How to change MySQL data directory to a new drive SSD in this case with minimal downtime?

Install a new drive, format, partition and mount it, say as ‘/ssd’.

1. Change directory to new partition/location

# cd /ssd

2. Create new MySQL directory.

mkdir mysql

3. Assign the MySQL group and owner for the new data directory.

# chown -R mysql:mysql /ssd/mysql

4. Sync all the databases from old data dir to new data dir.

# nohup rsync -vrplogDtH /var/lib/mysql/ /ssd/mysql &

(nohup insures that the copy command runs even if the shell hangs and the sync status will be available in nohup.out)

5. Schedule a MySQL server shutdown during off-peak hours.

# /etc/init.d/mysql(d) stop

(In Cpanel servers, stop chkservd too, else MySQL will be restarted, if monitoring is enabled).

6. Sync the data again (will take less time to sync this time).

# nohup rsync -vrplogDtH /var/lib/mysql/ /ssd/mysql &

7. Once you have verified the data, delete the “/var/lib/mysql” folder.

# rm -rf /var/lib/mysql

8. Create a symbolic link from the new data directory to the old one.

# ln -s /ssd/mysql /var/lib/mysql

Note: Create a symlink to avoid changing the MySQL socket and data path in MySQL, PHP and other applications that need it, or adjust the mysql config to see the new path