Managing Multiple MySQL Instances on a Single Server

This article demonstrates how to run multiple MySQL instances on a single Linux server, each bound to a different port.

First, create separate data directories for the instances: mkdir -p /data/330{7,8,9}/data Then create a configuration file for each instance (e.g., /data/3307/my.cnf, /data/3308/my.cnf, /data/3309/my.cnf) with the following content, adjusting the paths and port numbers accordingly:

[mysqld]
basedir=/usr/local/mysql

datadir=/data/3307/data
socket=/data/3307/mysql.sock
log_error=/data/3307/mysql.log
port=3307
server_id=7
log_bin=/data/3307/mysql-bin

Repeat the same block for ports 3308 and 3309, changing the directory names, socket, log files, port, and server_id values.

Initialize each data directory (insecurely, for testing) with:

mysqld --initialize-insecure --user=mysql --basedir=/usr/local/mysql --datadir=/data/3307/data

mysqld --initialize-insecure --user=mysql --basedir=/usr/local/mysql --datadir=/data/3308/data

mysqld --initialize-insecure --user=mysql --basedir=/usr/local/mysql --datadir=/data/3309/data

If the directory already contains files, MySQL will abort with an error similar to:

2020-10-30T10:29:36.959026Z 0 [ERROR] --initialize specified but the data directory has files in it. Aborting.

After initialization, set proper ownership: chown -R mysql.mysql /data/* Manage the instances with systemd by copying the original service file and adjusting the ExecStart line to point to each instance's configuration:

cp mysqld.service mysqld3307.service
cp mysqld.service mysqld3308.service
cp mysqld.service mysqld3309.service

Verify the ExecStart entries:

ExecStart=/usr/local/mysql/bin/mysqld --defaults-file=/data/3307/my.cnf

ExecStart=/usr/local/mysql/bin/mysqld --defaults-file=/data/3308/my.cnf

ExecStart=/usr/local/mysql/bin/mysqld --defaults-file=/data/3309/my.cnf

Start each MySQL service:

systemctl start mysqld3307
systemctl start mysqld3308
systemctl start mysqld3309

Finally, confirm that each instance is listening on its designated port using netstat:

netstat -nltp
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp6       0      0 :::3307                 :::*                    LISTEN      10112/mysqld
tcp6       0      0 :::3308                 :::*                    LISTEN      10149/mysqld
tcp6       0      0 :::3309                 :::*                    LISTEN      10183/mysqld

With these steps, three independent MySQL servers run side‑by‑side on the same host.