目录

文/温国兵

一 为什么需要延时备份

在上一篇文章中,我们讲到MySQL备份与恢复之percona-xtrabackup实现增量备份及恢复,percona-xtrabackup是一个优秀的用于增量备份的工具。今天我们讲到的延时备份也是使用他们的产品。

以前在MySQL AB复制一文中提到了AB复制。我们首先回顾下MySQL复制的相关要点。AB复制又称主从复制,实现的是数据同步。经过以下步骤:

1)主服务器把数据更改记录到二进制日志中,这个操作叫做二进制日志事件;
2)从服务器把主服务器的二进制日志事件拷贝到自己的中继日志(relay log)中;
3)从服务器执行中继日志中的事件,把更改应用到自己的数据上。

在生产中,我们在使用 mysql AB 复制技术不但可以起到数据库层面负载均衡的能力,还可以起到备份数据的功能,但有的时候我们可能由于不小心误操作导致数据被删除,这这个时候 slave服务器上的数据也会同时被删除,如果我们能够能是的其中的一台 slave 延时备份的话, 这样就可以从 slave服务器上找回被误删的数据了。

从服务器到主服务器中拷贝二进制日志文件,如果在并发量高,网络延时严重的情况下,会对主服务器造成相当大的压力,负载高,必定会出现很多问题,比如访问延迟,IO瓶颈,网络拥塞等等。服务器压力过大是我们都不愿看到的情况,那有没有方案缓解这种情况呢?有,这就是本文讲到的延时备份。延时备份通过第三方工具,将检查同步和真正同步的时间控制在一定的范围内,而不是主服务器数据发生变化,从服务器立即去同步二进制事件到自己的中继日志中,这样的话可以大大减轻主服务器的压力,并且基于AB复制的优点,可以达到备份数据的目的。

好了,看下延时备份的示意图。

二 延时备份示意图

MySQL备份与恢复之MySQL
MySQL备份与恢复之MySQL 延时备份示意图

三 延时备份模拟

网络拓扑图

MySQL备份与恢复之MySQL
MySQL备份与恢复之MySQL 延时备份网络拓扑图

实验环境简介。

主机 IP地址 主机名 备注
serv01 192.168.1.11 serv01.host.com 主服务器
serv08 192.168.1.18 serv08.host.com 及时同步服务器
serv09 192.168.1.19 serv09.host.com 延时同步服务器

操作系统版本
RHEL Server6.1 64位系统

使用到的软件包版本

  • mysql-5.5.29-linux2.6-x86_64.tar.gz
  • percona-toolkit-2.1.7-1.noarch.rpm

第一步,搭建环境。修改配置文件,注意每台的server-id不一致。

# serv01
cat /etc/my.cnf | grep server-id
server-id = 1
#server-id = 2
/etc/init.d/mysqld start
Starting MySQL SUCCESS!

# serv08
cat /etc/my.cnf | grep server-id
server-id = 2
#server-id = 2
/etc/init.d/mysqld start
Starting MySQL SUCCESS!

# serv09
cat /etc/my.cnf | grep server-id
server-id = 3
#server-id = 2
/etc/init.d/mysqld start
Starting MySQL SUCCESS!

第二步,serv01、serv08、serv09清空日志。

--serv01
mysql> show binary logs;
+------------------+-----------+
| Log_name | File_size |
+------------------+-----------+
| mysql-bin.000001 | 683 |
+------------------+-----------+
1 row in set (0.01 sec)

mysql> reset master;
Query OK, 0 rows affected (0.01 sec)

mysql> show binary logs;
+------------------+-----------+
| Log_name | File_size |
+------------------+-----------+
| mysql-bin.000001 | 107 |
+------------------+-----------+
1 row in set (0.00 sec)

--serv08
mysql> reset master;
Query OK, 0 rows affected (0.02 sec)

mysql> show binary logs;
+------------------+-----------+
| Log_name | File_size |
+------------------+-----------+
| mysql-bin.000001 | 107 |
+------------------+-----------+
1 row in set (0.00 sec)

--serv09
mysql> show binary logs;
+------------------+-----------+
| Log_name | File_size |
+------------------+-----------+
| mysql-bin.000001 | 107 |
+------------------+-----------+
1 row in set (0.00 sec)

mysql> reset master;
Query OK, 0 rows affected (0.00 sec)

mysql> show binary logs;
+------------------+-----------+
| Log_name | File_size |
+------------------+-----------+
| mysql-bin.000001 | 107 |
+------------------+-----------+
1 row in set (0.00 sec)

第三步,主服务器serv01创建授权用户。

mysql> grant replication client, \
replication slave on *.* to 'larry'@'192.168.1.%' \
identified by 'larry';

