Check that you do not already have another mysqld process

对于主从配置和启动网上可以看到大篇的案例和讲解，这里我遇到了几个棘手的问题，就是2台从服务器无法正常启动，实例起不来，原因是有人在晚上做服务器关闭的时候没有先关闭mysql服务，在关闭服务器，到时第二天无法启动！问题转接到我这里看了，仔细看错误日志，变可以看出端倪，以下是错误信息；

[root@CloneSlave01 data]# tail -100 CloneSlave01.err 
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
121211 10:03:27  InnoDB: Unable to open the first data file
InnoDB: Error in opening ./ibdata1
121211 10:03:27  InnoDB: Operating system error number 11 in a file operation.
InnoDB: Error number 11 means 'Resource temporarily unavailable'.
InnoDB: Some operating system error numbers are described at
InnoDB: http://dev.mysql.com/doc/refman/5.5/en/operating-system-error-codes.html
121211 10:03:27 InnoDB: Could not open or create data files.
121211 10:03:27 InnoDB: If you tried to add new data files, and it failed here,
121211 10:03:27 InnoDB: you should now edit innodb_data_file_path in my.cnf back
121211 10:03:27 InnoDB: to what it was, and remove the new ibdata files InnoDB created
121211 10:03:27 InnoDB: in this failed attempt. InnoDB only wrote those files full of
121211 10:03:27 InnoDB: zeros, but did not yet use them in any way. But be careful: do not
121211 10:03:27 InnoDB: remove old data files which contain your precious data!
121211 10:03:27 [ERROR] Plugin 'InnoDB' init function returned error.
121211 10:03:27 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
121211 10:03:27 [ERROR] Unknown/unsupported storage engine: innodb
121211 10:03:27 [ERROR] Aborting


121211 10:03:27 [Note] /usr/local/mysql/bin/mysqld: Shutdown complete


121211 10:03:27 mysqld_safe mysqld from pid file /usr/local/mysql/data/CloneSlave01.pid ended

以上的问题，需要剔除ibdata 以及ib_logfile0、ib_logfile1这3个文件便可以正常启动

121211 10:17:37 InnoDB: Completed initialization of buffer pool
InnoDB: The first specified data file ./ibdata1 did not exist:
InnoDB: a new database to be created!
121211 10:17:37  InnoDB: Setting file ./ibdata1 size to 10 MB
InnoDB: Database physically writes the file full: wait...
121211 10:17:37  InnoDB: Log file ./ib_logfile0 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile0 size to 5 MB
InnoDB: Database physically writes the file full: wait...
121211 10:17:38  InnoDB: Log file ./ib_logfile1 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile1 size to 5 MB
InnoDB: Database physically writes the file full: wait...
InnoDB: Doublewrite buffer not found: creating new
InnoDB: Doublewrite buffer created
InnoDB: 127 rollback segment(s) active.
InnoDB: Creating foreign key constraint system tables
InnoDB: Foreign key constraint system tables created
121211 10:17:38  InnoDB: Waiting for the background threads to start
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
121211 10:17:39 InnoDB: 1.1.7 started; log sequence number 0
121211 10:17:39 [ERROR] Can't start server: Bind on TCP/IP port: Address already in use
121211 10:17:39 [ERROR] Do you already have another mysqld server running on port: 3306 ?
121211 10:17:39 [ERROR] Aborting


121211 10:17:39  InnoDB: Starting shutdown...
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files

再次启动的时候可以看出有端口占用了3306导致无法启动，由于这是测试无关紧要，就没做端口变更；下面进行查看；

[root@CloneSlave01 data]# netstat -tpln |grep 3306
tcp        0      0 :::3306                     :::*                        LISTEN      3237/mysqld         
[root@CloneSlave01 data]# kill 3237
[root@CloneSlave01 data]# netstat -tpln |grep 3306
[root@CloneSlave01 data]# service mysqld restart
MySQL server PID file could not be found!                  [FAILED]
Starting MySQL..                                           [  OK  ]
[root@CloneSlave01 data]# service mysqld restart
Shutting down MySQL.                                       [  OK  ]
Starting MySQL..                                           [  OK  ]
[root@CloneSlave01 data]#

我们提出3306的占用端口，即可重新启动，看上面的效果，另一台的操作方法和步骤和以上大同小异，我就不再次贴出来，当然启动好以后还要测试相关的数据完整性等问题！

总结：我们在关闭服务器的时候，一定要了解服务器的有哪些服务，需要我们提前做好关闭的，才能保证我们数据的安全可靠。