关于Xtrabackup(又或innobackupex)的介绍,详细参考官方文档

Xtrabackup安装指南

文件准备

[root@wuxiang11 ~]# cd percona-xtrabackup/
[root@wuxiang11 percona-xtrabackup]# ls
libev-4.15-1.el6.rf.x86_64.rpm  percona-release-0.1-4.noarch.rpm  percona-xtrabackup-24-2.4.4-1.el7.x86_64.rpm

开始安装依赖文件

[root@wuxiang11 percona-xtrabackup]# rpm -ivh libev-4.15-1.el6.rf.x86_64.rpm 
warning: libev-4.15-1.el6.rf.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 6b8d79e6: NOKEY
Preparing...                ########################################### [100%]
   1:libev                  ########################################### [100%]

安装-01

[root@wuxiang11 percona-xtrabackup]# rpm -ivH percona-release-0.1-4.noarch.rpm
Preparing packages for installation...
percona-release-0.1-4
[root@wuxiang11 percona-xtrabackup]# yum list | grep percona

马上就安装完成

[root@wuxiang11 percona-xtrabackup]# yum install percona-xtrabackup-24

Loaded plugins: fastestmirror, security
Setting up Install Process
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package percona-xtrabackup-24.x86_64 0:2.4.11-1.el6 will be installed
--> Processing Dependency: perl(DBD::mysql) for package: percona-xtrabackup-24-2.4.11-1.el6.x86_64
--> Running transaction check
---> Package perl-DBD-MySQL.x86_64 0:4.013-3.el6 will be installed
--> Processing Dependency: perl(DBI::Const::GetInfoType) for package: perl-DBD-MySQL-4.013-3.el6.x86_64
--> Processing Dependency: perl(DBI) for package: perl-DBD-MySQL-4.013-3.el6.x86_64
--> Processing Dependency: libmysqlclient.so.16(libmysqlclient_16)(64bit) for package: perl-DBD-MySQL-4.013-3.el6.x86_64
--> Processing Dependency: libmysqlclient.so.16()(64bit) for package: perl-DBD-MySQL-4.013-3.el6.x86_64
--> Running transaction check
---> Package Percona-Server-shared-51.x86_64 0:5.1.73-rel14.12.625.rhel6 will be installed
---> Package perl-DBI.x86_64 0:1.609-4.el6 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

===============================================================================================================================================================================================
 Package                                           Arch                            Version                                               Repository                                       Size
===============================================================================================================================================================================================
Installing:
 percona-xtrabackup-24                             x86_64                          2.4.11-1.el6                                          percona-release-x86_64                          8.1 M
Installing for dependencies:
 Percona-Server-shared-51                          x86_64                          5.1.73-rel14.12.625.rhel6                             percona-release-x86_64                          2.1 M
 perl-DBD-MySQL                                    x86_64                          4.013-3.el6                                           centos6.7_64                                    134 k
 perl-DBI                                          x86_64                          1.609-4.el6                                           centos6.7_64                                    705 k

Transaction Summary
===============================================================================================================================================================================================
Install       4 Package(s)

