This is a short article that explains how you change the default MySQL data directory and adjust SELinux to account for the changes. The article assumes that you’re running either RHEL, CentOS, Scientific Linux or Fedora with SELinux enabled. This works with the most recent EL (6.2) version.

We’ll be doing this in the following order.

Stopping the MySQL server
Create a new data directory and move the content from the old data directory
Correct the MySQL configuration file
Adjust SELinux parameters to accept our new change
Starting the MySQL server

Stopping the MySQL server

# service mysqld stop

Create a new data diretory and move the content from the old one
Creating a new data directory

# mkdir /data/mysql/

# chown mysql:mysql /data/mysql

Moving the original data files

 # mv /var/lib/mysql/* /data/mysql/

Ning: I going use cp for safe

 # cp -rp /var/lib/mysql/* /data/mysql/

Correct the MySQL configuration file

Edit the my.cnf file for your distribution. In my example it’s located in the /etc/mysql/ directory. RHEL/CentOS/Scientific Linux put the my.cnf file directly in /etc by default.

# nano /etc/mysql/my.cnf

Change

datadir=/var/lib/mysql

to

datadir=/data/mysql

and

socket=/var/lib/mysql/mysql.sock

to

socket=/data/mysql/mysql.sock

and save the file.
Adjust SELinux parameters to accept our new change

Should the following command output “Permissive” or “Disabled” then you may skip the details for SELinux.

# getenforce

Run the semanage command to add a context mapping for /data/mysql.

# semanage fcontext -a -t mysqld_db_t "/data/mysql(/.*)?"

Now use the restorecon command to apply this context mapping to the running system.

# restorecon -Rv /data/mysql

Starting the MySQL server

# service mysqld start

Verifying access and connectivity

$ mysql -u root -p

mysql> show databases;

If this is working, you’re up and running. Should you get a message that says

ERROR 2002 (HY000): Can’t connect to local MySQL server through socket ‘/var/lib/mysql/mysql.sock’

then add the following to your /etc/my.cnf

[client]
socket = /data/mysql/mysql.sock

Optionally you can just use

$ mysql -u root -p --protocol tcp

to avoid connecting via the socket.