Friday, 12 December 2014

How to Change default MySQL Data Directory in Linux

As a System Administrator I don’t prefer to use / directory to store MySQL data files. Each time when I install MySQL for a production server, I tried to use secondary disk for storing application and database file. In that way I always change the default data directory of MySQL to secondary disk mounted on system.
Mostly MySQL uses /var/lib/mysql directory as default data directory for Linux based systems. Which are going to change to another location in this article.



Instruction’s to Change Default MySQL Data Directory:

Follow the below steps to make all the changes. In some cases service name, default data directory or MySQL configuration file path change. So use all the command as per you system settings.

1. Stop MySQL

Before making any changes, first make sure to stop mysql service
# service mysqld stop

2. Change Data Directory

Now copy default MySQL data directory (/var/lib/mysql) to other location as per your requirement. Also set the required MySQL ownership on new directory location. As per below command, we are relocating data directory to /data/mysql.
# cp -rap /var/lib/mysql /data/mysql
# chown mysql.mysql /data/mysql
Now edit MySQL default configuration file /etc/my.cnf and update values of datadir and socket variable.
Change From:
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

Change To: 
datadir=/data/mysql
socket=/data/mysql/mysql.sock

3. Start MySQL

After making all above changes. finally start MySQL service. Now it will use new data directory path
# service mysqld start
This article has been tested with CentOS 6.5 with MySQL 5.5.37. If you face any issue during MySQL startup check mysql log file /var/log/mysqld.log for any errors.