MySQL数据同步【双主热备】
目录
- 应用环境
- 数据库同步方式
- 创建数据库表
- 配置数据库my.ini文件
- my.ini文件简单释义
- 配置双向同步
- 配置项释义
- 设置主机并启动从服务器线程
- show slave status </ul> </li>
- 测试同步
- 解决自增长列的问题
- 模拟测试自增长列解决方案
- 故障排除
- MySQL版本间复制兼容性问题
- ERROR 1201 (HY000) </ul> </li> </ul>
应用环境 数据库服务器
虚拟机
OS: Windows Server 2003
1.数据库服务器242
IP:192.168.206.242
2.数据库服务器243
IP:192.168.206.243
MySQL版本
版本号：5.5.2
查询语句：SELECT VERSION();
数据库同步方式 两台服务器互为主从，双向同步数据
创建数据库表 为试验双向同步，简单编写了一个创建数据库和一个用户表的语句。
并分别在服务器242和243上的MySQL中执行语句。
CREATE DATABASE wilsondb; USE wilsondb; DROP TABLE IF EXISTS `userinfo`; CREATE TABLE `userinfo` ( `UserId` int(11) NOT NULL AUTO_INCREMENT, `UserName` varchar(64) DEFAULT NULL, PRIMARY KEY (`UserId`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
配置数据库my.ini文件 在242和243服务器MySQL的安装目录下找到my.ini文件
my.ini详情及简单释义# MySQL Server Instance Configuration File # ---------------------------------------------------------------------- # Generated by the MySQL Server Instance Configuration Wizard # # # Installation Instructions # ---------------------------------------------------------------------- # # On Linux you can copy this file to /etc/my.cnf to set global options, # mysql-data-dir/my.cnf to set server-specific options # (@localstatedir@ for this installation) or to # ~/.my.cnf to set user-specific options. # # On Windows you should keep this file in the installation directory # of your server (e.g. C:\Program Files\MySQL\MySQL Server X.Y). To # make sure the server reads the config file use the startup option # "--defaults-file". # # To run run the server from the command line, execute this in a # command line shell, e.g. # mysqld --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" # # To install the server as a Windows service manually, execute this in a # command line shell, e.g. # mysqld --install MySQLXY --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" # # And then execute this in a command line shell to start the server, e.g. # net start MySQLXY # # # Guildlines for editing this file # ---------------------------------------------------------------------- # # In this file, you can use all long options that the program supports. # If you want to know the options a program supports, start the program # with the "--help" option. # # More detailed information about the individual options can also be # found in the manual. # # # CLIENT SECTION # ---------------------------------------------------------------------- # # The following options will be read by MySQL client applications. # Note that only client applications shipped by MySQL are guaranteed # to read this section. If you want your own MySQL client program to # honor these values, you need to specify it as an option during the # MySQL client library initialization. # # 客户端 [client] # 端口号 port=3306 [mysql] # 字符集 default-character-set=utf8 # SERVER SECTION # ---------------------------------------------------------------------- # # The following options will be read by the MySQL Server. Make sure that # you have installed the server correctly (see above) so it reads this # file. # [mysqld] # The TCP/IP Port the MySQL Server will listen on # MySQL端口号 port=3306 #Path to installation directory. All paths are usually resolved relative to this. # 安装路径 basedir="C:/Program Files/MySQL/MySQL Server 5.5/" #Path to the database root # 数据库根路径 datadir="C:/Documents and Settings/All Users/Application Data/MySQL/MySQL Server 5.5/Data/" # The default character set that will be used when a new schema or table is # created and no character set is defined # 字符集 character-set-server=utf8 # The default storage engine that will be used when create new tables when # 默认存储引擎 default-storage-engine=INNODB # Set the SQL mode to strict # 设置严格SQL模型 # 参数详细：http://www.cnblogs.com/ainiaa/archive/2010/12/31/1923002.html sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION" # The maximum amount of concurrent sessions the MySQL server will # allow. One of these connections will be reserved for a user with # SUPER privileges to allow the administrator to login even if the # connection limit has been reached. # 服务器端最大并发数，一个是留给超级管理员权限登录数据库 max_connections=100 # Query cache is used to cache SELECT results and later return them # without actual executing the same query once again. Having the query # cache enabled may result in significant speed improvements, if your # have a lot of identical queries and rarely changing tables. See the # "Qcache_lowmem_prunes" status variable to check if the current value # is high enough for your load. # Note: In case your tables change very often or if your queries are # textually different every time, the query cache may result in a # slowdown instead of a performance improvement. # 查询缓存的大小，Note：在查询常变，表结构常变的情况下，用缓存反而不好 query_cache_size=0 # The number of open tables for all threads. Increasing this value # increases the number of file descriptors that mysqld requires. # Therefore you have to make sure to set the amount of open files # allowed to at least 4096 in the variable "open-files-limit" in # section [mysqld_safe] # Table高速缓存的数量 table_cache=256 # Maximum size for internal (in-memory) temporary tables. If a table # grows larger than this value, it is automatically converted to disk # based table This limitation is for a single table. There can be many # of them. # 单张临时表的大小限制 tmp_table_size=26M # How many threads we should