SoFunction
Updated on 2025-04-03

mysqld_multi runs multiple MySQL instances on a Linux server

Use in Linuxmysqld_multiIt is a common practice to manage multiple MySQL instances. This method allows you to run multiple MySQL services on the same machine, each with different configurations and data directories. Below are detailed steps and code examples to help you achieve this goal.

1. Install MySQL

First, make sure your Linux system has MySQL installed. You can install MySQL using the following command:

sudo apt-get update
sudo apt-get install mysql-server

2. Configuration file

mysqld_multiUse one configuration file to manage multiple MySQL instances. Usually this configuration file is/etc/mysql/or/etc/. You need to add multiple instance configurations to this file.

Sample configuration file

[mysqld_multi]
mysqld = /usr/bin/mysqld_safe
mysqladmin = /usr/bin/mysqladmin
log = /var/log/mysqld_multi.log

[mysqld1]
socket = /var/run/mysqld/
pid-file = /var/run/mysqld/
datadir = /var/lib/mysql1
port = 3306
user = mysql
server-id = 1

[mysqld2]
socket = /var/run/mysqld/
pid-file = /var/run/mysqld/
datadir = /var/lib/mysql2
port = 3307
user = mysql
server-id = 2

3. Create a data directory

Create separate data directories for each instance and initialize them.

sudo mkdir -p /var/lib/mysql1
sudo mkdir -p /var/lib/mysql2
sudo chown -R mysql:mysql /var/lib/mysql1
sudo chown -R mysql:mysql /var/lib/mysql2

# Initialize the data directorysudo mysqld --initialize --user=mysql --basedir=/usr --datadir=/var/lib/mysql1
sudo mysqld --initialize --user=mysql --basedir=/usr --datadir=/var/lib/mysql2

4. Start and manage instances

usemysqld_multiCommands to start, stop, and manage these instances.

Start all instances

sudo mysqld_multi start

Start a specific instance

sudo mysqld_multi start 1
sudo mysqld_multi start 2

Stop all instances

sudo mysqld_multi stop

Stop a specific instance

sudo mysqld_multi stop 1
sudo mysqld_multi stop 2

Check instance status

sudo mysqld_multi report

5. Connect to a specific instance

You can usemysqlThe client connects to a specific instance. For example, an instance connected to port 3306:

mysql -u root -p -S /var/run/mysqld/

An instance connecting to port 3307:

mysql -u root -p -S /var/run/mysqld/

6. Things to note

  • Ensure that each instance isdatadir、socket、pid-fileThe configuration items are unique.
  • Make sure that the port numbers of each instance do not conflict.
  • Ensure that MySQL users have permission to access and write data directories.

Through the above steps, you can successfully start and manage multiple MySQL instances on Linux system. Hope this information will be helpful to you!

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