Shulou(Shulou.com)06/01 Report--

Cause of error in restarting MySQL database

[root@guoqing mysql] # service mysql restart

MySQL server PID file could not be found! [failure]

Starting MySQL...The server quit without updating PID file (/ usr/local/mysql/data/guoqing.pid). [failure]

There are many possible causes of problems, and the best way to find out exactly what causes them is to check the error log first:

1. It may be that / usr/local/mysql/data/guoqing.pid file does not have write permission

Solution: give permission, execute "chown-R mysql:mysql / usr/local/mysql/data"chmod-R 755 / usr/local/mysql/data" and then restart mysqld!

two。 The mysql process may already exist in the process.

Solution: use the command "ps-ef | grep mysqld" to see if there are any mysqld processes, and if so, use the "kill-9 process number" to kill, and then restart mysqld!

3. This may be the second time that mysql is installed on the machine, and there is residual data that affects the startup of the service.

Solution: go to mysql's data directory data. If mysql-bin.index exists, delete it as soon as possible. It's the culprit.

4.mysql will use the / etc/my.cnf configuration file when it starts without specifying a configuration file. Please open this file to see if there is a data directory (datadir) specified under the [mysqld] section.

Solution: please set this line under [mysqld]: datadir = / usr/local/mysql/data

5.skip-federated field problem

Solution: check the / etc/my.cnf file to see if there are any skip-federated fields that have not been commented out, and if so, comment them out immediately.

6. Error log directory does not exist

Solution: use the "chown"chmod" command to give the mysql owner and permissions

7.selinux caused the disaster. If it is centos system, selinux will be enabled by default.

Solution: close it, open / etc/selinux/config, change SELINUX=enforcing to SELINUX=disabled, then save and exit and restart the machine.

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