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mk-slave-move.1p

NAME

mk-slave-move - Move a MySQL slave around in the replication hierarchy.

SYNOPSIS

  mk-slave-move slave --sibling-of-master
  mk-slave-move slave --slave-of-sibling sibling
  mk-slave-move slave --slave-of-uncle uncle
 
 

DESCRIPTION

This tool knows how to disconnect and reconnect slaves to each other, compare replication positions, and so on. This makes it able to move a slave around the replication hierarchy safely and correctly. It doesn't do anything you can't do by hand, but it is tedious and error-prone to do this by hand.

Some of the features are incomplete, including some safety checks such as not moving slaves that have temporary tables open.

The slave host can be specified using one of two methods. The first method is to use at least one of the standard connection-related command line options: ``--defaults-file'', ``--password'', ``--host'', ``--port'', ``--socket'' or ``--user''. These options only apply to the slave host.

The second method to specifiy the slave host, or the sibling or uncle host, is a DSN. A DSN is a special syntax that can be either just a hostname (like "server.domain.com" or 1.2.3.4), or a "key=value,key=value" string. Keys are a single letter:

    KEY MEANING
    === =======
    h   Connect to host
    P   Port number to use for connection
    S   Socket file to use for connection
    u   User for login if not current user
    p   Password to use when connecting
    F   Only read default options from the given file
 
 

If you omit any values in the sibling or uncle host, they are filled in with defaults from the slave host, so you don't need to specify them in both places. "mk-slave-move" reads all normal MySQL option files, such as ~/.my.cnf, so you may not need to specify username, password and other common options at all.

DOWNLOADING

You can download Maatkit from Google Code at <http://code.google.com/p/maatkit/>, or you can get any of the tools easily with a command like the following:

    wget http://www.maatkit.org/get/toolname
    or
    wget http://www.maatkit.org/trunk/toolname
 
 

Where "toolname" can be replaced with the name (or fragment of a name) of any of the Maatkit tools. Once downloaded, they're ready to run; no installation is needed. The first URL gets the latest released version of the tool, and the second gets the latest trunk code from Subversion.

OPTIONS

Specify one and only one of --sibling-of-master, --slave-of-sibling, --slave-of-uncle, or --detach.

--ask-pass

Prompt for a password when connecting to MySQL.

--charset

short form: -A; type: string

Default character set.

Enables character set settings in Perl and MySQL. If the value is "utf8", sets Perl's binmode on STDOUT to utf8, passes the "mysql_enable_utf8" option to DBD::mysql, and runs "SET NAMES UTF8" after connecting to MySQL. Any other value sets binmode on STDOUT without the utf8 layer, and runs "SET NAMES" after connecting to MySQL.

--config

type: Array

Read this comma-separated list of config files; if specified, this must be the first option on the command line.

--defaults-file

short form: -F; type: string

Only read mysql options from the given file.

--detach

Make this server forget that it is a slave.

--help

Show help and exit.

--host

short form: -h; type: string

Connect to host.

--password

short form: -p; type: string

Password to use when connecting.

--port

short form: -P; type: int

Port number to use for connection.

--set-vars

type: string; default: wait_timeout=10000

Set these MySQL variables.

Specify any variables you want to be set immediately after connecting to MySQL. These will be included in a "SET" command.

--sibling-of-master

Make the server a slave of its grandparent, so it is a sibling of its master.

The procedure is as follows:

  1. Connect to the server's master.
  2. Stop the slave processes on the master.
  3. Wait for the server to catch up to its master in replication.
  4. Point the slave to the master's master.
 
 

--slave-of-sibling

Make the server a slave of one of its siblings. Specify the sibling as a DSN.

The procedure is as follows:

  1. Connect to the sibling and verify that it has the same master.
  2. Stop the slave processes on the server and its sibling.
  3. If one of the servers is behind the other, make it catch up.
  4. Point the slave to its sibling.
 
 

--slave-of-uncle

Make the server a slave of one of its uncles (parent's siblings). Specify the uncle as a DSN.

An ``uncle'' is a sibling of the server's master. The procedure is as follows:

  1. Connect to the slave's master and its uncle, and verify that both have the
     same master.  (Their common master is the slave's grandparent).
  2. Stop the slave processes on the master and uncle.
  3. If one of them is behind the other, make it catch up.
  4. Point the slave to its uncle.
 
 

--socket

short form: -S; type: string

Socket file to use for connection.

--timeout

type: time; default: 10m

Timeout when waiting for replication to catch up.

--user

short form: -u; type: string

User for login if not current user.

--version

Show version and exit.

TODO

The following options are not implemented yet.

--promote

Make the server a slave of its grandparent, if any, and then make all of its previous siblings its slaves. If extra DSNs are given on the command-line, use these as its siblings; otherwise discover siblings by examining its master.

--resume

Start the slave running after moving it. Default is to leave the slave stopped. TODO: this option is not implemented yet.

--slave-of-master

TODO: change to current master. Can be useful for throwing away corrupt relay logs, for example. Note: must check error log and see what the real position of the log file is. http://www.pythian.com/blogs/876/when-show-slave-status-and-the-error-log-disagree

SYSTEM REQUIREMENTS

You need Perl, DBI, DBD::mysql, and some core packages that ought to be installed in any reasonably new version of Perl.

EXIT STATUS

Successful exit status is 0. Any other value represents the exit status of the Perl process itself.

ENVIRONMENT

The environment variable "MKDEBUG" enables verbose debugging output in all of the Maatkit tools:

    MKDEBUG=1 mk-....
 
 

BUGS

Please use Google Code Issues and Groups to report bugs or request support: <http://code.google.com/p/maatkit/>.

Please include the complete command-line used to reproduce the problem you are seeing, the version of all MySQL servers involved, the complete output of the tool when run with ``--version'', and if possible, debugging output produced by running with the "MKDEBUG=1" environment variable.

SEE ALSO

See also mk-table-checksum, mk-table-sync, mk-slave-delay.

COPYRIGHT, LICENSE AND WARRANTY

This program is copyright 2007-2009 Baron Schwartz. Feedback and improvements are welcome.

THIS PROGRAM IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2; OR the Perl Artistic License. On UNIX and similar systems, you can issue `man perlgpl' or `man perlartistic' to read these licenses.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

AUTHOR

Baron Schwartz

VERSION

This manual page documents Ver 0.9.7 Distrib 3519 $Revision: 3451 $.