mysql主从配置
1、配置主库（master）
1.编辑mysql master的配置文件（/etc/mysql/my.cnf）：
a)将[mysqld]配置节中的server-id置为1
b)同时打开log_bin（即将log_bin前边的#去掉，确保此文件可写）
c)改侦听地址bind-address = 本机IP
d)如果配置文件做了修改，需重启数据库
e)若是首次安装配置主库，需建立授权账号并执行：flush privileges;
2.查看master的日志文件（File）和偏移量（Position）：
a)进入到mysql控制台：mysql �Curoot
b)执行命令：show master status;
c)将file和Position的值记录下来，后面进行从服务器操作的时候需要使用
2、配置从库（slave）
1.安装从库，编辑mysql slave的配置文件：
a)将[mysqld]配置节中的server-id置为2
b)同时打开log_bin（即将log_bin前边的#去掉，确保此文件可写）
c)改侦听地址bind-address = 本机IP
2.重启数据库，建立和master一样（包括密码）的授权账号，并执行：>flush privileges;
3、导出主库数据
1.如果数据库中的表很多都是innodb引擎，所以不能直接拷贝主数据库的文件，这里需要在从库所在服务器上，将数据导出（这里我们将数据导入到masterdata.sql）：
mysqldump -h <master_ip> -u <username> -p <passwd> --master-data=1 --opt -R --databases <mysql> <db_1> <db_2> <db_3> <db_4> ...... > masterdata.sql
注：--databases 也即-B
2.将master数据导入从库：mysql -uroot < masterdata.sql &
4、配置主从连接信息
在从库的mysql控制台下执行：
mysql> change master to//开始更改从库的master参数
-> master_host='<master_ip>',//从库的master的ip
-> master_user='<username>',//用户名为授权账户，主从必相同
-> master_password='<passwd>',//主从密码一定要相同且正确
-> master_port='3306',//端口一定是3306
-> master_log_file='<mysql-bin.000022>',//此值为master的file值
-> master_log_pos=<2919783>;//此值为master的Position值
命令如下：
change master to master_host='<master_ip>',master_user='<username>',master_password='<passwd>',master_port='3306',master_log_file='<mysql-bin.000022>',master_log_pos=<2919783>;
5、启动从库
1.启动从库：>start slave;
2.再查看主从库是否同步：show slave status\G;
3.必须保证Slave_IO_Running和Slave_SQL_Running这两个值都为yes，否则逐一排查。
4.在进行mysql主从同步时，建议把业务暂停。
6.附：配置文件
#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
#
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html
# This will be passed to all mysql clients
# It has been reported that passwords should be enclosed with ticks/quotes
# escpecially if they contain "#" chars...
# Remember to edit /etc/mysql/debian.cnf when changing the socket location.
[client]
port= 3306
socket= /var/run/mysqld/mysqld.sock
# Here is entries for some specific programs
# The following values assume you have at least 32M ram
# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket= /var/run/mysqld/mysqld.sock
nice= 0
[mysqld]
#
# * Basic Settings
skip-name-resolve
innodb_buffer_pool_size = 2048M
这个参数主要作用是缓存innodb表的索引，数据，插入数据时的缓冲
默认值：128M
专用mysql服务器设置的大小： 操作系统内存的70%-80%最佳
innodb_flush_log_at_trx_commit = 2
default-character-set=utf8
lower_case_table_names = 1
#
#
# * IMPORTANT
# If you make changes to these settings and your system uses apparmor, you may
# also need to also adjust /etc/apparmor.d/usr.sbin.mysqld.
#
user= mysql
socket= /var/run/mysqld/mysqld.sock
port= 3306
basedir= /usr
datadir= /var/lib/mysql
tmpdir= /tmp
skip-external-locking
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
bind-address= 192.168.0.140
#
# * Fine Tuning
#
key_buffer= 16M
max_allowed_packet= 16M
thread_stack= 192K
thread_cache_size = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover = BACKUP
#max_connections = 100
#table_cache = 64
#thread_concurrency = 10
#
# * Query Cache Configuration
#
query_cache_limit= 1M
query_cache_size = 16M
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file = /var/log/mysql/mysql.log
#general_log = 1
log_error = /var/log/mysql/error.log
# Here you can see queries with especially long duration
#log_slow_queries= /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
# other settings you may need to change.
server-id= 1
log_bin= /var/log/mysql/mysql-bin.log
expire_logs_days= 10
max_binlog_size = 100M
#binlog_do_db= include_database_name
binlog_ignore_db= db_lobbylog
binlog_ignore_db= mysql
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem
[mysqldump]
quick
quote-names
max_allowed_packet= 16M
[mysql]
#no-auto-rehash# faster start of mysql but no tab completition
[isamchk]
key_buffer= 16M
#
# * IMPORTANT: Additional settings that can override those from this file!
# The files must end with '.cnf', otherwise they'll be ignored.
#
!includedir /etc/mysql/conf.d/
二.
