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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.
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 9.2.2, "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 10, "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
mysqld_multi supports the following options:
o --help
Display a help message and exit.
o --config-file=name
Specify the name of an alternative option file. This 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.
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 pathname of
the directory where the server is located. (See the descriptions for
these options in mysqld_safe(1).) Example:
[mysqld38]
mysqld = mysqld-max
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. This option was added in MySQL 4.1.6.
o --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.
o --user=user_name
The username of the MySQL account to use when invoking mysqladmin.
o --verbose
Be more verbose. This option was added in MySQL 4.1.6.
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 10, "Running Multiple MySQL Servers on the Same
Machine".
o 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 4.5, "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 username 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 usernames or passwords for the administrative accounts,
you might want to create an account on each server that has the same
username 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 5.2, "How the Privilege System Works". You have to do
this for each mysqld server. Change the connection parameters
appropriately when connecting to each one. Note that the hostname
part of the account name must allow 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.
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. 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`
# 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 test performed by these lines should be successful, or you might
encounter problems. See mysqld_safe(1).
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 root user.
Having the option in the option file does not matter; you merely 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 3.2, "Using Option Files".
SEE ALSO
isamchk(1), isamlog(1), msql2mysql(1), myisamchk(1), myisamlog(1),
myisampack(1), mysql(1), mysql.server(1), mysql_config(1),
mysql_fix_privilege_tables(1), mysql_zap(1), mysqlaccess(1),
mysqladmin(1), mysqlbinlog(1), mysqlcheck(1), mysqld(1),
mysqld_safe(1), mysqldump(1), mysqlhotcopy(1), mysqlimport(1),
mysqlshow(1), pack_isam(1), perror(1), replace(1), safe_mysqld(1)
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
MySQL AB (http://www.mysql.com/). This software comes with no
warranty.
MySQL 4.1 01/27/2006 MYSQLD_MULTI(1)
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