mysqld_multi(1) — Linux manual page

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MYSQLD_MULTI(1)          MariaDB Database System         MYSQLD_MULTI(1)

NAME         top

       mysqld_multi - manage multiple MariaDB servers

SYNOPSIS         top

       mysqld_multi [options] {start|stop|report} [GNR[,GNR] ...]

DESCRIPTION         top

       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. 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.

       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 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. 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 will be used for that
       instance.

       mysqld_multi supports the following options.

       •   --help

           Display a help message and exit.

       •   --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 MariaDB account to use when invoking
           mysqladmin. Note that the password value is not optional for
           this option, unlike for other MariaDB programs.

       •   --silent

           Silent mode; disable warnings.

       •   --tcp-ip

           Connect to the MariaDB server(s) via the TCP/IP port instead
           of the UNIX socket. This affects stopping and reporting. If a
           socket file is missing, the server may still be running, but
           can be accessed only via the TCP/IP port. By default
           connecting is done via the UNIX socket. This option affects
           stop and report operations.

       •   --user=user_name

           The user name of the MariaDB account to use when invoking
           mysqladmin.

       •   --verbose

           Be more verbose.

       •   --version

           Display version information and exit.

       •   --wsrep-new-cluster

           Bootstrap a cluster.

       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.

       •   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.

       •   Make sure that the MariaDB 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´;

           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`
               # 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).

       •   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

COPYRIGHT         top

       Copyright 2007-2008 MySQL AB, 2008-2010 Sun Microsystems, Inc.,
       2010-2020 MariaDB Foundation

       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
       02110-1335 USA or see http://www.gnu.org/licenses/.

SEE ALSO         top

       For more information, please refer to the MariaDB Knowledge Base,
       available online at https://mariadb.com/kb/

AUTHOR         top

       MariaDB Foundation (http://www.mariadb.org/).

COLOPHON         top

       This page is part of the MariaDB (MariaDB database server)
       project.  Information about the project can be found at 
       ⟨http://mariadb.org/⟩.  If you have a bug report for this manual
       page, see ⟨https://mariadb.com/kb/en/mariadb/reporting-bugs/⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/MariaDB/server⟩ on 2021-08-27.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-08-26.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

MariaDB 10.6                   15 May 2020               MYSQLD_MULTI(1)