Mysql备份 -----innobackupex
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)
create\insert\select(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。