MySQL cannot start several common problems

high-protection server rental MySQL cannot start several common problems

Huaxia Alliance Network reviews: in the group to see a new classmate still ask MySQL can not start the problem, so summed up a few common situations and solutions, the need for friends can refer to.
yesterday in the group saw a new classmate still asked MySQL can not start the problem, so summed up a few common situations.
Issue 1: directory and file permissions are not set correctly
MySQL the $datadir directory, and its subordinate directory, the file permissions property is set incorrectly, which causes MySQL to not read and write files properly, unable to start.
error messages such as:
Copy the code code as follows : [Code]
Mysqld_safe starting mysqld daemon with databases From/usr/local/mysql/data
/usr/local/mysql/bin/mysqld_safe:line 107:/usr/local/mysql/data/imysql.local.err:permission denied

Issue 2: Port conflicts
Other mysqld instances have been started and the same port is occupied, and the port option needs to be modified .
error messages such as:
Copy the code code as follows :
[ERROR] Can ' t start server:bind on TCP/IP port:address already in use
[ERROR] Do you already has another MYSQLD server running on port:3306?
[ERROR] Aborting

Issue 3:innodb is not configured correctly
InnoDB the datafile,log file is not set correctly, resulting in a failure to start. In particular, the first time with the default parameters started, and later refer to some optimization guidelines, modified innodb parameters, will prompt different size, detailed errors such as:
Copy the code code as follows :
InnoDB:Error:log file./ib_logfile0 is of different size 0 5242880 bytes
Innodb:than specified in the. cnf file 0 134217728 bytes!
[ERROR] Plugin ' InnoDB ' init function returned error.
[ERROR] Plugin ' InnoDB ' registration as a STORAGE ENGINE failed.

Issue 4: mysql system library is not initialized
MySQL after installation, you need to run mysql_install_db to initialize the MySQL system library in order to start normally.
Issue 5: If you run mysql with normal user rights, you need to be aware of some directory permissions and user name password settings
sometimes in order to make MySQL more secure, we will run mysql low privilege, due to some security settings tools, You will need to reset the password for this user.

this time first listed the above several common problems, next time to add.
Typically, when the mysqld process fails to start, regardless of any errors, the error log is prioritized (the log file is typically in the $datadir/xx.err file, or /var/log/message,/var/log/mysql/mysqld.log , etc.), according to the error log prompt to find the cause of the problem, do not just look at the surface tips , such as the mysql.sock file cannot be found .  

Mid-Autumn Festival promotional activities come!!! Server Big Sale

8 Core 16 Threads 8G Memory 1T HDD 30G defense $999 per month

High anti-server G Port 16 core 8G memory, 30G protection, 20M bandwidth 800 yuan/month

Hunan IDC room   High anti-high with Baidu IP segment Dell Brand Server

G Port Access ! Stable! High-protection! Second Solution! Real defense!

Disregard cc, 7*24*365 hours after-sales operation and maintenance technical support

high-protection server rental server hosting VPS Large bandwidth cabinet Rental

Small new Reed: 2851506992 Reed 604906005 tell:15013023312

MySQL cannot start several common problems