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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. The
MySQL Instance Manager is an alternative means of managing multiple servers (see mysqlmanager(8)).
mysqld_multi searches for groups named [mysqldN] in my.cnf (or in the file named by the --config-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 2.17.2.2, "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 5.6, "Running
Multiple MySQL Servers on the Same Machine".
To invoke mysqld_multi, use the following syntax:
shell> mysqld_multi [options] {start|stop|report} [GNR[,GNR] ...]
start, stop, 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]:
shell> mysqld_multi start 17
This command stops several servers, using option groups [mysqld8] and [mysqld10] through [mysqld13]:
shell> mysqld_multi stop 8,10-13
For an example of how you might set up an option file, use this command:
shell> mysqld_multi --example
As of MySQL 5.0.42, mysqld_multi searches for option files as follows:
With --no-defaults, no option files are read.
With --defaults-file=file_name, only the named file is read.
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.)
Option files read are searched for [mysqld_multi] and [mysqldN] option groups.
Before MySQL 5.0.42, the preceding options are not recognized. Files in the standard locations are
read, and any file named by the --config-file=file_name option, if one is given. A file named by
--config-file is read only for [mysqldN] option groups, not the [mysqld_multi] group.
mysqld_multi supports the following options:
--help
Display a help message and exit.
--config-file=file_name
As of MySQL 5.0.42, this option is deprecated. If given, it is treated the same way as
--defaults-extra-file, described earlier.
Before MySQL 5.0.42, this option specifies the name of an extra option file. It affects where
mysqld_multi looks for [mysqldN] option groups. Without this option, all options are read from the
usual my.cnf file. The option does not affect where mysqld_multi reads its own options, which are
always taken from the [mysqld_multi] group in the usual my.cnf file.
--example
Display a sample option file.
--log=file_name
Specify the name of the log file. If the file exists, log output is appended to it.
--mysqladmin=prog_name
The mysqladmin binary to be used to stop servers.
--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
--no-log
Print log information to stdout rather than to the log file. By default, output goes to the log
file.
--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.
--silent
Silent mode; disable warnings.
--tcp-ip
Connect to each MySQL server via 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 via the TCP/IP port.) By
default, connections are made using the Unix socket file. This option affects stop and report
operations.
--user=user_name
The user name of the MySQL account to use when invoking mysqladmin.
--verbose
Be more verbose.
--version
Display version information and exit.
Some notes about mysqld_multi:
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 5.6, "Running
Multiple MySQL Servers on the Same 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 5.3.5, "How to Run MySQL as a Normal User".
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:
shell> mysql -u root -S /tmp/mysql.sock -p
Enter password:
mysql> GRANT SHUTDOWN ON *.*
-> TO 'multi_admin'@'localhost' IDENTIFIED BY 'multipass';
See Section 5.4, "The MySQL Access Privilege System". 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 allow you to connect as multi_admin from the host where you want to run
mysqld_multi.
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 use --bind-address to cause
different servers to listen to different interfaces.)
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. Please note that the mysqld_safe script might require that you start it from a
certain place. This means that you might have to change location to a certain directory before
running mysqld_multi. If you have problems starting, please see the mysqld_safe script. Check
especially the lines:
----------------------------------------------------------------MY_PWD=`pwd` ---------------------------------------------------------------MY_PWD=`pwd`
MY_PWD=`pwd`
# Check if we are starting this relative (for the binary release)
if test -d $MY_PWD/data/mysql -a -f ./share/mysql/english/errmsg.sys -a \
-x ./bin/mysqld
----------------------------------------------------------------The ---------------------------------------------------------------The
The test performed by these lines should be successful, or you might encounter problems. See
mysqld_safe(1).
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 root user. 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 file should probably be in your home dir (~/.my.cnf)
# or /etc/my.cnf
# Version 2.1 by Jani Tolonen
[mysqld_multi]
mysqld = /usr/local/bin/mysqld_safe
mysqladmin = /usr/local/bin/mysqladmin
user = multi_admin
password = multipass
[mysqld2]
socket = /tmp/mysql.sock2
port = 3307
pid-file = /usr/local/mysql/var2/hostname.pid2
datadir = /usr/local/mysql/var2
language = /usr/local/share/mysql/english
user = john
[mysqld3]
socket = /tmp/mysql.sock3
port = 3308
pid-file = /usr/local/mysql/var3/hostname.pid3
datadir = /usr/local/mysql/var3
language = /usr/local/share/mysql/swedish
user = monty
[mysqld4]
socket = /tmp/mysql.sock4
port = 3309
pid-file = /usr/local/mysql/var4/hostname.pid4
datadir = /usr/local/mysql/var4
language = /usr/local/share/mysql/estonia
user = tonu
[mysqld6]
socket = /tmp/mysql.sock6
port = 3311
pid-file = /usr/local/mysql/var6/hostname.pid6
datadir = /usr/local/mysql/var6
language = /usr/local/share/mysql/japanese
user = jani
See Section 4.2.3.2, "Using Option Files".
COPYRIGHT
Copyright 2007-2008 MySQL AB, 2009 Sun Microsystems, Inc.
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
Sun Microsystems, Inc. (http://www.mysql.com/).
MySQL 5.0 05/07/2009 MYSQLD_MULTI(1)
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