第四步,serv08修改master设置,开启slave,查看slave状态。

mysql> change master to
    -> master_host='192.168.1.11',
    -> master_user='larry',
    -> master_password='larry',
    -> master_port=3306,
    -> master_log_file='mysql-bin.000001',
    -> master_log_pos=107;
Query OK, 0 rows affected (0.03 sec)

mysql> start slave;
Query OK, 0 rows affected (0.00 sec)

mysql> show slave status \G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.1.11
                  Master_User: larry
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000001
          Read_Master_Log_Pos: 107
               Relay_Log_File: serv08-relay-bin.000002
                Relay_Log_Pos: 253
        Relay_Master_Log_File: mysql-bin.000001
             **Slave_IO_Running: Yes**
            **Slave_SQL_Running: Yes**
              Replicate_Do_DB:
          Replicate_Ignore_DB:
           Replicate_Do_Table:
       Replicate_Ignore_Table:
      Replicate_Wild_Do_Table:
  Replicate_Wild_Ignore_Table:
                   Last_Errno: 0
                   Last_Error:
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 107
              Relay_Log_Space: 410
              Until_Condition: None
               Until_Log_File:
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File:
           Master_SSL_CA_Path:
              Master_SSL_Cert:
            Master_SSL_Cipher:
               Master_SSL_Key:
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error:
               Last_SQL_Errno: 0
               Last_SQL_Error:
  Replicate_Ignore_Server_Ids:
             Master_Server_Id: 1
1 row in set (0.00 sec)

ERROR:
No query specified

第五步,serv09延时服务器修改master状态,开启slave,查看slave状态。

mysql> change master to \
master_host='192.168.1.11', \
master_user='larry', \
master_password='larry', \
master_port=3306, \
master_log_file='mysql-bin.000001', \
master_log_pos=107;
Query OK, 0 rows affected (0.02 sec)

mysql> start slave;
Query OK, 0 rows affected (0.01 sec)

mysql> show slave status \G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.1.11
                  Master_User: larry
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000001
          Read_Master_Log_Pos: 107
               Relay_Log_File: serv09-relay-bin.000002
                Relay_Log_Pos: 253
        Relay_Master_Log_File: mysql-bin.000001
             **Slave_IO_Running: Yes**
            **Slave_SQL_Running: Yes**
              Replicate_Do_DB:
          Replicate_Ignore_DB:
           Replicate_Do_Table:
       Replicate_Ignore_Table:
      Replicate_Wild_Do_Table:
  Replicate_Wild_Ignore_Table:
                   Last_Errno: 0
                   Last_Error:
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 107
              Relay_Log_Space: 410
              Until_Condition: None
               Until_Log_File:
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File:
           Master_SSL_CA_Path:
              Master_SSL_Cert:
            Master_SSL_Cipher:
               Master_SSL_Key:
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error:
               Last_SQL_Errno: 0
               Last_SQL_Error:
  Replicate_Ignore_Server_Ids:
             Master_Server_Id: 1
1 row in set (0.00 sec)

ERROR:
No query specified

第六步,在没有使用延时服务器时,serv01创建测试数据库,可以看到同步服务器serv08和延时服务器serv09已经同步了。

--serv01
mysql> create database justdb;
Query OK, 1 row affected (0.01 sec)

mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| crm |
| justdb |
| larry |
| larrydb |
| mysql |
| performance_schema |
| test |
+--------------------+
8 rows in set (0.00 sec)

--serv08
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| justdb |
| larrydb |
| mysql |
| performance_schema |
| test |
+--------------------+
6 rows in set (0.03 sec)

--serv09
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| justdb |
| larry |
| larrydb |
| mysql |
| performance_schema |
| test |
+--------------------+
7 rows in set (0.00 sec)

第七步,拷贝percona-toolkit-2.1.7-1.noarch.rpm。

scp percona-toolkit-2.1.7-1.noarch.rpm 192.168.1.11:/opt

第八步,主服务器中通过yum安装percona-toolkit-2.1.7-1.noarch.rpm。

yum install percona-toolkit-2.1.7-1.noarch.rpm -y

第九步,使用pt-slave-delay工具进行延时设置。可以先查看帮助。

pt-slave-delay --help

第十步,serv09延时服务器中创建授权用户

mysql> grant all on *.* to 'rep'@'192.168.1.%' identified by 'larry';
Query OK, 0 rows affected (0.00 sec)

第十一步,实现功能。

pt-slave-delay --user='rep' \
--password='larry' \
--delay=3m \
--interval=20s \
--run-time=30m \
192.168.1.19
2013-10-06T19:43:30 slave running 0 seconds behind
2013-10-06T19:43:30 STOP SLAVE until 2013-10-06T19:46:30
at master position mysql-bin.000001/199

