How To Move MySQL Data Directory

Prerequisite: A free partition that will serve as a dedicated MySQL partition.

Note: These instructions assume that the partition you wish to mount is /dev/sdc1

1. Backup all MySQL databases
   Code:

   mysqldump --opt --all-databases | gzip > /home/alldatabases.sql.gz

2. Stop tailwatchd and the mysql (tailwatchd monitors services, so disable it to prevent it from prematurely restarting mysql)
   Code:

   /scripts/restartsrv_tailwatchd --stop
   /scripts/restartsrv_mysql --stop

3. Backup the MySQL data directory in case something goes awry
   Code:

   mv /var/lib/mysql /var/lib/mysql.backup

4. Create the new mount point
   Code:

   mkdir /var/lib/mysql

5. Configure /etc/fstab so that the new partition is mounted when the server boots (adjust values as necessary)
   Code:

   echo "/dev/sdc1     /var/lib/mysql     ext3     defaults,usrquota    0 1" >> /etc/fstab

6. Mount the new partition. The following command will mount everything in /etc/fstab:
   Code:

   mount -a

7. Change the ownership of the mount point so that it is accessible to the user “mysql”
   Code:

   chown mysql:mysql /var/lib/mysql

8. Ensure that the permissions of the mount point are correct
   Code:

   chmod 711 /var/lib/mysql

9. Start mysql and tailwatchd
   Code:

   /scripts/restartsrv_mysql --start
   /scripts/restartsrv_tailwatchd --start

10. Ensure that the MySQL data directory is mounted correctly:
    Code:

    mount |grep /var/lib/mysql

11. You should see a line that looks like this:
    /dev/sdc1 on /var/lib/mysql type ext3 (rw,usrquota)

Source