linux系统下实现mysql热备份详细步骤(mysql主从复制)

主从的作用：

1.可以当做一种备份方式

2.用来实现读写分离，缓解一个数据库的压力

 mysql主从备份原理：

mysql的主从复制至少是需要两个mysql的服务，当然mysql的服务是可以分布在不同的服务器上，也可以在一台服务器上启动多个服务。

如果想配置成为同一台上的话，注意安装的时候，选择两个不同的prefix=路径，同时开启服务器的时候，端口不能相同。

(1)首先确保主从服务器上的mysql版本相同（做主从服务器的原则是，mysql版本要相同，如果不能满足，最起码从服务器的mysql的版本必须高于主服务器的mysql版本 ）

(2)在主服务器上,设置一个从数据库的账户,使用replication slave赋予权限,如:

 mysql> grant replication slave on *.* to 'slave001'@'192.168.0.99' identified by

'123456';

query ok, 0 rows affected (0.13 sec)

[原理]master 上提供binlog ,

slave 通过 i/o线程从 master拿取 binlog,并复制到slave的中继日志中

slave 通过 sql线程从 slave的中继日志中读取binlog ,然后解析到slave中

 主从复制大前提

需要master与slave同步，因为笔者的数据库数据量不大，所以无需考虑太多，直接把

master上的data复制到了slave上，但是如果是大的数据量，比如像taobao这个的系统

实验环境准备：

os： centos5.4

mysql:mysql-5.0.41.tar.gz
辅助工具:ssh secure shell client

两台测试ip&服务器：

master server: 192.168.1.2/linux centos5.4/mysql 5.0
slave server: 192.168.1.3/linux centos5.4/mysql 5.0

 安装配置步骤：

 1、首先在linux环境下分配好磁盘分区以便留足mysql数据库的备份空间

[root@vps mysql]# df -h
filesystem size used avail use% mounted on
/dev/simfs 30g 2.0g 29g 7% /

 2、mysql数据库的安装：

1>将mysql-5.0.41.tar.gz通过ssh 工具 上传到linux系统的home目录下

2>建立mysql使用者和群组:

#groupadd mysql
#useradd -g mysql mysql

3>解压缩mysql-5.0.41.tar.gz源码包

#cd /usr/local/sofrware
#tar zxvf mysql-5.0.41.tar.gz

4>进入源码目录编译安装

#cd /home/mysql-5.0.41
#./configure --prefix=/usr/local/mysql --with-charset=gbk |注:配置mysql安装路径并且支持中文
#make |注:编译
#make install |注:编译安装

5>替换/etc/my.cnf文件,进入源码包,执行命令

#cd /home/mysql-5.0.41
#cp support-files/my-medium.cnf /etc/my.cnf

6>完成以上操作以后进行初始化数据库,进入已经安装好的mysql目录

#cd /usr/local/mysql
#bin/mysql_install_db --user=mysql |注:--user=mysql 初始化表并且规定用mysql用户

7>设置给mysql和root用户设定访问权限 我们先进入mysql目录

#cd /usr/local/mysql
#chown -r root /usr/local/mysql 　　　　　注:设定root能访问/usr/local/mysq
#chown -r mysql /usr/local/mysql/var 　　注:设定mysql用户能访问/usr/local/mysql/var
#chgrp -r mysql /usr/local/mysql 　　　　注:设定mysql组能够访问/usr/local/mysq

8>启动mysql,进入已经安装好的目录

#cd /usr/local/mysql
#bin/mysqld_safe --user=mysql &

9>
修改mysql数据库超级用户root的缺省密码:

/usr/local/mysql/bin/mysqladmin -u root password 'mysql'

关闭mysql服务器

cd /usr/local/mysql/bin
./mysqladmin -u root -p shutdown

10>设定开机就启动mysql,进入源码目录下

# cd /home/mysql-5.0.41
# cp support-files/mysql.server /etc/init.d/mysql

# chmod +x /etc/init.d/mysql
# chkconfig --level 345 mysql on
# service mysql restart
shutting down mysql. [ 确定 ]
starting mysql [ 确定 ]
[root@localhost mysql]#

到这里mysql就装好了。
 

3、配置mysql5.0的复制（replication）功能

 一.将master设置为只读。

mysql> flush tables with read lock;