Total download size: 11 M
Installed size: 12 M
Is this ok [y/N]: y
Downloading Packages:
(1/4): Percona-Server-shared-51-5.1.73-rel14.12.625.rhel6.x86_64.rpm                                                                                                    | 2.1 MB     00:02     
(2/4): percona-xtrabackup-24-2.4.11-1.el6.x86_64.rpm                                                                                                                    | 8.1 MB     00:01     
(3/4): perl-DBD-MySQL-4.013-3.el6.x86_64.rpm                                                                                                                            | 134 kB     00:00     
(4/4): perl-DBI-1.609-4.el6.x86_64.rpm                                                                                                                                  | 705 kB     00:00     
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total                                                                                                                                                          2.5 MB/s |  11 MB     00:04     
warning: rpmts_HdrFromFdno: Header V4 DSA/SHA1 Signature, key ID cd2efd2a: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-Percona
Importing GPG key 0xCD2EFD2A:
 Userid : Percona MySQL Development Team <mysql-dev@percona.com>
 Package: percona-release-0.1-4.noarch (installed)
 From   : /etc/pki/rpm-gpg/RPM-GPG-KEY-Percona
Is this ok [y/N]: y
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Warning: RPMDB altered outside of yum.
** Found 3 pre-existing rpmdb problem(s), 'yum check' output follows:
2:postfix-2.6.6-6.el6_5.x86_64 has missing requires of libmysqlclient.so.16()(64bit)
2:postfix-2.6.6-6.el6_5.x86_64 has missing requires of libmysqlclient.so.16(libmysqlclient_16)(64bit)
2:postfix-2.6.6-6.el6_5.x86_64 has missing requires of mysql-libs
  Installing : perl-DBI-1.609-4.el6.x86_64                                                                                                                                                 1/4 
  Installing : Percona-Server-shared-51-5.1.73-rel14.12.625.rhel6.x86_64                                                                                                                   2/4 
  Installing : perl-DBD-MySQL-4.013-3.el6.x86_64                                                                                                                                           3/4 
  Installing : percona-xtrabackup-24-2.4.11-1.el6.x86_64                                                                                                                                   4/4 
  Verifying  : percona-xtrabackup-24-2.4.11-1.el6.x86_64                                                                                                                                   1/4 
  Verifying  : perl-DBD-MySQL-4.013-3.el6.x86_64                                                                                                                                           2/4 
  Verifying  : Percona-Server-shared-51-5.1.73-rel14.12.625.rhel6.x86_64                                                                                                                   3/4 
  Verifying  : perl-DBI-1.609-4.el6.x86_64                                                                                                                                                 4/4 

Installed:
  percona-xtrabackup-24.x86_64 0:2.4.11-1.el6                                                                                                                                                  

Dependency Installed:
  Percona-Server-shared-51.x86_64 0:5.1.73-rel14.12.625.rhel6                      perl-DBD-MySQL.x86_64 0:4.013-3.el6                      perl-DBI.x86_64 0:1.609-4.el6                     

Complete!

检验是否安装成功

[root@wuxiang11 percona-xtrabackup]# rpm -qa|grep xtrabackup
percona-xtrabackup-24-2.4.11-1.el6.x86_64
[root@wuxiang11 percona-xtrabackup]#

备份思路

Xtrabackup提供了全量备份和增量备份两种方式,全量就不解释了,增量是指其可以只备份指定位置后的新增数据。本文介绍的增量备份方法使用到了LSN(Log Sequence Number),可以从备份成功文件夹的xtrabackup_checkpoints文件中获取,其中to_lsn就是下次增量备份的起始位置。
结合两者,我们可以得到下图的备份思路。
Mysql中-Xtrabackup备份和恢复应用

解释如下:

  1. 由于全量备份和增量备份的命令参数不同,所以首先要判断是否需要全量备份。
  2. 如果是全量备份,那么便执行命令,备份成功后,记录xtrabackup_checkpoints文件中的to_lsn,以便后面进行增量备份
  3. 如果是增量备份,那么首先读取上次备份时记录下的to_lsn,如果读取失败,报错并结束。否则执行相应命令,备份成功后记录to_lsn。

编写一个简单的脚本:db-backup.sh,如下所示:

#!/bin/sh

# xtrabackup的相关配置
INNOBACKUPEX="innobackupex "
MY_CNF="/home/config/mysql/3307.backup.cnf"
MY_USER="xtrabackup"
MY_PASSWORD="xtrabackup"
MY_SOCKET="/home/socket/mysql/3307.sock"

# 远程备份机 文件名配置
REMOTE_HOST="dbbackup"
REMOTE_DIR="/home/backup/mysql/test"
LOCAL_LSN_FILE="~/.to_lsn_important"
DATE_NAME=`date +%Y-%m-%d-%H-%M-%S`
REMOTE_FILE=$DATE_NAME.tar.gz
LOCK_FILE="~/.mysql.backup.lock"
LOCAL_BACKUP_DIR="/home/backup/mysql/test/$DATE_NAME"

