Linux命令：MySQL系列之十四--MySQL备份与还原（LVM逻辑卷快照备份重要章节）

通过LVM逻辑卷实现MySQL备份及还原（几乎热备）：
前提：
1、数据文件要在逻辑卷上；
2、此逻辑卷所在卷组必须有足够的空间使用快照卷；
3、数据文件和事务日志要在同一个逻辑卷上；
步骤：
1、打开会话，施加读锁，锁定所有表；
mysql> FLUSH TABLES WITH READ LOCK; #刷新表并对表施加读锁
mysql> FLUSH LOGS; #滚动日志
2、通过另一个终端，保存二进制日志文件及相关位置信息；
[root@lamp ~]# mysql -uroot -p -e 'SHOW MASTER STATUS\G' > /path/to/master.info
#不登录mysql客户端直接查看位置状态，并保存位置信息到相应目录
3、创建快照卷
[root@lamp ~]# lvcreate -L SIZE -s -p r -n LV_NAME /path/to/source_lv
#创建快照卷，-s:指定为所创建的是快照卷s=snapshot快照; -p:指定权限p=permission许可；
r:读权限;-n:指定快照名称；LV_NAME:快照名称;/path/to/source_lv:针对哪个逻辑卷目录
路径做快照;-L:指定快照卷大小。
4、释放锁
mysql> UNLOCK TABLES; #释放锁
5、挂载快照卷，并备份；
mount /dev/myvg/mydata-snap /mnt -o ro #挂载快照卷至/mnt目录，只读挂载
cp -a ./* /backup/full-backup-2017-06-06/ #挂载后把数据复制到备份目录， -a:表示
复制文件的所有属性及内容，保留源文件的所有属性及权限
6、删除快照卷
umount /mnt #备份完后卸载快照卷挂载的目录 lvremove --force /dev/myvg/mydata-snap #强制移除快照卷 rm -rf mysql-bin.* #把备份目录中的日志文件删除掉，节省空间 7、增量备份二进制日志
mysqlbinlog --start-datetime='2017-06-06 10:11:02' mysql-bin.000005 mysql-bin.000006 > /backup/incremental-`date +%F-%H-%M-%S`.sql #备份二进制日志，如果增量备份的二进制日志
含有2个或以上的日志文件，需要通过指定开始时间点来备份。

实例：通过实际操作，实现lvm逻辑卷快照备份及恢复mysql操作；
首先打开mysql客户端：
[root@lamp ~]# mysql #打开mysql客户端
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.5.28-log Source distribution
Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> FLUSH TABLES WITH READ LOCK; #首先刷新表并施加读锁
Query OK, 0 rows affected (0.00 sec)
mysql> FLUSH LOGS; #滚动日志
Query OK, 0 rows affected (0.06 sec)
mysql> SHOW MASTER STATUS; #查看二进制日志位置状态
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000005 | 107 | | |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)
不要退出或关闭此mysql客户端，重新打开一个服务器终端，执行位置信息的保存；
[root@lamp ~]# mkdir /backup #新建一个备份目录
[root@lamp ~]# mysql -e 'SHOW MASTER STATUS\G;' > /backup/master-`date +%F`.info #不登录mysql客户端，直接通过mysql -e直接编辑数据库，把查看二进制日志位置状态保存至备份目录下
[root@lamp ~]# ls /backup/
master-2017-06-06.info
对mysql数据目录执行快照（所以说通过逻辑卷备份数据库，前提必须是数据文件存放在逻辑卷上）
[root@lamp ~]# lvcreate -L 50M -s -p r -n mydata-snap /dev/myvg/mydata #对/dev/myvg/mydata逻辑卷做快照，大小为50M，-s:表示snapshot快照，-p:指定权限permission
r:读的权限read,-n:指定快照卷的名称。
Rounding up size to full physical extent 52.00 MiB
Logical volume "mydata-snap" created
[root@lamp ~]# lvs #查看逻辑卷，刚新建的快照逻辑卷
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
mydata myvg owi-ao 10.00g
mydata-snap myvg sri-a- 52.00m mydata 0.02
[root@lamp ~]# mount #查看挂载相关信息
/dev/sda7 on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0")
/dev/sda1 on /boot type ext4 (rw)
/dev/sda3 on /home type ext4 (rw)
/dev/sda5 on /tmp type ext4 (rw)
/dev/sda2 on /usr/local type ext4 (rw)
/dev/mapper/myvg-mydata on /mydata type ext4 (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
执行完快照后，即可解锁表；
mysql> UNLOCK TABLES; #解锁
