环境
Linux 系统：redhat as4.5
Mysql 版本：mysql 4.1.22
星期一上班，就听到 开发说一台mysql数据库down掉（此台数据库只做备份用）。连上系统，用ps -ef |grep mysql查看下进程，果真以个进程都没有。那就重启mysql服务，呀启动不起来。就查看mysql的错误日志。
InnoDB: Doing recovery: scanned up to log sequence number 0 48155
InnoDB: Last MySQL binlog file position 0 79, file name /var/log/mysql/updatelog.000006
100621 5:36:33 InnoDB: Flushing modified pages from the buffer pool...
100621 5:36:33 InnoDB: Started; log sequence number 0 48155
100621 5:36:34 [ERROR] /mysql/libexec/mysqld: Error writing file '/data/db2.ihome.com.pid' (Errcode: 28)
100621 5:36:34 [ERROR] Can't start server: can't create PID file: No space left on device
Number of processes running now: 0
100621 05:36:34 mysqld restarted
/mysql/libexec/mysqld: Error writing file './db2-slow.log' (Errcode: 28)
100621 5:36:34 [ERROR] Could not use db2-slow.log for logging (error 28). Turning logging off for the whole duration of the MySQL server process. To turn it on again: fix the cause, shutdown the MySQL server and restart it.
100621 5:36:34 InnoDB: Database was not shut down normally!
哦原来磁盘空间满了，使用df -h 查看下，存放data的目录已经使用100%.进入data目录查看。原来是一个备份数据库文件在里面占用的了大量的磁盘空间。查看备份脚本原来是备份脚本里面的路径写错了。修改路径，把备份文件移动到备份目录。启动mysql服务正常启动。
使用命令登陆上mysql，发现主从已经不同步了。查看mysql的错误日志得到
100621 9:32:21 [Note] Slave SQL thread initialized, starting replication in log 'mysql-bin.000023' at position 211845, relay log './db2-relay-bin.000013' position: 217010
100621 9:32:21 [ERROR] Error in Log_event::read_log_event(): 'read error', data_len: 112, event_type: 2
100621 9:32:21 [ERROR] Error reading relay log event: slave SQL thread aborted because of I/O error
100621 9:32:21 [ERROR] Slave: Could not parse relay log event entry. The possible reasons are: the master's binary log is corrupted (you can check this by running 'mysqlbinlog' on the binary log), the slave's relay log is corrupted (you can check this by running 'mysqlbinlog' on the relay log), a network problem, or a bug in the master's or slave's MySQL code. If you want to check the master's binary log or slave's relay log, you will be able to know their names by issuing 'SHOW SLAVE STATUS' on this slave. Error_code: 0
100621 9:32:21 [ERROR] Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'mysql-bin.000023' position 211845
首先想到尝试着手动来解决主从同步。连接上数据库
[root@db2 data]# mysql -u root -p
Enter password: 输入密码
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 55 to server version: 4.1.12-log
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> change master to
mysql->MASTER_LOG_POS=211845
mysql ->MASTER_LOG_FILE = 'mysql-bin.000023';
mysql>start slave;
mysql>show slave status\G;
查看同步依然是不成功。继续查看mysql 错误日志
100621 9:41:35 [Note] Slave SQL thread initialized, starting replication in log 'binglog mysql-bin.000023' at position 211845, relay log './db2-relay-bin.000001' position: 4
100621 9:41:35 [Note] Slave I/O thread: connected to master 'repl@192.168.1.41:3306', replication started in log 'binglog mysql-bin.000023' at position 211845
100621 9:41:35 [ERROR] Error reading packet from server: Could not find first log file name in binary log index file (server_errno=1236)
100621 9:41:35 [ERROR] Got fatal error 1236: 'Could not find first log file name in binary log index file' from master when reading data from binary log
100621 9:41:35 [ERROR] Slave I/O thread exiting, read up to log 'binglog mysql-bin.000023', position 211845
删除掉data目录下文件
db2-relay-bin.000001
db2-relay-bin.index
master.info
relay-log.info # 这些文件里面存放着同步时的信息。
然后重启下mysql 服务，查看同步信息。问题依旧。
然后 查看上次错误日志 与此次的错误日志。找不到 log文件，连接上主的mysql数据库。查看mysql信息一切正常。
#mysqlbinlog --start-position=211845 mysql-bin.000023 > a.sql
把从 211845到现在不同步的二进制文件导入到一个文本文件里面。然后使用scp 传到从数据库上
scp a.sql root@192.168.1.43:/ 输入密码自动copy到mysql 从服务器上的根目录下。
打开a.sql 查看最后一行的
然后到从数据库上 停止mysql slave 服务。stop slave
使用#mysql -uuser -p passwd database < /a.sql #手动导入没有同步的数据
导入完成之后 删除掉 db2-relay-bin.000001 db2-relay-bin.index master.info relay-log.info 这些文件。 使用
mysql>stop slave ;
mysql>change master to MASTER_LOG_POS = 155383248 MASTER_LOG_FILE = 'mysql-bin.000023';
Query OK, 0 rows affected (0.01 sec)
然后重启mysql服务，service mysqld restart
启动slave
mysql>start slave;
查看mysql主从状态mysql>show slave status\G;
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
看到这两行状态为Yes我心甚慰。看到这两行为Yes表示已经开始同步数据了。
下面是
CHANGE MASTER TO语法
CHANGE MASTER TO master_def[,master_def] ...
master_def:
MASTER_HOST = 'host_name'
| MASTER_USER = 'user_name'
| MASTER_PASSWORD = 'password'
| MASTER_PORT =port_num
| MASTER_CONNECT_RETRY =count
| MASTER_LOG_FILE = 'master_log_name'
| MASTER_LOG_POS =master_log_pos
| RELAY_LOG_FILE = 'relay_log_name'
| RELAY_LOG_POS =relay_log_pos
| MASTER_SSL = {0|1}
| MASTER_SSL_CA = 'ca_file_name'
| MASTER_SSL_CAPATH = 'ca_directory_name'
| MASTER_SSL_CERT = 'cert_file_name'
| MASTER_SSL_KEY = 'key_file_name'
| MASTER_SSL_CIPHER = 'cipher_list'
可以更改从属服务器用于与主服务器进行连接和通讯的参数。
master_def:
MASTER_HOST = 'host_name'
| MASTER_USER = 'user_name'
| MASTER_PASSWORD = 'password'
| MASTER_PORT =port_num
| MASTER_CONNECT_RETRY =count
| MASTER_LOG_FILE = 'master_log_name'
| MASTER_LOG_POS =master_log_pos
| RELAY_LOG_FILE = 'relay_log_name'
| RELAY_LOG_POS =relay_log_pos
| MASTER_SSL = {0|1}
| MASTER_SSL_CA = 'ca_file_name'
| MASTER_SSL_CAPATH = 'ca_directory_name'
| MASTER_SSL_CERT = 'cert_file_name'
| MASTER_SSL_KEY = 'key_file_name'
| MASTER_SSL_CIPHER = 'cipher_list'
可以更改从属服务器用于与主服务器进行连接和通讯的参数。
MASTER_USER,MASTER_PASSWORD,MASTER_SSL,MASTER_SSL_CA,MASTER_SSL_CAPATH,MASTER_SSL_CERT,MASTER_SSL_KEY和MASTER_SSL_CIPHER用于向从属服务器提供有关如何与主服务器连接的信息。
本文转自holy2009 51CTO博客，原文链接:http://blog.51cto.com/holy2010/362339
