It’s possible to run multiple instances of MySQL on the same machine, albeit running on a separate port. This guide attempts to explain quickly and easily how it’s done.

So what do we do? First things first, we need to make the data directory for the new mysql2 instance. That can be easily found from running ‘ps’ and identifying your current instance of mysql, let’s call it mysql1 in this case.

In my case, we had /var/lib/mysql, so I created mysql2:
mkdir /var/lib/mysql2
chown -R mysql.mysql /var/lib/mysql2

I also want some separate log file destinations:
mkdir /var/log/mysql2
chown -R mysql.mysql /var/log/mysql2

Then we get into the nitty gritty! Changing the my configuration file. That’s located on Debian systems in /etc/my.cnf and then I copied it to /etc/my2.cnf

In the new second config file, you need to specify a new port. Let’s say the default port for the first instance is 3306, I now should add “port=3307” into my2.cnf

The same rule will apply for changing the ‘datadir’ to the new directory in the config file, as well as the socket, you need to create a new connection socket for the secondary instance.

Also inside of the config file, you should specify where your new log-error file is as well as a new pid-file (if these are already in my.cnf, that is).

When you’re happy, just flick through the my2.cnf and double check that you’ve configured everything properly. Mine looked fine, so onto the next step.

run:
mysql_install_db –user=mysql –datadir=/var/lib/mysql2/

You’ll see some output on the command line, it should hopefully have no ERRORs in there. I also like to just double check my other instance of MySQL is still up and working OK using ps.

Now, let’s start our instance, shall we?
mysqld_safe –defaults-file=/etc/my2.cnf &

Verify it works:
mysql -S /var/lib/mysql2/mysql2.sock