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(1)).
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 11, "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.
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.
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 11,
"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 5.5, "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 6.2, "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 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 3.2, "Using Option Files".
SEE ALSO
msql2mysql(1), myisamchk(1), myisamlog(1), myisampack(1),
mysql(1), mysql.server(1), mysql_config(1),
mysql_fix_privilege_tables(1), mysql_upgrade(1),
mysql_zap(1), mysqlaccess(1), mysqladmin(1),
mysqlbinlog(1), mysqlcheck(1), mysqld(1), mysqld_safe(1),
mysqldump(1), mysqlhotcopy(1), mysqlimport(1),
mysqlmanager(1), mysqlshow(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 5.0 03/04/2006 FBMYSQLD_MULTIFR(1)
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