mysqld_multi
MYSQLD_MULTI(1) MySQL Database System MYSQLD_MULTI(1)
NAME
mysqld_multi - manage multiple MySQL servers
SYNOPSIS
mysqld_multi [options] {start|stop|report} [GNR[,GNR] ...]
DESCRIPTION
mysqld_multi is designed to manage several mysqld processes that listen
for connections on different Unix socket files and TCP/IP ports. It can
start or stop servers, or report their current status.
Note
For some Linux platforms, MySQL installation from RPM or Debian
packages includes systemd support for managing MySQL server startup
and shutdown. On these platforms, mysqld_multi is not installed
because it is unnecessary. For information about using systemd to
handle multiple MySQL instances, see Section 2.5.9, "Managing MySQL
Server with systemd".
mysqld_multi searches for groups named [mysqldN] in my.cnf (or in the
file named by the --defaults-file option). N can be any positive
integer. This number is referred to in the following discussion as the
option group number, or GNR. Group numbers distinguish option groups
from one another and are used as arguments to mysqld_multi to specify
which servers you want to start, stop, or obtain a status report for.
Options listed in these groups are the same that you would use in the
[mysqld] group used for starting mysqld. (See, for example,
Section 2.9.5, "Starting and Stopping MySQL Automatically".) However,
when using multiple servers, it is necessary that each one use its own
value for options such as the Unix socket file and TCP/IP port number.
For more information on which options must be unique per server in a
multiple-server environment, see Section 5.8, "Running Multiple MySQL
Instances on One Machine".
To invoke mysqld_multi, use the following syntax:
mysqld_multi [options] {start|stop|reload|report} [GNR[,GNR] ...]
start, stop, reload (stop and restart), and report indicate which
operation to perform. You can perform the designated operation for a
single server or multiple servers, depending on the GNR list that
follows the option name. If there is no list, mysqld_multi performs the
operation for all servers in the option file.
Each GNR value represents an option group number or range of group
numbers. The value should be the number at the end of the group name in
the option file. For example, the GNR for a group named [mysqld17] is
17. To specify a range of numbers, separate the first and last numbers
by a dash. The GNR value 10-13 represents groups [mysqld10] through
[mysqld13]. Multiple groups or group ranges can be specified on the
command line, separated by commas. There must be no whitespace
characters (spaces or tabs) in the GNR list; anything after a
whitespace character is ignored.
This command starts a single server using option group [mysqld17]:
mysqld_multi start 17
This command stops several servers, using option groups [mysqld8] and
[mysqld10] through [mysqld13]:
mysqld_multi stop 8,10-13
For an example of how you might set up an option file, use this
command:
mysqld_multi --example
mysqld_multi searches for option files as follows:
o With --no-defaults, no option files are read.
o With --defaults-file=file_name, only the named file is read.
o Otherwise, option files in the standard list of locations are read,
including any file named by the --defaults-extra-file=file_name
option, if one is given. (If the option is given multiple times,
the last value is used.)
For additional information about these and other option-file options,
see Section 4.2.2.3, "Command-Line Options that Affect Option-File
Handling".
Option files read are searched for [mysqld_multi] and [mysqldN] option
groups. The [mysqld_multi] group can be used for options to
mysqld_multi itself. [mysqldN] groups can be used for options passed
to specific mysqld instances.
The [mysqld] or [mysqld_safe] groups can be used for common options
read by all instances of mysqld or mysqld_safe. You can specify a
--defaults-file=file_name option to use a different configuration file
for that instance, in which case the [mysqld] or [mysqld_safe] groups
from that file are used for that instance.
mysqld_multi supports the following options.
o --help Display a help message and exit.
o --example Display a sample option file.
o --log=file_name Specify the name of the log file. If the file
exists, log output is appended to it.
o --mysqladmin=prog_name The mysqladmin binary to be used to stop
servers.
o --mysqld=prog_name The mysqld binary to be used. Note that you can
specify mysqld_safe as the value for this option also. If you use
mysqld_safe to start the server, you can include the mysqld or
ledir options in the corresponding [mysqldN] option group. These
options indicate the name of the server that mysqld_safe should
start and the path name of the directory where the server is
located. (See the descriptions for these options in
mysqld_safe(1).) Example:
[mysqld38]
mysqld = mysqld-debug
ledir = /opt/local/mysql/libexec
o --no-log Print log information to stdout rather than to the log
file. By default, output goes to the log file.
o --password=password The password of the MySQL account to use when
invoking mysqladmin. Note that the password value is not optional
for this option, unlike for other MySQL programs.
o --silent Silent mode; disable warnings.
o --tcp-ip Connect to each MySQL server through the TCP/IP port
instead of the Unix socket file. (If a socket file is missing, the
server might still be running, but accessible only through the
TCP/IP port.) By default, connections are made using the Unix
socket file. This option affects stop and report operations.
o --user=user_name The user name of the MySQL account to use when
invoking mysqladmin.
o --verbose Be more verbose.
o --version Display version information and exit.
