The easiest way is to run multiple servers on Unix is to compile them with different TCP/IP ports and Unix socket files so that each one is listening on different network interfaces. Compiling in different base directories for each installation also results automatically in a separate, compiled-in data directory, log file, and PID file location for each server.
Assume that an existing 5.0.19 server is configured for the
default TCP/IP port number (3306) and Unix socket file
/tmp/mysql.sock). To configure a new
5.5.4 server to have different operating parameters,
use a configure command something like this:
file_name must be different from the
default TCP/IP port number and Unix socket file path name, and the
--prefix value should specify an
installation directory different from the one under which the
existing MySQL installation is located.
If you have a MySQL server listening on a given port number, you can use the following command to find out what operating parameters it is using for several important configurable variables, including the base directory and Unix socket file name:
With the information displayed by that command, you can tell what option values not to use when configuring an additional server.
Note that if you specify
localhost as a host
name, mysqladmin defaults to using a Unix
socket file connection rather than TCP/IP. You can explicitly
specify the connection protocol to use by using the
You don't have to compile a new MySQL server just to start with a different Unix socket file and TCP/IP port number. It is also possible to use the same server binary and start each invocation of it with different parameter values at runtime. One way to do so is by using command-line options:
Another way to achieve a similar effect is to use environment variables to set the Unix socket file name and TCP/IP port number:
export MYSQL_UNIX_PORT MYSQL_TCP_PORTshell>
mysqld_safe --datadir=/path/to/datadir &
This is a quick way of starting a second server to use for testing. The nice thing about this method is that the environment variable settings apply to any client programs that you invoke from the same shell. Thus, connections for those clients are automatically directed to the second server.
For automatic server execution, the startup script that is executed at boot time should execute the following command once for each server with an appropriate option file path for each command:
Each option file should contain option values specific to a given server.
On Unix, the mysqld_multi script is another way to start multiple servers. See Section 4.3.4, “mysqld_multi — Manage Multiple MySQL Servers”.