Ⅰ、xtrabackup介绍
- xtrabackup只能备份innodb引擎的数据,不能备份表结构,percona开源的,强烈推荐最新版本(旧版本bug多)
- innobackupex可以备份myisam和innodb两种引擎的数据和表结构,一般用这个
- 备份时,默认读取MySQL配置文件(datadir)
Ⅱ、xtrabackup安装使用
2.1 安装
[root@VM_0_5_centos src]# yum install perl-DBD-MySQL不安装这个备份会报错：Failed to connect to MySQL server: DBI connect[root@VM_0_5_centos src]# cd /usr/local/src[root@VM_0_5_centos src]# wget https://www.percona.com/downloads/XtraBackup/Percona-XtraBackup-2.4.7/binary/tarball/percona-xtrabackup-2.4.7-Linux-x86_64.tar.gz[root@VM_0_5_centos src]# tar zxvf percona-xtrabackup-2.4.7-Linux-x86_64.tar.gz -C ..添加环境变量[root@VM_0_5_centos src]# cd ..[root@VM_0_5_centos src]# ln -s percona-xtrabackup-2.4.7-Linux-x86_64/ xtrabackup[root@VM_0_5_centos src]# echo "PATH=/usr/local/xtrabackup/bin:$PATH" >> /etc/profile[root@VM_0_5_centos src]# source /etc/profile2.2 玩一手
[root@VM_0_5_centos src]# innobackupex --compress --compress-threads=8 --stream=xbstream -S /tmp/mysql.sock --parallel=4 /data/backup/ > /data/backup/backup.xbstream建议用-S连接,默认走socket,不用-S可能报连不上常用参数：throttle指定备份时用到的iops是多少,限制速度8个压缩线程,4个备份线程
输出内容（简化）
190620 19:47:53 innobackupex: Starting the backup operationIMPORTANT: Please check that the backup run completes successfully. At the end of a successful backup run innobackupex prints "completed OK!".190620 19:47:53 version_check Connecting to MySQL server with DSN 'dbi:mysql:;mysql_read_default_group=xtrabackup;mysql_socket=/tmp/mysql.sock' as 'root' (using password: YES).190620 19:47:53 version_check Connected to MySQL server190620 19:47:53 version_check Executing a version check against the server...190620 19:47:53 version_check Done.190620 19:47:53 Connecting to MySQL server host: localhost, user: root, password: set, port: not set, socket: /tmp/mysql.sockUsing server version 5.7.20-loginnobackupex version 2.4.7 based on MySQL server 5.7.13 Linux (x86_64) (revision id: 05f1fcf)xtrabackup: uses posix_fadvise().# 连接数据库并做两次版本检查xtrabackup: cd to /mdata/mysql_test_dataxtrabackup: open files limit requested 0, set to 100001xtrabackup: using the following InnoDB configuration:xtrabackup: innodb_data_home_dir = .xtrabackup: innodb_data_file_path = ibdata1:12M:autoextendxtrabackup: innodb_log_group_home_dir = ./xtrabackup: innodb_log_files_in_group = 2xtrabackup: innodb_log_file_size = 50331648InnoDB: Number of pools: 1190620 19:47:53 >> log scanned up to (10304795)# 读取配置文件,寻找对应的文件及日志位置xtrabackup: Generating a list of tablespacesInnoDB: Allocated tablespace ID 51 for dump_test/dump_inno, old maximum was 0xtrabackup: Starting 4 threads for parallel data files transfer190620 19:47:53 [04] Compressing and streaming ./ibdata1190620 19:47:53 [03] Compressing and streaming ./dump_test/dump_inno.ibd190620 19:47:53 [03] ...done190620 19:47:53 [03] Compressing and streaming ./test/test.ibd190620 19:47:53 [02] Compressing and streaming ./test/sbtest1.ibd190620 19:47:53 [03] ...done...190620 19:47:54 >> log scanned up to (10304795)190620 19:47:54 Executing FLUSH NO_WRITE_TO_BINLOG TABLES...190620 19:47:54 Executing FLUSH TABLES WITH READ LOCK...190620 19:47:54 Starting to backup non-InnoDB tables and files190620 19:47:54 [01] Compressing and streaming ./dump_test/dump_inno.frm to <STDOUT>190620 19:47:54 [01] ...done190620 19:47:54 [01] Compressing and streaming ./dump_test/db.opt to <STDOUT>190620 19:47:54 [01] ...done...190620 19:47:55 Finished backing up non-InnoDB tables and files# 拷贝数据190620 19:47:55 [00] Compressing and streaming xtrabackup_binlog_info190620 19:47:55 [00] ...done# 获取二进制文件日志点190620 19:47:55 Executing FLUSH NO_WRITE_TO_BINLOG ENGINE LOGS...xtrabackup: The latest check point (for incremental): '10304786'190620 19:47:55 >> log scanned up to (10304795)xtrabackup: Stopping log copying thread.190620 19:47:55 Executing UNLOCK TABLES190620 19:47:55 All tables unlocked# 停止拷贝,释放锁190620 19:47:55 [00] Compressing and streaming ib_buffer_pool to <STDOUT>190620 19:47:55 [00] ...done190620 19:47:55 Backup created in directory '/data/backup'MySQL binlog position: filename 'bin.000006', position '154'190620 19:47:55 [00] Compressing and streaming backup-my.cnf190620 19:47:55 [00] ...done190620 19:47:55 [00] Compressing and streaming xtrabackup_info190620 19:47:55 [00] ...donextrabackup: Transaction log of lsn (10304786) to (10304795) was copied.190620 19:47:55 completed OK!190620 19:47:55 [00] ...done190620 19:47:55 Backup created in directory '/data/backup'MySQL binlog position: filename 'bin.000006', position '154'190620 19:47:55 [00] Compressing and streaming backup-my.cnf190620 19:47:55 [00] ...done190620 19:47:55 [00] Compressing and streaming xtrabackup_info190620 19:47:55 [00] ...donextrabackup: Transaction log of lsn (10304786) to (10304795) was copied.190620 19:47:55 completed OK!# 生成各种文件,备份结束Ⅲ、xtrabackup原理分析
3.1 xtrabackup全备步骤
| - | 操作 | 解析 |
|---|---|---|
| step1 | Connecting to MySQL server host | 连接登录 |
| step2 | using the following InnoDB configuration | 读相关配置文件 |
| step3 | start xtrabackup_log | 启用日志文件,记录redo的lsn,同时持续扫描redo log,将新产生的redo拷贝到xtrabackup_logfile |
| step4 | copy innodb tables .ibd、.ibdata1、undo logs | 拷贝innodb表的独立表空间、共享表空间、undo日志 |
| step5 | flush no_write_to_binlog tables、flush tables with read lock | 强制将commit log刷入redo防止数据丢失(5.6之前没有),锁表 |
| step6 | copy non-innodb tables .MYD、.MYI、.opt、misc files和innodb tables .frm、.opt、misc files | 拷贝myisam表相关内容和innodb表的表结构文件 |
| step7 | Get binary log position | 获取二进制日志位置点,写入到xtrabackup_binlog_info文件 |
| step8 | flush no_write_to_binlog engine logs | 将redo刷盘 |
| step9 | stopping log copying thread | 停止拷贝 |
| step10 | unlock tables | 释放锁 |
| step11 | completed OK | 生成各种文件,备份结束 |
tips：
①简单点说：一个线程备份redo,贯穿整个过程始终,另外的线程备份表空间文件,直到completed OK,备份成功
②5.6之前的xtrabackup有丢数据的风险,强烈建议使用最新版本
③和mysqldump、mydumper相比,xtrabackup备份的是结束时间点的数据(二进制文件位置点不一样),所以物理备份除了本身恢复块之外,同步也快,因为不用拉数据,做一个一小时的备份,逻辑备份需要做一个小时的数据同步,物理备份不需要
④备份过程中遇到myisam还是会阻塞,数据一致性需求
Ⅳ、xtrabackup备份恢复
4.1 查看备份文件
由于我这里用的是流文件的方式备份的,所以要先打开流文件
[root@VM_0_5_centos backup]# xbstream -x < backup.xbstream[root@VM_0_5_centos backup]# lltotal 2792drwxr-x--- 2 root root 4096 July 20 19:47 abc-rw-r----- 1 root root 417 July 20 19:47 backup-my.cnf.qp-rw-r--r-- 1 root root 1822257 July 20 19:46 backup.xbstreamdrwxr-x--- 2 root root 4096 July 20 19:47 dump_test-rw-r----- 1 root root 370 July 20 19:47 ib_buffer_pool.qp-rw-r----- 1 root root 969374 July 20 19:47 ibdata1.qpdrwxr-x--- 2 root root 4096 July 20 19:47 mysqldrwxr-x--- 2 root root 4096 July 20 19:47 performance_schemadrwxr-x--- 2 root root 12288 July 20 19:47 sysdrwxr-x--- 