二.用master中的data文件夹替换slave中的data文件夹

比如 用 tar zcvf mysql_data.gz /media/raid10/mysql/3306/data

然后 mv mysql_data.gz /media/raid10/htdocs/blog/wordpress/

因为我的 /media/raid10/htdocs/blog/wordpress/ 是 nginx 的主目录

所以可以在 slave上，用wget下载这个文件，然后 解压，并覆盖slave上的data文件

注意：覆盖之前最好备份源文件

三.配置master的my.cnf,添加以下内容

在[mysqld]配置段添加如下字段

server-id=1

log-bin=/media/raid10/mysql/3306/binlog/binlog //这里写你的binlog绝对路径名

binlog-do-db=blog //需要同步的数据库，如果没有本行，即表示同步所有的数据库

binlog-ignore-db=mysql //被忽略的数据库

 

这里给出我的my.cnf配置文件

[client]

character-set-server = utf8

port = 3306

socket = /tmp/mysql.sock

[mysqld]

character-set-server = utf8

replicate-ignore-db = mysql

replicate-ignore-db = test

replicate-ignore-db = information_schema

user = mysql

port = 3306

socket = /tmp/mysql.sock

basedir = /usr/local/webserver/mysql

datadir = /media/raid10/mysql/3306/data

log-error = /media/raid10/mysql/3306/mysql_error.log

pid-file = /media/raid10/mysql/3306/mysql.pid

open_files_limit = 10240

back_log = 600

max_connections = 5000

max_connect_errors = 6000

table_cache = 614

external-locking = false

max_allowed_packet = 16m

sort_buffer_size = 1m

join_buffer_size = 1m

thread_cache_size = 300

#thread_concurrency = 8

query_cache_size = 20m

query_cache_limit = 2m

query_cache_min_res_unit = 2k

default-storage-engine = myisam

thread_stack = 192k

transaction_isolation = read-committed

tmp_table_size = 20m

max_heap_table_size = 20m

long_query_time = 3

log-slave-updates

log-bin = /media/raid10/mysql/3306/binlog/binlog

binlog-do-db=blog

binlog-ignore-db=mysql

 binlog_cache_size = 4m

binlog_format = mixed

max_binlog_cache_size = 8m

max_binlog_size = 20m

relay-log-index = /media/raid10/mysql/3306/relaylog/relaylog

relay-log-info-file = /media/raid10/mysql/3306/relaylog/relaylog

relay-log = /media/raid10/mysql/3306/relaylog/relaylog

expire_logs_days = 30

key_buffer_size = 10m

read_buffer_size = 1m

read_rnd_buffer_size = 6m

bulk_insert_buffer_size = 4m

myisam_sort_buffer_size = 8m

myisam_max_sort_file_size = 20m

myisam_repair_threads = 1

myisam_recover

 interactive_timeout = 120

wait_timeout = 120

 skip-name-resolve

#master-connect-retry = 10

slave-skip-errors = 1032,1062,126,1114,1146,1048,1396

#master-host = 192.168.1.2

#master-user = username

#master-password = password

#master-port = 3306

 server-id = 1

innodb_additional_mem_pool_size = 16m

innodb_buffer_pool_size = 20m

innodb_data_file_path = ibdata1:56m:autoextend

innodb_file_io_threads = 4

innodb_thread_concurrency = 8

innodb_flush_log_at_trx_commit = 2

innodb_log_buffer_size = 16m

innodb_log_file_size = 20m

innodb_log_files_in_group = 3

innodb_max_dirty_pages_pct = 90

innodb_lock_wait_timeout = 120

innodb_file_per_table = 0

 #log-slow-queries = /media/raid10/mysql/3306/slow.log

#long_query_time = 10

 [mysqldump]

quick

max_allowed_packet = 32m

 

四.在master机上为slave机添加一同步帐号

mysql> grant replication slave on *.* to 'admin'@'172.29.141.115' identified by '12345678';

mysql> flush privileges ;

 

五.配置slave的my.cnf,添加以下内容

注意:

1.如果mysql是5.5.3-m3 的版本，只需

在[mysqld]字段下添加如下内容

server-id=2

 2.如果是5.0x的版本，需要

在[mysqld]字段下添加如下内容

server-id=2

log-bin=mysql-bin //这是同步的binlog，具体以你的binlog为准

master-host=172.29.141.112

master-user=admin

master-password=12345678

master-port=3306

master-connect-retry=60 //如果发现主服务器断线，重新连接的时间差；

replicate-do-db=blog //同步的数据库，不写本行 表示 同步所有数据库

replicate-ignore-db=mysql //不需要备份的数据库

log-slave-update

slave-skip-errors

 我的mysql是5.5.3，这里给出我的slave my.cnf配置文件

[client]

character-set-server = utf8

port = 3306

socket = /tmp/mysql.sock

 