命令解释

–user=’rep’:延时服务器中授权用户的用户名,这里设置为rep
–password=’larry’:延时服务器中授权用户的密码,这里设置为larry
–delay=3m:延时同步的时间,这里设置为3分钟
–interval=20s:检查同步的时间,这里设置为20s
–run-time=30m:pt-slave-delay的运行时间,这里设置为30分钟
192.168.1.19:延时服务器的IP地址

第十二步,测试,主服务器serv01创建测试数据库,可以发现同步服务器立马更新,而延时同步服务器要等3分钟之后才更新。

--serv01
mysql> use justdb;
Database changed
mysql> create table test(id int);
Query OK, 0 rows affected (0.01 sec)

mysql> insert into test values(1);
Query OK, 1 row affected (0.00 sec)

--serv08
  mysql> select * from justdb.test;
+------+
| id |
+------+
| 1 |
+------+
1 row in set (0.00 sec)

--serv09
mysql> select * from justdb.test;
ERROR 1146 (42S02): Table 'justdb.test' doesn't exist

三分钟过后查看延时服务器已经同步成功。

pt-slave-delay --user='rep' \
--password='larry' \
--delay=3m \
--interval=20s \
--run-time=30m \
192.168.1.19

2013-10-06T19:43:30 slave running 0 seconds behind
2013-10-06T19:43:30 STOP SLAVE until 2013-10-06T19:46:30
at master position mysql-bin.000001/199
2013-10-06T19:43:50 slave stopped at master position mysql-bin.000001/199
2013-10-06T19:44:10 slave stopped at master position mysql-bin.000001/199
2013-10-06T19:44:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:44:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:45:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:45:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:45:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:46:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:46:30 no new binlog events
2013-10-06T19:46:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:47:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:47:30 START SLAVE until master 2013-10-06T19:44:30 mysql-bin.000001/492
**2013-10-06T19:47:50 slave running 0 seconds behind**
**2013-10-06T19:47:50 STOP SLAVE until 2013-10-06T19:50:50
at master position mysql-bin.000001/492**
2013-10-06T19:48:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:48:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:48:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:49:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:49:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:49:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:50:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:50:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:50:50 no new binlog events
2013-10-06T19:51:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:51:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:51:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:52:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:52:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:52:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:53:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:53:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:53:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:54:10 no new binlog events
2013-10-06T19:54:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:54:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:55:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:55:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:55:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:56:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:56:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:56:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:57:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:57:30 no new binlog events
2013-10-06T19:57:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:58:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:58:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:58:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:59:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:59:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T19:59:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:00:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:00:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:00:50 no new binlog events
2013-10-06T20:01:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:01:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:01:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:02:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:02:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:02:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:03:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:03:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:03:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:04:10 no new binlog events
2013-10-06T20:04:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:04:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:05:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:05:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:05:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:06:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:06:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:06:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:07:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:07:30 no new binlog events
2013-10-06T20:07:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:08:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:08:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:08:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:09:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:09:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:09:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:10:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:10:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:10:50 no new binlog events
2013-10-06T20:11:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:11:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:11:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:12:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:12:30 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:12:50 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:13:10 slave stopped at master position mysql-bin.000001/492
2013-10-06T20:13:30 slave stopped at master position mysql-bin.000001/492
**2013-10-06T20:13:30 Setting slave to run normally**

延时服务器登录查看。

mysql> select * from justdb.test;
+------+
| id |
+------+
| 1 |
+------+
1 row in set (0.00 sec)

四 附延时备份脚本

#!/bin/bash
#
# chkconfig: - 88 12
# description: the mysql ab delay scripts

host=192.168.100.54
user=rep
password=larry

delay=2m
in=15s

prog=/usr/bin/pt-slave-delay

. /etc/init.d/functions

start() {
    echo -n "Starting `basename $prog`..."
    daemon $prog --host=$host --user=$user \
    --password=$password \
    --delay=$delay \
    --interval=$in \
    --daemonize \
    --log=/var/log/mysql-delay.log
    echo
}

stop() {
    echo -n "Stopping `basename $prog`..."
    killproc $prog
    echo
}

case "$1" in
    start)
        start
        ;;
    stop)
        stop
        ;;
    restart)
        stop
        start
        ;;
    *)
        echo "Usage: $0 {start|stop|restart}"
        exit 1
esac

五 资源下载

percona-toolkit-2.1.7-1.noarch.rpm:percona-toolkit-2.1.7-1.noarch.rpm

–EOF–

原文地址:MySQL备份与恢复之MySQL

题图来自:原创,By Robin Wen

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