Query OK, 0 rows affected (0.00 sec)
对快照进行挂载并备份；
[root@lamp ~]# mount /dev/myvg/mydata-snap /mnt -o ro #以只读方式挂载刚做的快照卷
[root@lamp ~]# cd /mnt #进入挂载目录
[root@lamp mnt]# ls
data lost+found
[root@lamp mnt]# cd data/
[root@lamp data]# ls
hellodb ib_logfile1 lamp.pid mysql-bin.000001 mysql-bin.000004 performance_schema testdb ibdata1 jiaowu mydb mysql-bin.000002 mysql-bin.000005 stu
ib_logfile0 lamp.err mysql mysql-bin.000003 mysql-bin.index test

[root@lamp data]# mkdir /backup/full-backup-`date +%F` #创建备份目录并以时间格式命名
[root@lamp data]# cp -a ./* /backup/full-backup-2017-06-06/ #-a:复制当前目录的所有内容及其权限属性到备份的目录
[root@lamp data]# cd
[root@lamp ~]# umount /mnt #卸载挂载的目录/mnt
[root@lamp ~]# lvremove --force /dev/myvg/mydata-snap #移除刚才创建的快照卷--force强制性
Logical volume "mydata-snap" successfully removed
[root@lamp ~]# cd /backup/full-backup-2017-06-06/
[root@lamp full-backup-2017-06-06]# ls
hellodb ib_logfile1 lamp.pid mysql-bin.000001 mysql-bin.000004 performance_schema testdb ibdata1 jiaowu mydb mysql-bin.000002 mysql-bin.000005 stu
ib_logfile0 lamp.err mysql mysql-bin.000003 mysql-bin.index test
[root@lamp full-backup-2017-06-06]# rm -rf mysql-bin.* #删除相关的二进制日志文件以便节省空间
[root@lamp full-backup-2017-06-06]# ls
hellodb ib_logfile0 jiaowu lamp.pid mysql stu testdb
ibdata1 ib_logfile1 lamp.err mydb performance_schema test
root@lamp ~]# cd /mydata/data
[root@lamp data]# ls
hellodb ib_logfile1 lamp.pid mysql-bin.000001 mysql-bin.000004 performance_schema testdb ibdata1 jiaowu mydb mysql-bin.000002 mysql-bin.000005 stu
ib_logfile0 lamp.err mysql mysql-bin.000003 mysql-bin.index test
[root@lamp data]# cat /backup/master-2017-06-06.info
*************************** 1. row ***************************
File: mysql-bin.000005 #记录的二进制日志文件
Position: 107 #二进制日志的位置
Binlog_Do_DB:
Binlog_Ignore_DB:
mysql> FLUSH LOGS; #滚动日志
Query OK, 0 rows affected (0.01 sec)
mysql> USE jiaowu
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> INSERT INTO tutors(Tname) VALUES ('stu0003'); #往表tutors中插入数据,字段Tname 值stu0003
Query OK, 1 row affected (0.00 sec)
mysql> INSERT INTO tutors(Tname) VALUES ('stu0004'); #往表tutors中插入数据,字段Tname 值stu0004
Query OK, 1 row affected (0.00 sec)
mysql> SHOW MASTER STATUS; #查看此时二进制日志的位置状态信息
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000006 | 575 | | |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)
mysql> \q
Bye
[root@lamp data]# mysqlbinlog --start-datetime='2017-06-06 10:11:02' mysql-bin.000005 mysql-bin.000006 > /backup/incremental-`date +%F-%H-%M-%S`.sql #导出二进制日志文件bin.000005和bin.000006时间点从2017-06-06 10:11:02开始后的内容
[root@lamp data]# ls /backup/incremental-2017-06-06-17-01-41.sql
/backup/incremental-2017-06-06-17-01-41.sql
[root@lamp data]# service mysqld stop #停止mysqld进程
Shutting down MySQL.. [ OK ]