keep in a cache for reuse. When a client # disconnects, the client's threads are put in the cache if there aren't # more than thread_cache_size threads from before. This greatly reduces # the amount of thread creations needed if you have a lot of new # connections. (Normally this doesn't give a notable performance # improvement if you have a good thread implementation.) # 缓存多少线程给客户端使用 thread_cache_size=8 #*** MyISAM Specific options # The maximum size of the temporary file MySQL is allowed to use while # recreating the index (during REPAIR, ALTER TABLE or LOAD DATA INFILE. # If the file-size would be bigger than this, the index will be created # through the key cache (which is slower). # 重建索引时临时文件允许的最大值 myisam_max_sort_file_size=100G # If the temporary file used for fast index creation would be bigger # than using the key cache by the amount specified here, then prefer the # key cache method. This is mainly used to force long character keys in # large tables to use the slower key cache method to create the index. # 表发生变化重新排序需要的缓冲大小 myisam_sort_buffer_size=52M # Size of the Key Buffer, used to cache index blocks for MyISAM tables. # Do not set it larger than 30% of your available memory, as some memory # is also required by the OS to cache rows. Even if you're not using # MyISAM tables, you should still set it to 8-64M as it will also be # used for internal temporary disk tables. # MyISAM表索引缓存大小，建议不要超过可用内存的30% key_buffer_size=8M # Size of the buffer used for doing full table scans of MyISAM tables. # Allocated per thread, if a full scan is needed. # MyISAM表全表扫描时的缓冲区大小（顺序读取） read_buffer_size=64K # 随机读取的缓冲区大小 read_rnd_buffer_size=256K # This buffer is allocated when MySQL needs to rebuild the index in # REPAIR, OPTIMZE, ALTER table statements as well as in LOAD DATA INFILE # into an empty table. It is allocated per thread so be careful with # large settings. # 排序使用的缓冲区大小 sort_buffer_size=256K #*** INNODB Specific options *** # Use this option if you have a MySQL server with InnoDB support enabled # but you do not plan to use it. This will save memory and disk space # and speed up some things. #skip-innodb # Additional memory pool that is used by InnoDB to store metadata # information. If InnoDB requires more memory for this purpose it will # start to allocate it from the OS. As this is fast enough on most # recent operating systems, you normally do not need to change this # value. SHOW INNODB STATUS will display the current amount used. # 设置InnoDB存储引擎存放数据字典信息和内部数据结构的内存大小 innodb_additional_mem_pool_size=4M # If set to 1, InnoDB will flush (fsync) the transaction logs to the # disk at each commit, which offers full ACID behavior. If you are # willing to compromise this safety, and you are running small # transactions, you may set this to 0 or 2 to reduce disk I/O to the # logs. Value 0 means that the log is only written to the log file and # the log file flushed to disk approximately once per second. Value 2 # means the log is written to the log file at each commit, but the log # file is only flushed to disk approximately once per second. # N（N是后面设置的值）次事务提交或事务外的指令就需要把日志写入硬盘 innodb_flush_log_at_trx_commit=1 # The size of the buffer InnoDB uses for buffering log data. As soon as # it is full, InnoDB will have to flush it to disk. As it is flushed # once per second anyway, it does not make sense to have it very large # (even with long transactions). # 设置InnoDB存储引擎的事务日志使用的缓冲区 innodb_log_buffer_size=1520K # InnoDB, unlike MyISAM, uses a buffer pool to cache both indexes and # row data. The bigger you set this the less disk I/O is needed to # access data in tables. On a dedicated database server you may set this # parameter up to 80% of the machine physical memory size. Do not set it # too large, though, because competition of the physical memory may # cause paging in the operating system. Note that on 32bit systems you # might be limited to 2-3.5G of user level memory per process, so do not # set it too high. # 设置InnoDB存放索引和表数据的最大缓冲区大小 innodb_buffer_pool_size=147M # Size of each log file in a log group. You should set the combined size # of log files to about 25%-100% of your buffer pool size to avoid # unneeded buffer pool flush activity on log file overwrite. However, # note that a larger logfile size will increase the time needed for the # recovery process. # 一个InnoDB事条日志的大小 innodb_log_file_size=74M # Number of threads allowed inside the InnoDB kernel. The optimal value # depends highly on the application, hardware as well as the OS # scheduler properties. A too high value may lead to thread thrashing. # InnoDB最大并发线程数 innodb_thread_concurrency=8
PS: 上面的折叠代码试验在chrome浏览器下需要手动刷一下页面才能展开
242服务器上配置：
在[mysqld]这个Section中加入如下key/value对：
#---------------------------------------------
server-id=242
log-bin=mysql-bin
relay-log=relay-bin
relay-log-index=relay-bin-index
replicate-do-db=wilsondb
#---------------------------------------------
243服务器上配置：
在[mysqld]这个Section中加入如下key/value对：
#---------------------------------------------
server-id=243
log-bin=mysql-bin
relay-log=relay-bin
relay-log-index=relay-bin-index
replicate-do-db=wilsondb
#---------------------------------------------
① server-id：标识，唯一，值范围在：1至2^23-1
② log-bin：配置是否在数据库有变动时写二进制日志
查看日志是否开启：
show variables like '%bin';
③ relay-log：这个不太会解释，Master二进制日志到Slave的IO进程会写到relay-log最后一行，Slave的sql进程时刻监测着relay-log是否有变化，有变化则解析执行.
