没有改变，那么访问快照卷的相应文件则直接指向源分区的源文件，如果源文件发生改变，则快照卷中与之对应的文件不会发生改变。快照卷主要用于辅助备份文件。

实验步骤如下：

①添加一块硬盘

②并划分磁盘类型为lvm类型

[root@centos7 ~]# echo '- - -' >/sys/class/scsi_host/host0/s  使主机识别硬盘
[root@centos7 ~]# fdisk -l  查看是否添加成功
Disk /dev/sde: 107.4 GB, 107374182400 bytes, 209715200 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
分区
[root@centos7 ~]# fdisk /dev/sde  对磁盘进行分区
Welcome to fdisk (util-linux 2.23.2).

③对此磁盘的操作如下

[root@centos7 ~]# partprobe  重读分区表
[root@centos7 ~]# fdisk -l   查看
Device Boot Start End Blocks Id System
/dev/sde1 2048 209715199 104856576 8e Linux LVM 
[root@centos7 ~]# pvcreate /dev/sde1  初始化物理卷
Physical volume "/dev/sde1" successfully created.
[root@centos7 ~]# vgcreate myvg /dev/sde1
Volume group "myvg" successfully created
[root@centos7 ~]# lvcreate -n mydata -L 50G myvg  创建LVM卷组
Logical volume "mydata" created.
[root@centos7 ~]# mkfs.ext4 /dev/mapper/myvg-mydata 格式化分区
mke2fs 1.42.9 (28-Dec-2013
Allocating group tables: done 
Writing inode tables: done 
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done 
[root@centos7 ~]# mkdir /bak   创建一个挂载目录
[root@centos7 ~]# mount /dev/mapper/myvg-mydata /bak   挂载
[root@centos7 ~]# cd /bak
[root@centos7 /bak]# ls
lost+found

④对数据库的操作如下

[root@centos7 /bak]# systemctl stop mariadb
[root@centos7 /bak]# cd /var/lo
local/ lock/ log/ 
[root@centos7 /bak]# cd /var/lib/mysql/
[root@centos7 /var/lib/mysql]# mv * /bak
[root@centos7 /var/lib/mysql]# cd /bak
[root@centos7 /bak]# ls
aria_log.00000001 bin-log.000004 ibdata1 magedu.sql mysql-bin.000004
aria_log_control bin-log.000005 ib_logfile0 mysql mysql-bin.000005
bin-log.000001 bin-log.000006 ib_logfile1 mysql-bin.000001 mysql-bin.index
bin-log.000002 bin-log.000007 lost+found mysql-bin.000002 performance_schema
bin-log.000003 bin-log.index magedu mysql-bin.000003 test
[root@centos7 /bak]# chown mysql.mysql . -R

⑤整理

[root@centos7 /bak]# vim /etc/my.cnf
datadir=/bak  使得数据文件在逻辑卷上
[root@centos7 /bak]# systemctl start mariadb
[root@centos7 /bak]# mysql -uroot -p
MariaDB [(none)]> FLUSH TABLES WITH READ LOCK;  锁定表
Query OK, 0 rows affected (0.00 sec)
[root@centos7 /bak]# lvcreate -L 1G -n mydata-snap -p r -s /dev/mapper/myvg-mydata  创建快照卷
Using default stripesize 64.00 KiB.
Logical volume "mydata-snap" created.
[root@centos7 /bak]# mysql -uroot -p
MariaDB [(none)]> UNLOCK TABLES;  解锁所有表
Query OK, 0 rows affected (0.00 sec)
[root@centos7 /bak]# mkdir /snap
[root@centos7 /bak]# mount /dev/mapper/myvg-mydata /snap  挂载快照卷
[root@centos7 /bak]# cd /snap/
[root@centos7 /snap]# ls （这里是存储的元数据，真实的数据存储在/bak下）
aria_log.00000001 bin-log.000004 bin-log.index magedu mysql-bin.000003 test
aria_log_control bin-log.000005 ibdata1 magedu.sql mysql-bin.000004
bin-log.000001 bin-log.000006 ib_logfile0 mysql mysql-bin.000005
bin-log.000002 bin-log.000007 ib_logfile1 mysql-bin.000001 mysql-bin.index
bin-log.000003 bin-log.000008 lost+found mysql-bin.000002 performance_schema

⑥打包备份并删库

[root@centos7 /snap]# tar -cjvf mysql-backup.tar.gz ./*  打包物理备份
[root@centos7 /snap]# cd /bak
[root@centos7 /bak]# mv mysql-backup.tar.gz /root
[root@centos7 /bak]# rm -rf * （删除bak下的数据，snap里也没有了）
[root@centos7 /bak]# ls
[root@centos7 /bak]# cd /snap/
[root@centos7 /snap]# ls
[root@centos7 /snap]# cd /bak
[root@centos7 /bak]# mv /root/mysql-backup.tar.gz ./
[root@centos7 /bak]# ls
mysql-backup.tar.gz
[root@centos7 /bak]# tar -xvf mysql-backup.tar.gz
[root@centos7 /bak]# ls （bak和snap里的数据都恢复了）
aria_log.00000001 bin-log.000005 ib_logfile0 mysql-backup.tar.gz mysql-bin.index
aria_log_control bin-log.000006 ib_logfile1 mysql-bin.000001 performance_schema
bin-log.000001 bin-log.000007 lost+found mysql-bin.000002 test
bin-log.000002 bin-log.000008 magedu mysql-bin.000003
bin-log.000003 bin-log.index magedu.sql mysql-bin.000004
bin-log.000004 ibdata1 mysql mysql-bin.000005
[root@centos7 /bak]# cd /snap/
[root@centos7 /snap]# ls
aria_log.00000001 bin-log.000005 ib_logfile0 mysql-backup.tar.gz mysql-bin.index
aria_log_control bin-log.000006 ib_logfile1 mysql-bin.000001 performance_schema
bin-log.000001 bin-log.000007 lost+found mysql-bin.000002 test
bin-log.000002 bin-log.000008 magedu mysql-bin.000003
bin-log.000003 bin-log.index magedu.sql mysql-bin.000004
bin-log.000004 ibdata1 mysql mysql-bin.000005

⑦测试

[root@centos7 /snap]# systemctl start mariadb
[root@centos7 /snap]# mysql -uroot -p （数据库都回来了）
Enter password: 
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 4
Server version: 5.5.52-MariaDB MariaDB Server
Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> use magedu;
Database changed
MariaDB [magedu]> select * from m26;
+----+----------+
| id | name |
+----+----------+
| 1 | one |
| 2 | two |
| 3 | three |
| 5 | xiaolan |
| 4 | xiaohong |
| 5 | xiaolan |
| 9 | aodaili |
+----+----------+
7 rows in set (0.07 sec)

 总结：数据无价，学好备份与恢复很重要！！