一，原理及介绍
〇 xtrabackup能做哪些
对InnoDB引擎的表做热备
增量备份
流压缩传输到另外的服务器上
在线移动表
更简单的创建从库
备份时不增加服务器负载
〇 原理
备份及恢复大致涉及三个步骤：备份 -> prepare -> 恢复
备份运行时，工具会记住当时的LSN号，并打开xtrabackup_logfile，然后开始对datafile进行copy，即ibdata1及ibd文件。
复制需要一定的时间，在复制期间，如果文件被修改，工具将监视redo log file并将每一次更变记录下来，保存在xtrabackup_logfile中。
接下来处理非事务表如MyISAM的备份操作，innobackupex通过FLUSH TABLES WITH READ LOCK来阻塞DML。
并在此时获取binlog的position[和GTID]（此处我理解为和mysqldump --single-transaction处理方式类似）
在做完非事务表的copy之后，执行UNLOCK TABLES，完成备份，并停止记录xtrabackup_logfile。
接下来就是需要做prepare的过程，该过程类似InnoDB的crash-recovery。
对redo log进行前滚（到数据文件），并将没提交的事务进行回滚操作（rollback），这样便可以保证数据的一致性，所以对于事务表，整个过程是不会影响写操作的。
注：InnoDB、XtraDB、MyISAM是肯定支持的，其他的存储引擎没有测过。
〇 权限需求
对datadir需要有rwx的权限。
MySQL：
最小所需要的权限有：
RELOAD
LOCK TABLES（如果加上--no-lock的话可以不要）
REPLICATION CLIENT（为了获得binary log的position）
PROCESS（为了执行show engine innodb status，并且需要查看所有运行的线程）
其他可能需要用到的权限：
CREATE TABLESPACE（如果需要通过5.6+ 的TTS恢复/迁移单个表的话）
SUPER（可能需要在复制环境里启动或者停止slave线程）
CREATEINSERTSELECT（对PERCONA_SCHEMA.xtrabackup_history进行操作）
二、下载安装
官方地址：https://www.percona.com/downloads/XtraBackup/LATEST/
安装：
tar xf Percona-XtraBackup-2.4.12-r170eb8c-el7-x86_64-bundle.tar
rpm -vih percona-xtrabackup*.rpm 或者yum install -y percona-xtrabackup-*
三，全量备份与恢复
•备份数据
语法：innobackupex [--defaults-file=/etc/my.cnf] --user=DBUSER --password=DBUSERPASS [--socket=/var/lib/mysql/mysql.sock --port=3306] /path/to/BACKUP-DIR/
[root@Server data]# innobackupex --defaults-file=/etc/my.cnf --user=root --password=939879412 /data/ xtrabackup: recognized server arguments: --datadir=/var/lib/mysql --log_bin=server-bin.log --server-id=1 xtrabackup: recognized client arguments: --datadir=/var/lib/mysql --log_bin=server-bin.log --server-id=1 181029 14:41:49 innobackupex: Starting the backup operation IMPORTANT: Please check that the backup run completes successfully. At the end of a successful backup run innobackupex prints "completed OK!". 181029 14:41:50 version_check Connecting to MySQL server with DSN 'dbi:mysql:;mysql_read_default_group=xtrabackup' as 'root' (using passw ord: YES).181029 14:41:50 version_check Connected to MySQL server 181029 14:41:50 version_check Executing a version check against the server... 181029 14:41:50 version_check Done. 181029 14:41:50 Connecting to MySQL server host: localhost, user: root, password: set, port: not set, socket: not set Using server version 5.6.41 innobackupex version 2.4.12 based on MySQL server 5.7.19 Linux (x86_64) (revision id: 170eb8c) xtrabackup: uses posix_fadvise(). xtrabackup: cd to /var/lib/mysql xtrabackup: open files limit requested 0, set to 65535 xtrabackup: using the following InnoDB configuration: xtrabackup: innodb_data_home_dir = . xtrabackup: innodb_data_file_path = ibdata1:12M:autoextend xtrabackup: innodb_log_group_home_dir = ./ xtrabackup: innodb_log_files_in_group = 2 xtrabackup: innodb_log_file_size = 50331648 InnoDB: Number of pools: 1 181029 14:41:50 >> log scanned up to (2048699761) xtrabackup: Generating a list of tablespaces InnoDB: Allocated tablespace ID 4 for mysql/slave_master_info, old maximum was 0 181029 14:41:51 [01] Copying ./ibdata1 to /data/2018-10-29_14-41-49/ibdata1 181029 14:41:51 >> log scanned up to (2048699761) 181029 14:41:52 >> log scanned up to (2048699952) 181029 14:41:53 >> log scanned up to (2048700648) 181029 14:41:54 >> log scanned up to (2048700949) 181029 14:41:55 >> log scanned up to (2048701233) 181029 14:41:56 >> log scanned up to (2048701233) 181029 14:41:57 >> log scanned up to (2048701533) 181029 14:41:58 >> log scanned up to (2048701928) ......... 181029 14:42:09 Finished backing up non-InnoDB tables and files 181029 14:42:09 Executing FLUSH NO_WRITE_TO_BINLOG ENGINE LOGS... xtrabackup: The latest check point (for incremental): '2048706153' xtrabackup: Stopping log copying thread. .181029 14:42:09 >> log scanned up to (2048706153) 181029 14:42:09 Executing UNLOCK TABLES 181029 14:42:09 All tables unlocked 181029 14:42:09 Backup created in directory '/data/2018-10-29_14-41-49/' 181029 14:42:09 [00] Writing /data/2018-10-29_14-41-49/backup-my.cnf 181029 14:42:09 [00] ...done 181029 14:42:09 [00] Writing /data/2018-10-29_14-41-49/xtrabackup_info 181029 14:42:09 [00] ...done xtrabackup: Transaction log of lsn (2048670711) to (2048706153) was copied. 181029 14:42:10 completed OK!