[root@lamp data]# rm -rf ./* #模拟mysql数据库数据目录内容丢失（手动删除）
[root@lamp data]# ls #目录中的内容全部删除，查看显示为空
[root@lamp data]# cp -a /backup/full-backup-2017-06-06/* ./ #复制之前快照卷备份的内容至当前数据目录，-a:复制文件的内容及权限属性。
[root@lamp data]# ll #确保所有文件的属主为mysql用户
total 28712
drwx------. 2 mysql mysql 4096 Jun 2 15:30 hellodb
-rw-rw----. 1 mysql mysql 18874368 Jun 5 14:00 ibdata1
-rw-rw----. 1 mysql mysql 5242880 Jun 5 14:00 ib_logfile0
-rw-rw----. 1 mysql mysql 5242880 Jun 2 15:28 ib_logfile1
drwx------. 2 mysql mysql 4096 Jun 5 14:00 jiaowu
-rw-rw----. 1 mysql root 1853 Jun 2 15:28 lamp.err
-rw-rw----. 1 mysql mysql 6 Jun 2 15:28 lamp.pid
drwx------. 2 mysql mysql 4096 Jun 2 15:30 mydb
drwx------. 2 mysql root 4096 Jun 2 15:30 mysql
drwx------. 2 mysql mysql 4096 Jun 2 15:28 performance_schema
drwx------. 2 mysql mysql 4096 Jun 2 15:30 stu
drwx------. 2 mysql root 4096 Jun 2 15:28 test
drwx------. 2 mysql mysql 4096 Jun 2 15:30 testdb
[root@lamp data]# service mysqld start #开启mysqld进程
Starting MySQL [ OK ]
[root@lamp data]# mysql -uroot -p #登录mysql客户端
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.5.28-log Source distribution
Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> USE jiaowu
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 tutors; #查询tutors表的内容（此时后插入的2行数据没有）
+-----+--------------+--------+------+
| TID | Tname | Gender | Age |
+-----+--------------+--------+------+
| 1 | HongQigong | M | 93 |
| 2 | HuangYaoshi | M | 63 |
| 3 | Miejueshitai | F | 72 |
| 4 | OuYangfeng | M | 76 |
| 5 | YiDeng | M | 90 |
| 6 | YuCanghai | M | 56 |
| 7 | Jinlunfawang | M | 67 |
| 8 | HuYidao | M | 42 |
| 9 | NingZhongze | F | 49 |
+-----+--------------+--------+------+
9 rows in set (0.00 sec)
mysql> SET sql_log_bin=0; #导入二进制日志前，先关闭日志记录功能0为关闭，1为打开
Query OK, 0 rows affected (0.00 sec)
mysql> SOURCE /backup/incremental-2017-06-06-17-01-41.sql #导入备份的二进制日志数据
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
mysql> SELECT * FROM tutors; #再次查询tutors表的内容，此时后插入的2行数据已经生成
+-----+--------------+--------+------+
| TID | Tname | Gender | Age |
+-----+--------------+--------+------+
| 1 | HongQigong | M | 93 |
| 2 | HuangYaoshi | M | 63 |
| 3 | Miejueshitai | F | 72 |
| 4 | OuYangfeng | M | 76 |
| 5 | YiDeng | M | 90 |
| 6 | YuCanghai | M | 56 |
| 7 | Jinlunfawang | M | 67 |
| 8 | HuYidao | M | 42 |
| 9 | NingZhongze | F | 49 |
| 10 | stu0003 | M | NULL |
| 11 | stu0004 | M | NULL |
+-----+--------------+--------+------+
11 rows in set (0.00 sec)
mysql> SET sql_log_bin=1; #二进制日志导入后再打开二进制日志记录功能
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW MASTER STATUS; #查看此时的二进制日志位置状态信息
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000001 | 107 | | |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)
至此通过lvm逻辑卷和二进制cp功能实现了mysql数据库备份和还原。