[mysqld]

character-set-server = utf8

replicate-ignore-db = mysql

replicate-ignore-db = test

replicate-do-db = blog

replicate-ignore-db = information_schema

user = mysql

port = 3306

socket = /tmp/mysql.sock

basedir = /usr/local/webserver/mysql

datadir = /media/raid10/mysql/3306/data

log-error = /media/raid10/mysql/3306/mysql_error.log

pid-file = /media/raid10/mysql/3306/mysql.pid

open_files_limit = 10240

back_log = 600

max_connections = 5000

max_connect_errors = 6000

table_cache = 614

external-locking = false

max_allowed_packet = 16m

sort_buffer_size = 1m

join_buffer_size = 1m

thread_cache_size = 300

#thread_concurrency = 8

query_cache_size = 20m

query_cache_limit = 2m

query_cache_min_res_unit = 2k

default-storage-engine = myisam

thread_stack = 192k

transaction_isolation = read-committed

tmp_table_size = 20m

max_heap_table_size = 20m

long_query_time = 3

log-slave-updates

log-bin = /media/raid10/mysql/3306/binlog/binlog

binlog_cache_size = 4m

binlog_format = mixed

max_binlog_cache_size = 8m

max_binlog_size = 20m

relay-log-index = /media/raid10/mysql/3306/relaylog/relaylog

relay-log-info-file = /media/raid10/mysql/3306/relaylog/relaylog

relay-log = /media/raid10/mysql/3306/relaylog/relaylog

expire_logs_days = 30

key_buffer_size = 10m

read_buffer_size = 1m

read_rnd_buffer_size = 6m

bulk_insert_buffer_size = 4m

myisam_sort_buffer_size = 8m

myisam_max_sort_file_size = 20m

myisam_repair_threads = 1

myisam_recover

interactive_timeout = 120

wait_timeout = 120

 skip-name-resolve

#master-connect-retry = 60

slave-skip-errors = 1032,1062,126,1114,1146,1048,1396

 #master-host=172.29.141.112

#master-user = admin

#master-password = 12345678

#master-port = 3306

server-id = 2

innodb_additional_mem_pool_size = 16m

innodb_buffer_pool_size = 20m

innodb_data_file_path = ibdata1:56m:autoextend

innodb_file_io_threads = 4

innodb_thread_concurrency = 8

innodb_flush_log_at_trx_commit = 2

innodb_log_buffer_size = 16m

innodb_log_file_size = 20m

innodb_log_files_in_group = 3

innodb_max_dirty_pages_pct = 90

innodb_lock_wait_timeout = 120

innodb_file_per_table = 0

#log-slow-queries = /media/raid10/mysql/3306/slow.log

#long_query_time = 10

[mysqldump]

quick

max_allowed_packet = 32m

 六.通过查看master的状态(在master上查看)，为配置slave做准备

mysql> show master status/g;

error 2006 (hy000): mysql server has gone away

no connection. trying to reconnect...

connection id: 13

current database: blog

*************************** 1. row ***************************

file: binlog.000005

position: 592

binlog_do_db: blog

binlog_ignore_db: mysql

1 row in set (0.01 sec)

error:

no query specified

 从上面的信息，可以看出，master现在使用的binlog是binlog.000005，position是592,那么下面的slave配置必须与这个对应。

 其实binlog.000005是当前master使用的binlog日志文件

position是当前master使用的binlog.000005日志文件的位置

简单理解为master正在使用哪个binlog的哪个数据行(位置)。

七.如果是5.5.3-m3版本mysql,需要启动slave后，配置与master相关对应的信息(在slave上配置)

注意，这个与第六步相对应

mysql> stop slave ;

mysql> change master to master_host='172.29.141.112', master_user='admin', master_password='12345678', master_log_file='binlog.000005', master_log_pos=488;
mysql> change master to master_connect_retry=60;

