ubuntu

1. Stop MySQL using the following command:

   sudo /etc/init.d/mysql stop

2. Copy the existing data directory (default located in /var/lib/mysql) using the following command:

   sudo cp -R -p /var/lib/mysql /newpath

3. edit the MySQL configuration file with the following command:

   sudo gedit /etc/mysql/my.cnf

4. Look for the entry for datadir, and change the path (which should be /var/lib/mysql) to the new data directory.

5. In the terminal, enter the command:

   sudo gedit /etc/apparmor.d/usr.sbin.mysqld

6. Look for lines beginning with /var/lib/mysql. Change /var/lib/mysql in the lines with the new path.

7. Save and close the file.

8. Restart the AppArmor profiles with the command:

   sudo /etc/init.d/apparmor reload

9. Restart MySQL with the command:

   sudo /etc/init.d/mysql restart

10. Now login to MySQL and you can access the same databases you had before.

 

来源： 

 

centos:

• 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 /srv/mysql/

# chown mysql:mysql /srv/mysql

Moving the original data files

 # mv /var/lib/mysql/* /srv/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=/srv/mysql

and

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

to

socket=/srv/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 /srv/mysql.

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

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

# restorecon -Rv /srv/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 = /srv/mysql/mysql.sock

Optionally you can just use

$ mysql -u root -p --protocol tcp

to avoid connecting via the socket.