2 root root 4096 July 20 19:47 test-rw-r----- 1 root root 102 July 20 19:47 xtrabackup_binlog_info.qp-rw-r----- 1 root root 115 July 20 19:47 xtrabackup_checkpoints-rw-r----- 1 root root 494 July 20 19:47 xtrabackup_info.qp-rw-r----- 1 root root 391 July 20 19:47 xtrabackup_logfile.qp看到很多qp文件,是因为备份时做了压缩,我们需要将其解压[root@VM_0_5_centos backup]# for f in `find ./ -iname "*\.qp"`; do qpress -dT4 $f $(dirname $f) && rm -f $f; done[root@VM_0_5_centos backup]# lldrwxr-x--- 2 root root 4096 July 20 19:57 abc-rw-r--r-- 1 root root 427 July 20 19:57 backup-my.cnf-rw-r--r-- 1 root root 1822257 July 20 19:46 backup.xbstreamdrwxr-x--- 2 root root 4096 July 20 19:57 dump_test-rw-r--r-- 1 root root 413 July 20 19:57 ib_buffer_pool-rw-r--r-- 1 root root 12582912 July 20 19:57 ibdata1drwxr-x--- 2 root root 4096 July 20 19:57 mysqldrwxr-x--- 2 root root 12288 July 20 19:57 performance_schemadrwxr-x--- 2 root root 12288 July 20 19:57 sysdrwxr-x--- 2 root root 4096 July 20 19:57 test-rw-r--r-- 1 root root 15 July 20 19:57 xtrabackup_binlog_info-rw-r----- 1 root root 115 July 20 19:47 xtrabackup_checkpoints-rw-r--r-- 1 root root 521 July 20 19:57 xtrabackup_info-rw-r--r-- 1 root root 2560 July 20 19:57 xtrabackup_logfile可以看到,除了备份表空间等,还生成了4个文件看下4个文件
[root@VM_0_5_centos backup]# cat xtrabackup_binlog_info # 记录binlog文件名和positionbin.000006 154------[root@VM_0_5_centos backup]# cat xtrabackup_checkpoints # 记录备份过程中checkpoint、lsn信息backup_type = full-backupedfrom_lsn = 0to_lsn = 10304786last_lsn = 10304795compact = 0recover_binlog_info = 0------[root@VM_0_5_centos backup]# cat xtrabackup_info # 整个备份过程中的信息uuid = 48febc78-0012-11e8-b724-525400a4dac1name =tool_name = innobackupextool_command = --compress --compress-threads=8 --stream=xbstream -S /tmp/mysql.sock --parallel=4 ./tool_version = 2.4.7ibbackup_version = 2.4.7server_version = 5.7.20-logstart_time = 2019-06-20 19:47:51end_time = 2019-06-20 19:47:56lock_time = 0binlog_pos = filename 'bin.000006', position '154'innodb_from_lsn = 0innodb_to_lsn = 10304786partial = Nincremental = Nformat = xbstreamcompact = Ncompressed = compressedencrypted = N------xtrabackup_logfile # 持续备份的redo,直接看不了4.2 恢复一手瞅瞅
step1: 应用日志,将backup恢复[root@VM_0_5_centos mdata]# innobackupex --apply-log backupstep2：将恢复好的数据拷贝到datadir,直接move也行[root@VM_0_5_centos mdata]# innobackupex --copy-back backupstep3：修改文件属主[root@VM_0_5_centos mdata]# chown -R mysql:mysql mysql_test_datastep4：启动数据库/etc/init.d/mysql.server startStarting MySQL. SUCCESS!tips：
- 日志应用完成后,backup文件中会多出一个文件：xtrabackup_binlog_pos_innodb,记录的是用于innodb的binlog的当前position,而xtrabackup_binlog_info记录的是整个实例当前的binlog position
- 般情况下,这两个位置点是一样的,但备份时两种引擎都存在时,则有可能出现xtrabackup_binlog_info.pos > xtrabackup_binlog_pos_innodb.pos
- 所以我们一般用xtrabackup_binlog_info中的binlog position
Ⅴ、其他相关问题
5.1 增量备份
--incremental-history-name=name 可使用改参数做增量备份
但非常不建议用这个增量备份功能,性能特别差
若昨天全备100G,今天更新了30G,做增量要扫描100G文件才知道哪些页改动了,再去备份,线上很难接受
percona有个参数可以监控哪些页改动了,所以不用去扫之前的所有备份的表空间,但用的也比较少
要做增量,用二进制日志的机制来做即可
5.2 指定库表备份
同样不推荐这种玩法,强烈建议完整备份
如果实例使用的是共享表空间(ibdata),不完整备份的话,可能会遇到各种问题
比如备份了a库,没备份b库,用这个备份恢复后在b库下面创建一个和之前同名的表就创建不了
5.3 远程备份
innobackupex --compress --compress-threads=8 --stream=xbstream --user=root --parallel=4 ./ | ssh root@192.168.1.192 "xbstream -x -C /data/www/mysql/backup"