MYSQL数据库复制跳过错误
在MYSQL进行Replication的时候，有时候会由于主从端的POS点不同，导致复制的SQL进程出现错误，从而导致主从复制失败。比如在主端复制一个ID是100的到从端，而此时由于某种原因从端已经有了ID=100的记录，这时进行INSERT操作的时候，就会主键重复，插入失败。这时候需要跳过这条错误。方法如下
1：停止SLAVE 服务
mysql> STOP SLAVE;
2：设置跳过的EVENT个数
mysql> SET GLOBAL SQL_SLAVE_SKIP_COUNTER = 1;
3：启动SLAVE服务
mysql> START SLAVE;
下面阐述下N的意思，转帖
大家都知道，当slave出现错误时，可以通过SET GLOBAL sql_slave_skip_counter = N来跳过错误，但是这个N，又真正代表什么呢，开始时，
理解错了，以为对于事务型，N代表N个事务，而非事务型，代表一条sql 语句。后经过linuxtone曹哥指导发现，其实并不是这么回事
文档中有介绍说（http://dev.mysql.com/doc/refman/ ... e-skip-counter.html）：
This statement skips the next N events from the master
即他是跳过N个events，这里最重要的是理解event的含义
在mysql中，对于sql的 binary log 他实际上是由一连串的event组成的一个组，即事务组。
我们在master上可以通过
SHOW BINLOG EVENTS 来查看一个sql里有多少个event。
通过例子来说明下，真正的event的含义：
在slave上
show slave status
Last_Errno: 1062
Last_Error: Error 'Duplicate entry '193' for key 'PRIMARY'' on query. Default database: 'ssldb'. Query: 'insert slave_no_skip1 values (193,'y10')'
Skip_Counter: 0
在 master 上，执行
mysql> SHOW BINLOG EVENTS in 'mysql-bin.000010' from 46755013;
+------------------+----------+------------+-----------+-------------+--------------------------------------------------------+
| Log_name | Pos | Event_type | Server_id | End_log_pos | Info |
+------------------+----------+------------+-----------+-------------+--------------------------------------------------------+
| mysql-bin.000010 | 46755013 | Query | 1 | 46755082 | BEGIN |
1| mysql-bin.000010 | 46755082 | Query | 1 | 46755187 | use `ssldb`; insert slave_no_skip1 values (193,'y10') |
2| mysql-bin.000010 | 46755187 | Xid | 1 | 46755214 | COMMIT /* xid=4529451 */ |
3| mysql-bin.000010 | 46755214 | Query | 1 | 46755283 | BEGIN |
4| mysql-bin.000010 | 46755283 | Query | 1 | 46755387 | use `ssldb`; insert slave_no_skip1 values (194,'y11') |
5| mysql-bin.000010 | 46755387 | Xid | 1 | 46755414 | COMMIT /* xid=4529452 */ |
6| mysql-bin.000010 | 46755414 | Query | 1 | 46755483 | BEGIN |
7| mysql-bin.000010 | 46755483 | Query | 1 | 46755587 | use `ssldb`; insert slave_no_skip1 values (195,'y12') |
8| mysql-bin.000010 | 46755587 | Xid | 1 | 46755614 | COMMIT /* xid=4529453 */ |
9| mysql-bin.000010 | 46755614 | Query | 1 | 46755683 | BEGIN |
10| mysql-bin.000010 | 46755683 | Query | 1 | 46755788 | use `ssldb`; insert slave_no_skip1 values (196,'y13') |
11| mysql-bin.000010 | 46755788 | Xid | 1 | 46755815 | COMMIT /* xid=4529454 */ |
12| mysql-bin.000010 | 46755815 | Query | 1 | 46755884 | BEGIN |
13| mysql-bin.000010 | 46755884 | Query | 1 | 46755989 | use `ssldb`; insert slave_no_skip1 values (197,'y14') |
14| mysql-bin.000010 | 46755989 | Xid | 1 | 46756016 | COMMIT /* xid=4529455 */ |
15| mysql-bin.000010 | 46756016 | Query | 1 | 46756085 | BEGIN |
16| mysql-bin.000010 | 46756085 | Query | 1 | 46756190 | use `ssldb`; insert slave_no_skip1 values (198,'y15') |
17| mysql-bin.000010 | 46756190 | Xid | 1 | 46756217 | COMMIT /* xid=4529456 */ |
18| mysql-bin.000010 | 46756217 | Query | 1 | 46756286 | BEGIN |
19| mysql-bin.000010 | 46756286 | Query | 1 | 46756391 | use `ssldb`; insert slave_no_skip1 values (199,'y16') |
20| mysql-bin.000010 | 46756391 | Xid | 1 | 46756418 | COMMIT /* xid=4529457 */ |
21| mysql-bin.000010 | 46756418 | Query | 1 | 46756487 | BEGIN |
| mysql-bin.000010 | 46756487 | Query | 1 | 46756592 | use `ssldb`; insert slave_no_skip1 values (190,'y17') |
| mysql-bin.000010 | 46756592 | Xid | 1 | 46756619 | COMMIT /* xid=4529458 */ |
+------------------+----------+------------+-----------+-------------+--------------------------------------------------------+
24 rows in set (0.00 sec)
通过错误可知，他是use `ssldb`; insert slave_no_skip1 values (193,'y10') 这条语句导致错误了
如果我们想跳到最后一条语句“use `ssldb`; insert slave_no_skip1 values (190,'y17')“的话 ，我们必须简单计算下中间有多少个event
很明显，是21，那么我们可以执行SET GLOBAL sql_slave_skip_counter =21（这里你SET GLOBAL sql_slave_skip_counter =19或者20都可以）
在slave 在次执行show slave status查看
Last_Errno: 1062
Last_Error: Error 'Duplicate entry '190' for key 'PRIMARY'' on query. Default database: 'ssldb'. Query: 'insert slave_no_skip1 values (190,'y17')'
Skip_Counter: 0
可见 他已经如我所愿，跳到use `ssldb`; insert slave_no_skip1 values (190,'y17')这里了。