④ replicate-to-db:同步的数据库
⑤ 其它复制启动选项： http://dev.mysql.com/doc/refman/5.1/zh/replication.html#replication-options
在服务器242和243上配置好之后，分别重启MySQL服务，如果重启失败则说明配置有误!
设置主机并启动从服务器线程 服务242上用MySQL命令行工具执行如下语句：
mysql> stop slave;
mysql> change master to master_host='192.168.206.243',master_user='root',master_password='abcd';
mysql> start slave;
mysql> show slave status\G;
#master_host的最大长度为60
#master_user的最大长度为16
#master_password最大长度为32
服务243上上用MySQL命令行工具执行如下语句：
mysql> stop slave;
mysql> change master tomaster_host='192.168.206.242',master_user='root',master_password='abcd';
mysql> start slave;
mysql> show slave status\G;
① Slave_IO_Status:线程已经连接上主服务器，正等待二进制日志事件到达。如果主服务器正空闲，会持续较长的时间。如果等待持续slave_read_timeout秒，则发生超时。此时，线程认为连接被中断并企图重新连接。
更多Slave_IO_Status: http://dev.mysql.com/doc/refman/5.1/zh/replication.html#slave-io-thread-states
② Master_Host: 主机IP
③ Master_Log_File和Master_LOG_POS选项执行CHANGE MASTER TO来告诉从服务器重新从该点读取二进制日志
④ Slave_IO_Running:是否要从Master复制二进制数据
⑤ Slave_SQL_Running:是否执行从Master复制过来的二进制数据
⑥ Slave_IO_Running和Slave_SQL_Running的值均为Yes时为同步开启;
⑦ Last_Errno和Last_Error是错误信息的提示（如果有错误）
⑧ Seconds_Behind_Master：Slave的数据落后Master的多少秒，同步完成为0
测试同步 为了方便测试，装了一个Navicat for MySQL;
对242和243数据库进行了双向的增、删、改操作;
结果：最后都能正确的双向同步。
解决自增长列的问题 原因：当同步断开，两台服务器分别有新数据进入，那么主键ID是自增长列会出现冲突的情况，会导致同步无法继续。
在242和243服务器MySQL的安装目录下找到my.ini文件
分别在文件最后添入下面配置项：
服务器242：
#-------------------------------------
auto_increment_offset=1
auto_increment_increment=2
#-------------------------------------
服务器243：
#-------------------------------------
auto_increment_offset=2
auto_increment_increment=2
#-------------------------------------
查看修改后的属性值：
SHOW VARIABLES LIKE 'auto_inc%';
服务器242：
服务器243：
通过调整auto_increment_offset和auto_increment_increment让两台服务器自增长值不重复，这样多台服务器自增的问题就解决了;
（此项操作为了看自增更明显，我重新生成了表，然后再做了配置，其实本不需要重新生成表结构!）
模拟测试自增长列解决方案 测试过程模拟同步在断开后，两个数据库分别都有数据插入，然后再开启同步，是否会有自增ID的冲突。
1.先分别在服务器242和243上停止Slave线程
2.然后分别向服务器242和243所在数据库中分别插入数据
很明显，分别插入时，自增列也不会重复;
3.分别开启服务器242和243的Slave线程
4.查看同步后的数据
-------------------------------------------------------------
大功告成，同步成功，且没有发生冲突！
故障排除 试验过程中遇到几个主要问题：
官方是推荐使用最近的版本，复制功能在不断改进中，同时推荐主从服务器使用相同的版本;
为了避免出现一些兼容性的问题，这里两台数据库服务器上的MySQL安装了相同的版本;
不同MySQL版本之间的复制兼容性: http://dev.mysql.com/doc/refman/5.1/zh/replication.html#replication-compatibility
2.ERROR 1201 (HY000): Could not initialize master info structure; more error messages can be found in the MySQL error log
在start slave;时出现error 1201(HY000)，出错后注意用show slave status\G 看错误提示（Last_IO_Error和Last_SQL_Error）。后台根据提示定位是在没关掉同步的情况下进行了一些冲突的SQL操作，
解决步骤： ① 停止SQL服务
② 删除master.info和relay-log.info文件
③ change master to master_host='XXXXXX',
master_user='XXXX',master_password='XXXX';
④ 重启SQL服务器，再start slave;
过程中远不止遇到这几个错误，没记录下细节，都是看相关提示修正的，都是些操作问题或者是细心问题;
作 者： Porschev[钟慰]
出 处： http://www.cnblogs.com/zhongweiv/