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Linux下的MYSQL主主复制

来源:互联网 作者:佚名 时间:2013-10-17 14:58
为什么,会有mysql的主主复制。因为在一些高可用的环境中,mysql的主从不能满足现实中的一些实际需求。比如,一些流量大的网站数据库访问有了瓶颈,需要负载均衡

为什么,会有mysql的主主复制。因为在一些高可用的环境中,mysql的主从不能满足现实中的一些实际需求。比如,一些流量大的网站数据库访问有了瓶颈,需要负载均衡的时候就用两个或者多个的mysql服务器,而这些mysql服务器的数据库数据必须要保持一致,那么就会用到主主复制。

mysql主从架构中其实就一个主在工作,而从就相当于一个备份机器,从通过日志监测的方式来备份主库上的数据而保证主库的数据安全。在这种架构中如果从上的数据做了改变,主数据是不会用任何变化的。因为mysql主从架构主要是mysql从监控mysql主的日志变化来实现同步,相反的在这个架构中主并没有监控从的日志变化。所以,mysql从数据反生变化,主也就没有什么变化了。

通过上述描述,可以看到如果想实现主主复制,无非就是在mysql主从架构上让mysql主实现监测从的日志变化,从而实现两台机器相互同步。(主从的架构前面有博文)

实验环境:两台服务器:

主机名:HA1,HA2(呵呵,这个主机名是英文缩写High availability,高可用的意思)

ip:192.168.1.231

192.168.1.232

主机系统:centos6.4

mysql版本5.5.22

首先,看下HA1(192.168.1.231)的mysql配置文件

vim /etc/my.cnf # Example MySQL config file for very large systems. # # This is for a large system with memory of 1G-2G where the system runs mainly # MySQL. # # MySQL programs look for option files in a set of # locations which depend on the deployment platform. # You can copy this option file to one of those # locations. For information about these locations, see: # # # In this file, you can use all long options that a program supports. # If you want to know which options a program supports, run the program # with the "--help" option. # The following options will be passed to all MySQL clients [client] #password = your_password port = 3306 socket = /usr/local/mysql/tmp/mysql.sock # Here follows entries for some specific programs # The MySQL server [mysqld] port = 3306 socket = /usr/local/mysql/tmp/mysql.sock skip-external-locking key_buffer_size = 384M max_allowed_packet = 1M table_open_cache = 512 sort_buffer_size = 2M read_buffer_size = 2M read_rnd_buffer_size = 8M myisam_sort_buffer_size = 64M thread_cache_size = 8 query_cache_size = 32M # Try number of CPU's*2 for thread_concurrency thread_concurrency = 8 # Don't listen on a TCP/IP port at all. This can be a security enhancement, # if all processes that need to connect to mysqld run on the same host. # All interaction with mysqld must be made via Unix sockets or named pipes. # Note that using this option without enabling named pipes on Windows # (via the "enable-named-pipe" option) will render mysqld useless! # #skip-networking # Replication Master Server (default) # binary logging is required for replication log-bin=mysql-bin log-slave-updates # required unique id between 1 and 2^32 - 1 # defaults to 1 if master-host is not set # but will not function as a master if omitted server-id = 1

在这个配置文件中,需要特别注意的三处地方:

log-bin=mysql-bin:这个选项基本默认都是开着的,如果没有打开,可以手动打开。

log-slave-updates:这个选项特别的重要它是为了让slave也能充当master,同时也为了更好的服务于 m-m + s 的环境,保证slave挂在任何一台master上都会接收到另一个master的写入信息。当然不局限于这个架构,级联复制的架构同样也需要log-slave-updates的支持。

server-id = 1:这个ID为服务器ID如果配置一样会出现冲突,而不能复制

接着再看下HA2(192.168.1.232)的mysql配置文件

vim /etc/my.cnf # Example MySQL config file for very large systems. # # This is for a large system with memory of 1G-2G where the system runs mainly # MySQL. # # MySQL programs look for option files in a set of # locations which depend on the deployment platform. # You can copy this option file to one of those # locations. For information about these locations, see: # # # In this file, you can use all long options that a program supports. # If you want to know which options a program supports, run the program # with the "--help" option. # The following options will be passed to all MySQL clients [client] #password = your_password port = 3306 socket = /usr/local/mysql/tmp/mysql.sock # Here follows entries for some specific programs # The MySQL server [mysqld] port = 3306 socket = /usr/local/mysql/tmp/mysql.sock skip-external-locking key_buffer_size = 384M max_allowed_packet = 1M table_open_cache = 512 sort_buffer_size = 2M read_buffer_size = 2M read_rnd_buffer_size = 8M myisam_sort_buffer_size = 64M thread_cache_size = 8 query_cache_size = 32M # Try number of CPU's*2 for thread_concurrency thread_concurrency = 8 # Don't listen on a TCP/IP port at all. This can be a security enhancement, # if all processes that need to connect to mysqld run on the same host. # All interaction with mysqld must be made via Unix sockets or named pipes. # Note that using this option without enabling named pipes on Windows # (via the "enable-named-pipe" option) will render mysqld useless! # #skip-networking # Replication Master Server (default) # binary logging is required for replication log-bin=mysql-bin log-slave-updates # required unique id between 1 and 2^32 - 1 # defaults to 1 if master-host is not set # but will not function as a master if omitted server-id = 10 # Replication Slave (comment out master section to use this)

在HA2的mysql配置文件中,除了server-id不一样,其他几乎一模一样。配置文件写好后,我们把两台服务器上的mysql服务器启动起来。

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