准备一个干净的备份目录；
[root@mysql ~]$ll /backups/
total 0
MariaDB [(none)]> show binary logs;
+------------------+-----------+
| Log_name | File_size |
+------------------+-----------+
| mysql-bin.000001 | 30331 |
| mysql-bin.000002 | 1038814 |
| mysql-bin.000003 | 7698 |
| mysql-bin.000004 | 442 |
| mysql-bin.000005 | 423 |
+------------------+-----------+
5 rows in set (0.00 sec)数据备份：
默认就是以root用户的身份进行的备份；
[root@mysql ~]$innobackupex --user=root /backups/
[root@mysql ~]$ll /backups/
total 0
drwxr-x--- 6 root root 217 Feb 25 14:14 2018-02-25_14-14-07
[root@mysql ~]$ll /backups/2018-02-25_14-14-07/
total 18460
-rw-r----- 1 root root 417 Feb 25 14:14 backup-my.cnf
drwxr-x--- 2 root root 272 Feb 25 14:14 hellodb
-rw-r----- 1 root root 18874368 Feb 25 14:14 ibdata1
drwxr-x--- 2 root root 4096 Feb 25 14:14 mysql
drwxr-x--- 2 root root 4096 Feb 25 14:14 performance_schema
drwxr-x--- 2 root root 20 Feb 25 14:14 test
-rw-r----- 1 root root 21 Feb 25 14:14 xtrabackup_binlog_info
-rw-r----- 1 root root 113 Feb 25 14:14 xtrabackup_checkpoints
-rw-r----- 1 root root 454 Feb 25 14:14 xtrabackup_info
-rw-r----- 1 root root 2560 Feb 25 14:14 xtrabackup_logfile
[root@mysql ~]$cd /backups/2018-02-25_14-14-07/
[root@mysql 2018-02-25_14-14-07]$ls
backup-my.cnf ibdata1 performance_schema xtrabackup_binlog_info xtrabackup_info
hellodb mysql test xtrabackup_checkpoints xtrabackup_logfile
[root@mysql 2018-02-25_14-14-07]$
# lsn是日志序列号，在磁盘上保存了数据库的所有数据；文件很大，分成很多的小块存储在了磁盘上；
每个数据块的小块都有所谓的lsn号；如从100-200，如果将100这个数据块中的数据做了修改，那么他的LSN会加1，即
变为了201；所以根据LSN的大小，可以判断数据块中的数据是否备份过；
这里是全备份，所以就是将所有的LSN对应的数据块的数据都进行了备份。
[root@mysql 2018-02-25_14-14-07]$less xtrabackup_checkpoints
backup_type = full-backuped
from_lsn = 0
to_lsn = 1640915
last_lsn = 1640915
compact = 0
recover_binlog_info = 0
尽管表面来看是拷贝的文件，但是底层实际拷贝的是数据块，所有效率很高。
这个文件中显示的是全备份备份到二进制文件的哪个位置；
[root@mysql 2018-02-25_14-14-07]$cat xtrabackup_binlog_info
mysql-bin.000005 423
[root@mysql 2018-02-25_14-14-07]$file xtrabackup_logfile
xtrabackup_logfile: data还原数据到一个新的MySQL主机上
找一个干净的主机，将在27.7主机上备份的数据在27.17上实现还原；
[root@mysql17 ~]$vim /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
log_bin
innodb_file_per_table
[root@mysql17 ~]$yum install percona-xtrabackup-24-2.4.9-1.el7.x86_64.rpm
[root@mysql backups]$scp -rp /backups/2018-02-25_14-14-07/ 192.168.27.17:/app/
[root@mysql17 ~]$ls /app/
2018-02-25_14-14-07数据库的整理操作：
包括将不完整的事务进行回滚；因为备份的时间点极有可能被一个事务横跨；
[root@mysql17 ~]$innobackupex --apply-log /app/2018-02-25_14-14-07/
180225 01:53:05 completed OK!
确保要恢复的数据库的数据目录是空的；
[root@mysql17 ~]$ll /var/lib/mysql/
total 0
将整理过数据复制到数据库的数据目录；
这个过程就是复制数据，对于innodb引擎，他是基于块的方式实现的；对于myISAM引擎，
那么就是单个文件的复制；
[root@mysql17 ~]$innobackupex --copy-back /app/2018-02-25_14-14-07/
...
180225 01:56:10 completed OK!
[root@mysql17 ~]$ll /var/lib/mysql/
total 40976
drwxr-x--- 2 root root 272 Feb 25 01:56 hellodb
-rw-r----- 1 root root 18874368 Feb 25 01:56 ibdata1
-rw-r----- 1 root root 5242880 Feb 25 01:56 ib_logfile0
-rw-r----- 1 root root 5242880 Feb 25 01:56 ib_logfile1
-rw-r----- 1 root root 12582912 Feb 25 01:56 ibtmp1
drwxr-x--- 2 root root 4096 Feb 25 01:56 mysql
drwxr-x--- 2 root root 4096 Feb 25 01:56 performance_schema
drwxr-x--- 2 root root 20 Feb 25 01:56 test
-rw-r----- 1 root root 35 Feb 25 01:56 xtrabackup_binlog_pos_innodb
-rw-r----- 1 root root 454 Feb 25 01:56 xtrabackup_info
[root@mysql17 ~]$chown -R mysql.mysql /var/lib/mysql/
[root@mysql17 ~]$ll /var/lib/mysql/
total 40976
drwxr-x--- 2 mysql mysql 272 Feb 25 01:56 hellodb
-rw-r----- 1 mysql mysql 18874368 Feb 25 01:56 ibdata1
-rw-r----- 1 mysql mysql 5242880 Feb 25 01:56 ib_logfile0
-rw-r----- 1 mysql mysql 5242880 Feb 25 01:56 ib_logfile1
-rw-r----- 1 mysql mysql 12582912 Feb 25 01:56 ibtmp1
drwxr-x--- 2 mysql mysql 4096 Feb 25 01:56 mysql
drwxr-x--- 2 mysql mysql 4096 Feb 25 01:56 performance_schema
drwxr-x--- 2 mysql mysql 20 Feb 25 01:56 test
-rw-r----- 1 mysql mysql 35 Feb 25 01:56 xtrabackup_binlog_pos_innodb
-rw-r----- 1 mysql mysql 454 Feb 25 01:56 xtrabackup_info
[root@mysql17 ~]$ll /var/lib/mysql/ -d
drwxr-xr-x 6 mysql mysql 198 Feb 25 01:56 /var/lib/mysql/[root@mysql17 ~]$systemctl start mariadb
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| hellodb |
| mysql |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.00 sec)
MariaDB [(none)]>
MariaDB [(none)]> show master logs;
+--------------------+-----------+
| Log_name | File_size |
+--------------------+-----------+
| mariadb-bin.000001 | 245 |
+--------------------+-----------+
1 row in set (0.00 sec)
MariaDB [(none)]> select * from hellodb.students;
Empty set (0.00 sec)
以上就是使用xtrabackup实现将一个主机的数据全备份后还原到一个远程的新的主机的过程。