# 输出帮助信息
function usage()
{
    echo "Usage:"
    echo "-f db will be backuped fully with this parameter. If not , incrementally. "
}

#防止同时执行两个备份命令,发生冲突
if [ -f $LOCK_FILE ] ;then
    echo 'Mysql backup lockfile is locked!'
    exit 0
fi

full=0

while getopts "fh" arg #选项后面的冒号表示该选项需要参数
do
    case $arg in
        f)  
            full=1
            ;;
        h)  # 输出帮助信息
            usage
            exit 0
            ;;
    esac
done

echo "backup dir is $REMOTE_DIR/$REMOTE_FILE"

# backup up db to remote host
echo "start to backup db!"`date +%Y-%m-%d-%H-%M-%S`
if [ "$full"x = "1"x ] ;then
    # 全量备份
    echo '1' > $LOCK_FILE
    $INNOBACKUPEX --defaults-file=$MY_CNF --user=$MY_USER --password=$MY_PASSWORD --socket=$MY_SOCKET ./ --stream=tar | gzip | ssh $REMOTE_HOST "cat - > $REMOTE_DIR/FULL-$REMOTE_FILE"
    ssh $REMOTE_HOST "cd $REMOTE_DIR;rm -f xtrabackup_checkpoints;tar zxfi $REMOTE_DIR/FULL-$REMOTE_FILE xtrabackup_checkpoints "
    toLSN=$( ssh $REMOTE_HOST "cat $REMOTE_DIR/xtrabackup_checkpoints|grep to_lsn|awk -F= '{gsub(/ /,\"\",\$2);print \$2}'" )
    if [ $toLSN ] ;then
        echo $toLSN > $LOCAL_LSN_FILE
    else
        echo 'no lsn from remote host!please check!'
    fi
else
    # 增量备份
    if [ -f $LOCAL_LSN_FILE ] ;then
        toLSN=`cat $LOCAL_LSN_FILE`
    fi

    if [ ! $toLSN ] ;then
        echo 'last LSN is not set !please check!'
        exit 0
    fi

    echo '1' > $LOCK_FILE
    mkdir -p $LOCAL_BACKUP_DIR
    echo "last to lsn is "$toLSN
    $INNOBACKUPEX --parallel=6 --defaults-file=$MY_CNF --user=$MY_USER --password=$MY_PASSWORD --socket=$MY_SOCKET --incremental --incremental-lsn=$toLSN $LOCAL_BACKUP_DIR 2>/tmp/innobackexLog
    toLSN=$( cd $LOCAL_BACKUP_DIR/*; cat xtrabackup_checkpoints|grep to_lsn|awk -F= '{gsub(/ /,"",$2);print $2}' )
    echo "new to lsn is "$toLSN;
    if [ $toLSN ] ;then
        echo $toLSN > $LOCAL_LSN_FILE
        cd $LOCAL_BACKUP_DIR/*;tar zc .|ssh $REMOTE_HOST "cat - > $REMOTE_DIR/$REMOTE_FILE"
        echo "save file to $REMOTE_HOST @ $REMOTE_DIR/$REMOTE_FILE"
    else
        echo 'no lsn from local backup file!delete remote backup file!'$LOCAL_BACKUP_DIR/$REMOTE_FILE
    fi
    echo "remove $LOCAL_BACKUP_DIR"
    rm -rf $LOCAL_BACKUP_DIR
fi

rm -f $LOCK_FILE
echo "end to backup db!"`date +%Y-%m-%d-%H-%M-%S`

将上述脚本配置好后,放到mysql主机上,执行 sh db-backup.sh -f进行全量备份,之后将sh backup.sh添加到crontab中每小时增量备份一次就可以了。