 这个与5.0的配置my.cnf作用是一样的，配置成与master相对应的内容

主要是配置slave，让slave知道从master的哪个binlog上的哪个位置复制数据。所以需要知道master的ip,user_name,user_passwd,binlog,binlog_position以及多长时间连接一次master

 八.开启slave

mysql> start slave;

 九.解除master只读限制,并做测试

mysql> unlock tables;

mysql> use blog;

mysql> create longxibendi ( a int, b int );

十.从slave上查看

mysql> use blog;

mysql> show tables;

+-----------------------+

| tables_in_blog |

+-----------------------+

| longxibendi |

| wp_commentmeta |

| wp_comments |

| wp_links |

| wp_options |

| wp_postmeta |

| wp_posts |

| wp_term_relationships |

| wp_term_taxonomy |

| wp_terms |

| wp_usermeta |

| wp_users |

+-----------------------+

12 rows in set (0.00 sec)

可以看到成功了！！

 十一.配置过程中，可以用 show slave status/g; 在 slave上

查看 slave的复制情况

十二.如果出现什么问题，可能是防火墙的问题

/etc/init.d/iptables stop 关闭 master 上的防火墙，或者进行相应的配置

常遇到的错误与解决：

1.[mysql]error 2002 (hy000): can't connect to local mysql server through socket '/var/lib/mysql/mysql.sock' (2)

这个错误，网上有很多说法，其实直接的原因是mysql服务器没有启动

之前我按照5.0x配置master-slave，然后启动slave，在连接slave,就会报这个错误

后来发现原因是，mysql slave没有启动起来，然后去查错误日志，发现以下的字段

110505 01:55:20 mysqld_safe mysqld from pid file /media/raid10/mysql/3306/mysql.pid ended

110505 02:04:41 mysqld_safe starting mysqld daemon with databases from /media/raid10/mysql/3306/data

innodb: the innodb memory heap is disabled

innodb: mutexes and rw_locks use innodb's own implementation

110505 2:04:41 innodb: highest supported file format is barracuda.

110505 2:04:41 innodb plugin 1.0.6 started; log sequence number 44338

110505 2:04:41 [error] /usr/local/webserver/mysql/libexec/mysqld: unknown variable 'master-connect-retry=60'

110505 2:04:41 [error] aborting

110505 2:04:41 innodb: starting shutdown...

110505 2:04:43 innodb: shutdown completed; log sequence number 44348

110505 2:04:43 [note] /usr/local/webserver/mysql/libexec/mysqld: shutdown complete

 110505 02:04:43 mysqld_safe mysqld from pid file /media/raid10/mysql/3306/mysql.pid ended

110505 02:07:44 mysqld_safe starting mysqld daemon with databases from /media/raid10/mysql/3306/data

innodb: the innodb memory heap is disabled

innodb: mutexes and rw_locks use innodb's own implementation

110505 2:07:44 innodb: highest supported file format is barracuda.

110505 2:07:45 innodb plugin 1.0.6 started; log sequence number 44348

110505 2:07:45 [error] /usr/local/webserver/mysql/libexec/mysqld: unknown variable 'master-host=172.29.141.112'

110505 2:07:45 [error] aborting

从上面的error，知道 master-connect-retry=60这个my.cnf中的参数有问题，后来从网上搜资料，发现，mysql5.5.3-m3版本不支持这个参数，

然后我把这个参数注释掉，又发现不支持这个参数master-host，从上面的error字段可以看出来。后来，就知道，5.5.3-m3不能按5.0.x那样配置

原来不需要从my.cnf中配置master相关信息，当然server-id是必须的。其他信息，通过 在命令行中 ，登陆 mysql服务器配置。

其实server-id的作用是

第一，标识，区分不同的slave,第二，防止环备份的发生

 

2.last_error: last_sql_error：等错误

这个是从 slave上，运行 show slave status/g; 得到的。出现这个问题，最根本的原因是，slave 没有与当前的master的binlog 和binlog的position对应上

也就是说，slave传输的master binlog 不与当前master正使用的binlog以及binlog的行数对应。

 

3.[error] slave i/o: error connecting to master 'admin@172.29.141.112:3306' - retry-time: 60 retries: 86400, error_code: 2003

这个就是因为防火墙的问题，所以用 /etc/init.d/iptables stop 关闭防火墙就ok了。

 

4.遇到error 2013 (hy000): lost connection to mysql server during query错误。
在/ect/my.cnf的[mysqld]中添加skip-name-resolve