当出现innobackupex: completed OK!
出现上面的信息，表示备份已经ok。
查看备份的结果
[root@Server data]# ll total 4 drwxr-x--- 7 root root 4096 Oct 29 14:42 2018-10-29_14-41-49 [root@Server data]# cd 2018-10-29_14-41-49/ [root@Server 2018-10-29_14-41-49]# ls backup-my.cnf ibdata1 mysql performance_schema test test1 xtrabackup_checkpoints xtrabackup_info xtrabackup_logfile zabbix
将数据库备份到远程目录
前提条件：
a.远程机器的目录要存在，同时保证是空目录。远程机器目录非空，备份时报以下错误"xtrabackup: Error writing file 'UNOPENED' (Errcode: 32 - Broken pipe)"
b.ssh要能连接：使用ssh秘钥免密码输入
innobackupex --user=USER --password=PASSWD --socket=/var/lib/mysql/mysql.sock --port=3306 --stream=tar /data/temp/ | gzip | ssh root@远程主机host "cat -> /data/temp/mysql_full_backup_2018-10-29.tar.gz"
在备份的文件夹中，有几个文件值得注意：
xtrabackup_binlog_pos_innodb记录了binlog的position，若开启了GTID，也会将GTID取出。
在用于备份+binlog恢复或建立slave的场景里十分有用。
xtrabackup_checkpoints记录了此次备份的类型和lsn号的起始值，是否压缩等
xtrabackup_info则记录了备份工具的信息，时间，备份对象（是针对全实例还是某库表），是否是增量，binlog位置等
backup-my.cnf文件，则记录了备份时可能涉及到的选项参数，比如系统表空间信息，独立undo表空间信息，redo-log信息等
• 恢复数据
注意：恢复之前
1）要先关闭数据库
2）要删除数据文件和日志文件（也可以mv移到别的地方，只要确保清空mysql数据存放目录就行）
apply-log 类似innodb的crash recovery
[root@Server data]# innobackupex --apply-log /data/2018-10-29_14-41-49/ #prepare过程 xtrabackup: recognized server arguments: --innodb_checksum_algorithm=innodb --innodb_log_checksum_algorithm=innodb --innodb_data_file_path= ibdata1:12M:autoextend --innodb_log_files_in_group=2 --innodb_log_file_size=50331648 --innodb_fast_checksum=0 --innodb_page_size=16384 --innodb_log_block_size=512 --innodb_undo_directory=. --innodb_undo_tablespaces=0 --server-id=1 --redo-log-version=0 xtrabackup: recognized client arguments: --innodb_checksum_algorithm=innodb --innodb_log_checksum_algorithm=innodb --innodb_data_file_path= ibdata1:12M:autoextend --innodb_log_files_in_group=2 --innodb_log_file_size=50331648 --innodb_fast_checksum=0 --innodb_page_size=16384 --innodb_log_block_size=512 --innodb_undo_directory=. --innodb_undo_tablespaces=0 --server-id=1 --redo-log-version=0 181029 14:50:05 innobackupex: Starting the apply-log operation IMPORTANT: Please check that the apply-log run completes successfully. At the end of a successful apply-log run innobackupex prints "completed OK!". innobackupex version 2.4.12 based on MySQL server 5.7.19 Linux (x86_64) (revision id: 170eb8c) xtrabackup: cd to /data/2018-10-29_14-41-49/ xtrabackup: This target seems to be not prepared yet. InnoDB: Number of pools: 1 xtrabackup: xtrabackup_logfile detected: size=8388608, start_lsn=(2048670711) xtrabackup: using the following InnoDB configuration for recovery: xtrabackup: innodb_data_home_dir = . xtrabackup: innodb_data_file_path = ibdata1:12M:autoextend xtrabackup: innodb_log_group_home_dir = . xtrabackup: innodb_log_files_in_group = 1 xtrabackup: innodb_log_file_size = 8388608 xtrabackup: using the following InnoDB configuration for recovery: xtrabackup: innodb_data_home_dir = . xtrabackup: innodb_data_file_path = ibdata1:12M:autoextend xtrabackup: innodb_log_group_home_dir = . xtrabackup: innodb_log_files_in_group = 1 xtrabackup: innodb_log_file_size = 8388608 xtrabackup: Starting InnoDB instance for recovery. xtrabackup: Using 104857600 bytes for