Some notes about mysqld_multi:
o Most important: Before using mysqld_multi be sure that you
understand the meanings of the options that are passed to the
mysqld servers and why you would want to have separate mysqld
processes. Beware of the dangers of using multiple mysqld servers
with the same data directory. Use separate data directories, unless
you know what you are doing. Starting multiple servers with the
same data directory does not give you extra performance in a
threaded system. See Section 5.8, "Running Multiple MySQL Instances
on One Machine".
Important
Make sure that the data directory for each server is fully
accessible to the Unix account that the specific mysqld process
is started as. Do not use the Unix root account for this,
unless you know what you are doing. See Section 6.1.5, "How to
Run MySQL as a Normal User".
o Make sure that the MySQL account used for stopping the mysqld
servers (with the mysqladmin program) has the same user name and
password for each server. Also, make sure that the account has the
SHUTDOWN privilege. If the servers that you want to manage have
different user names or passwords for the administrative accounts,
you might want to create an account on each server that has the
same user name and password. For example, you might set up a common
multi_admin account by executing the following commands for each
server:
$> mysql -u root -S /tmp/mysql.sock -p
Enter password:
mysql> CREATE USER 'multi_admin'@'localhost' IDENTIFIED BY 'multipass';
mysql> GRANT SHUTDOWN ON *.* TO 'multi_admin'@'localhost';
See Section 6.2, "Access Control and Account Management". You have
to do this for each mysqld server. Change the connection parameters
appropriately when connecting to each one. Note that the host name
part of the account name must permit you to connect as multi_admin
from the host where you want to run mysqld_multi.
o The Unix socket file and the TCP/IP port number must be different
for every mysqld. (Alternatively, if the host has multiple network
addresses, you can set the bind_address system variable to cause
different servers to listen to different interfaces.)
o The --pid-file option is very important if you are using
mysqld_safe to start mysqld (for example, --mysqld=mysqld_safe)
Every mysqld should have its own process ID file. The advantage of
using mysqld_safe instead of mysqld is that mysqld_safe monitors
its mysqld process and restarts it if the process terminates due to
a signal sent using kill -9 or for other reasons, such as a
segmentation fault.
o You might want to use the --user option for mysqld, but to do this
you need to run the mysqld_multi script as the Unix superuser
(root). Having the option in the option file doesn't matter; you
just get a warning if you are not the superuser and the mysqld
processes are started under your own Unix account.
The following example shows how you might set up an option file for use
with mysqld_multi. The order in which the mysqld programs are started
or stopped depends on the order in which they appear in the option
file. Group numbers need not form an unbroken sequence. The first and
fifth [mysqldN] groups were intentionally omitted from the example to
illustrate that you can have "gaps" in the option file. This gives you
more flexibility.
# This is an example of a my.cnf file for mysqld_multi.
# Usually this file is located in home dir ~/.my.cnf or /etc/my.cnf
[mysqld_multi]
mysqld = /usr/local/mysql/bin/mysqld_safe
mysqladmin = /usr/local/mysql/bin/mysqladmin
user = multi_admin
password = my_password
[mysqld2]
socket = /tmp/mysql.sock2
port = 3307
pid-file = /usr/local/mysql/data2/hostname.pid2
datadir = /usr/local/mysql/data2
language = /usr/local/mysql/share/mysql/english
user = unix_user1
[mysqld3]
mysqld = /path/to/mysqld_safe
ledir = /path/to/mysqld-binary/
mysqladmin = /path/to/mysqladmin
socket = /tmp/mysql.sock3
port = 3308
pid-file = /usr/local/mysql/data3/hostname.pid3
datadir = /usr/local/mysql/data3
language = /usr/local/mysql/share/mysql/swedish
user = unix_user2
[mysqld4]
socket = /tmp/mysql.sock4
port = 3309
pid-file = /usr/local/mysql/data4/hostname.pid4
datadir = /usr/local/mysql/data4
language = /usr/local/mysql/share/mysql/estonia
user = unix_user3
[mysqld6]
socket = /tmp/mysql.sock6
port = 3311
pid-file = /usr/local/mysql/data6/hostname.pid6
datadir = /usr/local/mysql/data6
language = /usr/local/mysql/share/mysql/japanese
user = unix_user4
See Section 4.2.2.2, "Using Option Files".
COPYRIGHT
Copyright (C) 1997, 2023, Oracle and/or its affiliates.
This documentation is free software; you can redistribute it and/or
modify it only under the terms of the GNU General Public License as
published by the Free Software Foundation; version 2 of the License.
This documentation is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License along
with the program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see
http://www.gnu.org/licenses/.
SEE ALSO
For more information, please refer to the MySQL Reference Manual, which
may already be installed locally and which is also available online at
http://dev.mysql.com/doc/.
AUTHOR
Oracle Corporation (http://dev.mysql.com/).
MySQL 8.0 08/31/2023 MYSQLD_MULTI(1)
Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2024
Hurricane Electric.
All Rights Reserved.