注意--parallel=6使用是有条件的,参考文档

恢复思路

一旦线上数据库发生宕机之类的灾难性事故,备份数据就要立马发挥作用了。打开备份文件夹一看,如上面的图,每小时一个压缩文件,时间久了,茫茫多,上百个压缩文件,简直是一定的,这必须得来个脚本自动化恢复数据才成。思路很简单,见下图:

Mysql中-Xtrabackup备份和恢复应用

解释如下:

  1. 先解压,没啥说的。
  2. 找到全量备份的数据,因为增量备份也是以此为基准进行的。上面备份的时候,全量备份文件命名以FULL开头便是为了此处便于查找。
  3. 先恢复全量备份数据,然后按照时间顺序恢复增量备份的数据。
  4. 将数据恢复到mysql中
  5. 启动mysql,连上看看有没问题。

简单的实现脚本,我们叫它restore.sh,如下所示

#!/bin/sh
BACK_DIR="/home/backup/mysql/test"
RESTORE_DIR="/home/tmpback/test"

# xtrabackup恢复时使用的配置文件可能与数据库配置文件不同
RESTORE_MY_CNF="/home/config/mysql/3307.backup.cnf"

# 启动mysql需要的配置文件,按需设定
MY_CNF="/home/config/mysql/3307.cnf"
MY_DATA_DIR="/home/data/mysql/3307"
MY_SOCK_DIR="/home/socket/mysql/"
MY_LOG_DIR="/home/logs/mysqld/3307"

#extract all tar file
fullFileName=""
for file in $( ls $BACK_DIR | grep "tar.gz" )
do
    fileName=${file%.tar.gz}
    full=${file%%-*}
    if [ "${full}"x = "FULL"x ] ;then
        fullFileName=$fileName
    fi
    DEST_DIR="$RESTORE_DIR/$fileName"
    if [ -d $DEST_DIR ] ;then
        echo "$DEST_DIR exists!"
    else
        mkdir -p $DEST_DIR
        echo "start to extract file $file to $DEST_DIR"
        tar zxif $BACK_DIR/$file -C $RESTORE_DIR/$fileName
        echo "end to extract file "$file
    fi
done

echo "full backup dir is "$fullFileName

echo "**start to repare full backup dir"

# 恢复全量数据
echo "innobackupex --apply-log --redo-only --use-memory=4G $RESTORE_DIR/$fullFileName"
innobackupex --apply-log --redo-only --use-memory=4G "$RESTORE_DIR/$fullFileName"

echo "**end to repare full backup dir"

# 恢复增量数据
for file in $( ls $RESTORE_DIR|grep -v "FULL" )
do
    echo "**start to repare $file"
    echo "innobackupex --apply-log --redo-only --use-memory=4G $RESTORE_DIR/$fullFileName --incremental-dir=$RESTORE_DIR/$file"
    innobackupex --apply-log --redo-only --use-memory=4G "$RESTORE_DIR/$fullFileName" --incremental-dir="$RESTORE_DIR/$file"

    echo "**end to repare $file"

done

echo "**start to copy back data to mysql"
rm -rf $MY_DATA_DIR
mkdir $MY_DATA_DIR
mkdir $MY_SOCK_DIR
mkdir $MY_LOG_DIR

#将数据恢复到mysql中
echo "innobackupex --defaults-file=$RESTORE_MY_CNF --copy-back $RESTORE_DIR/$fullFileName"
innobackupex --defaults-file=$RESTORE_MY_CNF --copy-back $RESTORE_DIR/$fullFileName
echo "**end to copy back data to mysql"

chown -R mysql:mysql $MY_DATA_DIR
chown -R mysql:mysql $MY_SOCK_DIR
chown -R mysql:mysql $MY_LOG_DIR

echo "All data has been restored! Try to start mysql now"

echo "mysqld_multi --defaults-file=$MY_CNF start 1"

使用方法很简单,配置好后,直接运行sh restore.sh就可以了。