buffer pool (set by --use-memory parameter) InnoDB: PUNCH HOLE support available InnoDB: Mutexes and rw_locks use GCC atomic builtins InnoDB: Uses event mutexes InnoDB: GCC builtin __sync_synchronize() is used for memory barrier InnoDB: Compressed tables use zlib 1.2.3 InnoDB: Number of pools: 1 InnoDB: Using CPU crc32 instructions InnoDB: Initializing buffer pool, total size = 100M, instances = 1, chunk size = 100M InnoDB: Completed initialization of buffer pool InnoDB: page_cleaner coordinator priority: -20 InnoDB: Highest supported file format is Barracuda. InnoDB: Log scan progressed past the checkpoint lsn 2048670711 InnoDB: Doing recovery: scanned up to log sequence number 2048706153 (0%) InnoDB: Database was not shutdown normally! InnoDB: Starting crash recovery. InnoDB: Starting an apply batch of log records to the database... InnoDB: Progress in percent: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 InnoDB: Apply batch completed InnoDB: xtrabackup: Last MySQL binlog file position 11989, file name ./server-bin.000044 InnoDB: Creating shared tablespace for temporary tables InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ... InnoDB: File './ibtmp1' size is now 12 MB. InnoDB: 96 redo rollback segment(s) found. 1 redo rollback segment(s) are active. InnoDB: 32 non-redo rollback segment(s) are active. InnoDB: Waiting for purge to start InnoDB: 5.7.19 started; log sequence number 2048706153 InnoDB: xtrabackup: Last MySQL binlog file position 11989, file name ./server-bin.000044 xtrabackup: starting shutdown with innodb_fast_shutdown = 1 InnoDB: FTS optimize thread exiting. InnoDB: Starting shutdown... InnoDB: Shutdown completed; log sequence number 2048707915 InnoDB: Number of pools: 1 xtrabackup: using the following InnoDB configuration for recovery: xtrabackup: innodb_data_home_dir = . xtrabackup: innodb_data_file_path = ibdata1:12M:autoextend xtrabackup: innodb_log_group_home_dir = . xtrabackup: innodb_log_files_in_group = 2 xtrabackup: innodb_log_file_size = 50331648 InnoDB: PUNCH HOLE support available InnoDB: Mutexes and rw_locks use GCC atomic builtins InnoDB: Uses event mutexes InnoDB: GCC builtin __sync_synchronize() is used for memory barrier InnoDB: Compressed tables use zlib 1.2.3 InnoDB: Number of pools: 1 InnoDB: Using CPU crc32 instructions InnoDB: Initializing buffer pool, total size = 100M, instances = 1, chunk size = 100M InnoDB: Completed initialization of buffer pool InnoDB: page_cleaner coordinator priority: -20 InnoDB: Setting log file ./ib_logfile101 size to 48 MB InnoDB: Setting log file ./ib_logfile1 size to 48 MB InnoDB: Renaming log file ./ib_logfile101 to ./ib_logfile0 InnoDB: New log files created, LSN=2048707915 InnoDB: Highest supported file format is Barracuda. InnoDB: Log scan progressed past the checkpoint lsn 2048708108 InnoDB: Doing recovery: scanned up to log sequence number 2048708117 (0%) InnoDB: Database was not shutdown normally! InnoDB: Starting crash recovery. InnoDB: xtrabackup: Last MySQL binlog file position 11989, file name ./server-bin.000044 InnoDB: Removed temporary tablespace data file: "ibtmp1" InnoDB: Creating shared tablespace for temporary tables InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ... InnoDB: File './ibtmp1' size is now 12 MB. InnoDB: 96 redo rollback segment(s) found. 1 redo rollback segment(s) are active. InnoDB: 32 non-redo rollback segment(s) are active. InnoDB: Waiting for purge to start InnoDB: 5.7.19 started; log sequence number 2048708117 xtrabackup: starting shutdown with innodb_fast_shutdown = 1 InnoDB: FTS optimize thread exiting. InnoDB: Starting shutdown... InnoDB: Shutdown completed; log sequence number 2048713467 181029 14:50:09 completed OK!
