Linux下的MySQL主主复制

文章由LinuxBoy分享于2019-03-30 04:03:24热评（126）

Linux下的MySQL主主复制

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:
# http://dev.mysql.com/doc/mysql/en/option-files.html
#
# 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:
# http://dev.mysql.com/doc/mysql/en/option-files.html
#
# 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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Linux下的MySQL主主复制