How to run multiple MySQL instances in one server

4 minute read


  • System: Ubuntu 14.04
  • Mysql-server: 5.5+


Use separate my.cnf


  • copy the original my.cnf as my2.cnf;
  • Update pid-file, socket, port and datadir in my2.cnf;
  • Run sudo mysql_install_db --user=mysql --datadir=/var/lib/mysql2;
  • start the second mysql server with mysqld_safe --defaults-file=/etc/mysql/my2.cnf, then you will have two server running.

Pros and Cons

  • Easy, use less effort to achieve;
  • Not good to control, need write a new service command to handle start/stop/etc.

Use mysqld_multi


  • Run mysqld_multi --example to show all codes we will use;
  • Copy and Update mysqld_multi section in my.cnf;
  • Update group name mysqld to mysqld1(make original instance controlled by mysqld_multi) in my.cnf;
  • Add new group mysqld2 in my.cnf with user, pid-file, socket, port and datadir.
  • Run sudo mysql_install_db --user=mysql --datadir=/var/lib/mysql2;
  • Use command mysqld_multi  to manage(start/stop ) all instances.

Pros and Cons

  • Easy, a little more than the first one;
  • Easy to control, command mysqld_multi  build-in with mysql.


  • In MySQL 5.6, when you run mysql_install_db, you might get an error that says FATAL ERROR: Could not find my-default.cnf. Fix it by sudo cp /etc/mysql/my.cnf /usr/share/mysql/my-default.cnf.
  • You may see [Warning] Can't create test file /var/lib/mysql2/ip-xxx.lower-test, this is because Ubuntu’s security check, Fix it by disable MySQL security check:
    • sudo ln -s /etc/apparmor.d/usr.sbin.mysqld /etc/apparmor.d/disable/
    • sudo apparmor_parser -R /etc/apparmor.d/usr.sbin.mysqld