当出现innobackupex: completed OK!
出现上面的信息，表示恢复已经ok。
# cp -r 2018-10-29_14-41-49/* /var/lib/mysql/ 将数据拷贝到数据库的数据目录下
也可以用此命令拷贝 innobackupex --copy-back /var/lib/mysql/
# chown mysql:mysql /var/lib/mysql/ -R
重启数据库
四，增量备份与恢复
①增备方法与全备不一样：
innobackupex --user= --password= --incremental $new_dir --incremental-basedir=$basedir
其中--incremental是本次增量备份存放目录
$new_dir是表示将增量备份出来的东西放在哪个目录
--incremental-basedir则表示，针对哪一次备份做增量备份
备份的差异在目录的xtrabackup_checkpoints中查看：
比如：
$basedir中内容：
backup_type = full-prepared
from_lsn = 0
to_lsn = 2048706153
last_lsn = 2048706153
compact = 0
recover_binlog_info = 0
$new_bkdir中内容：
backup_type = incremental
from_lsn = 2048706153
to_lsn = 2048876543
last_lsn = 2048876543
compact = 0
recover_binlog_info = 0
可以注意一下增备的from_lsn号
大于这个LSN号的页都是被变更过的，这些偏移量，也就是需要被增量备份出去的
②prepare：
prepare过程：
从第一个备份开始（也就是全量）做prepare，再将往后的增量备份依次添加到全量备份中。
注意，此处多了一个参数即--redo-only，该参数是指将已提交的事务应用，未提交的事务回滚。
此外，--incremental-dir也是在之前没有用到过的，这个参数代表需要被合并进去的增量备份目录。
注意，此处多次的增量备份是指：针对上次的增量备份做的增量。
也就是可以理解为：
全备：500GB
第一次增量备份：2GB
第二次增量备份：1GB（针对第一次增量备份的增量数据）
……
第n次
按照备份顺序做prepare，也就是prepare的顺序为：
第一次全备 -> 增量备份1 -> 增量备份2 -> ... -> 增量备份n
第一次全备的prepare：innobackup --apply-log --redo-only $basedir
第二次prepare：innobackup --apply-log --redo-only $basedir --incremental-dir=$new_dir_1（此处的$new_dir_1也就是第一次增量备份）
......
第n次prepare：innobackup --apply-log $basedir --incremental-dir=$new_dir_n（此处的$new_dir_n也就是最近也就是最后一次的增量备份
最后一次增量备份的prepare，不需要指定--redo-only
最后将增量备份和全备进行合并，将未提交的事务回滚，这个操作和全量prepare无异：
innobackup --apply-log $basedir
③恢复到datadir：
和全量无异，直接copyback就行了
innobackupex --copy-back $basedir
增量备份的prepare有点特殊，还是小结一下：
① prepare完备（加上--redo-only）
② prepare每一次增量备份到完备中，需要加上--redo-only，最后一次增量备份的prepare不需要加--redo-only
③ 对生成的最终完备做--apply-log
执行第一次增量备份之后，可以再做一次增量备份
此时有两种增量备份方法：
第一种，总是针对basedir做增量，这个方式恢复起来就特别简单了，只需要将最后一次的增量备份合并到全量备份里，就可以恢复了。
第二种，总是针对上一次的增量，做增量备份。这个方式的恢复，就要逐一合并了，也就是我上述所说看起来有点复杂的增备思路。
图示：
第一种：
总是将1月1日的全备作为basedir，所以FROM_LSN号总是5000。
第二种：
总是把上一次（最近一次）的备份作为basedir。
