MK-SLAVE-RESTART(1)

📦

version 7540 · 3 versions

mk-slave-restart 💖

okay bestie, gather round, because this one is a Perl script from the User Contributed Perl Documentation section of the manual, and it's called mk-slave-restart. She's a little chaotic, she's a little dangerous, and she is so useful when you actually need her. Let's get into it 💅

✨ NAME ✨

mk-slave-restart — watch and restart MySQL replication after errors. 🩹

No cap, that's the whole job description. She watches, she waits, she restarts.

🌸 SYNOPSIS 🌸

Usage: mk-slave-restart [OPTION...] [DSN]

mk-slave-restart watches one or more MySQL replication slaves for errors, and tries to restart replication if it stops. That's it. That's the vibe. 👑

⚠️ RISKS ⚠️

okay so this section exists to be honest with you, because the devs are not about to let you walk into this blind, and honestly? respect. 🫶

The following section is included to inform users about the potential risks, whether known or unknown, of using this tool. The two main categories of risks are those created by the nature of the tool (e.g. read-only tools vs. read-write tools) and those created by bugs.

So like, mk-slave-restart is a brute-force way to try to keep a slave server running when it is having problems with replication. Do not be too hasty to use it unless you need to. Seriously bestie. If you use this tool carelessly, you might miss the chance to really solve the slave server's problems. It's giving "putting a bandaid on a broken leg" energy. 😭

At the time of this release there is a bug that causes an invalid "CHANGE MASTER TO" statement to be executed. 💀

The authoritative source for updated information is always the online issue tracking system. Issues that affect this tool will be marked as such. You can see a list of such issues at the following URL: <http://www.maatkit.org/bugs/mk-slave-restart>.

Also, go peek at "BUGS" for more info on filing bugs and getting help. iykyk 🐛

💜 DESCRIPTION 💜

mk-slave-restart watches one or more MySQL replication slaves and tries to skip statements that cause errors. It polls slaves intelligently with an exponentially varying sleep time. You can specify errors to skip and run the slaves until a certain binlog position. slay. ✨

okay so real talk, a note from the author: it has come to his attention that Yahoo! had or has an internal tool called fix_repl, described to him by a past Yahoo! employee and mentioned in the first edition of High Performance MySQL. Apparently this tool does the same thing. But make no mistake, though: this is not a way to "fix replication." In fact he would not even encourage its use on a regular basis; he uses it only when he has an error he knows he just needs to skip past. periodt. 💅

👑 OUTPUT 👑

If you specify --verbose, mk-slave-restart prints a line every time it sees the slave has an error. See --verbose for details. (yes, it really is that straightforward, we love a self-referencing icon 🎀)

😴 SLEEP 😴

mk-slave-restart sleeps intelligently between polling the slave. The current sleep time varies. Not a fixed nap, a responsive nap. main character energy. 🌈

The initial sleep time is given by --sleep. ⏰
If it checks and finds an error, it halves the previous sleep time. ✂️
If it finds no error, it doubles the previous sleep time. 📈
The sleep time is bounded below by --min-sleep and above by --max-sleep. 🚧
Immediately after finding an error, mk-slave-restart assumes another error is very likely to happen next, so it sleeps the current sleep time or the initial sleep time, whichever is less. 🫢

🚪 EXIT STATUS 🚪

An exit status of 0 (sometimes also called a return value or return code) indicates success. 🎉

Any other value represents the exit status of the Perl process itself, or of the last forked process that exited if there were multiple servers to monitor. So if you're watching a whole lil squad of servers, the exit code you get back is from whoever left the group chat last. 🙈

🦋 COMPATIBILITY 🦋

mk-slave-restart should work on many versions of MySQL. Lettercase of many output columns from SHOW SLAVE STATUS has changed over time, so it treats them all as lowercase. lowercase is the vibe anyway. 💜

more coming bestie, don't go anywhere 🌸

✨ OPTIONS ✨

Okay bestie, buckle up, this is the big one. This tool takes extra command-line arguments on top of what you saw up top — go peek at the "SYNOPSIS" and the usage info if you want the deets. 💖

--always — Start slaves even when there is no error. Fair warning tho: with this option on, mk-slave-restart will not let you stop the slave manually if you want to! It said what it said. 💅
--ask-pass — Prompt for a password when connecting to MySQL.
--charset — short form: -A; type: string

Default character set. If the value is utf8, it 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.

--[no]check-relay-log — default: yes

Check the last relay log file and position before checking for slave errors.

By default, mk-slave-restart will not do anything (it will just sleep 😴) if neither the relay log file nor the relay log position have changed since the last check. This prevents infinite loops — like, restarting the same error in the same relay log file at the same relay log position, forever, no thank you.

For certain slave errors, however, this check needs to be disabled by specifying --no-check-relay-log. Do not do this unless you know what you are doing! 🚨

--config — type: Array

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

--daemonize — Fork to the background and detach from the shell. POSIX operating systems only.
--database — short form: -D; type: string

Database to use.

--defaults-file — short form: -F; type: string

Only read mysql options from the given file. You must give an absolute pathname.

--error-length — type: int

Max length of error message to print. When --verbose is set high enough to print the error, this option will truncate the error text to the specified length. This can be useful to prevent wrapping on the terminal. (your terminal said thank you 🫶)

--error-numbers — type: hash

Only restart this comma-separated list of errors. Makes mk-slave-restart only try to restart if the error number is in this comma-separated list of errors. If it sees an error not in the list, it will exit.

The error number is in the last_errno column of SHOW SLAVE STATUS.

--error-text — type: string

Only restart errors that match this pattern. A Perl regular expression against which the error text, if any, is matched. If the error text exists and matches, mk-slave-restart will try to restart the slave. If it exists but doesn't match, mk-slave-restart will exit.

The error text is in the last_error column of SHOW SLAVE STATUS.

--help — Show help and exit.
--host — short form: -h; type: string

Connect to host.

--log — type: string

Print all output to this file when daemonized.

--max-sleep — type: float; default: 64

Maximum sleep seconds.

The maximum time mk-slave-restart will sleep before polling the slave again. This is also the time that mk-slave-restart will wait for all other running instances to quit if both --stop and --monitor are specified.

See "SLEEP".

--min-sleep — type: float; default: 0.015625

The minimum time mk-slave-restart will sleep before polling the slave again. See "SLEEP".

--monitor — Whether to monitor the slave (default). Unless you specify --monitor explicitly, --stop will disable it.
--password — short form: -p; type: string

Password to use when connecting.

--pid — type: string

Create the given PID file when daemonized. The file contains the process ID of the daemonized instance. The PID file is removed when the daemonized instance exits. The program checks for the existence of the PID file when starting; if it exists and the process with the matching PID exists, the program exits.

--port — short form: -P; type: int

Port number to use for connection.

--quiet — short form: -q

Suppresses normal output (disables --verbose). 🤫

--recurse — type: int; default: 0

Watch slaves of the specified server, up to the specified number of servers deep in the hierarchy. The default depth of 0 means "just watch the slave specified."

mk-slave-restart examines SHOW PROCESSLIST and tries to determine which connections are from slaves, then connect to them. See --recursion-method.

Recursion works by finding all slaves when the program starts, then watching them. If there is more than one slave, mk-slave-restart uses fork() to monitor them.

This also works if you have configured your slaves to show up in SHOW SLAVE HOSTS. The minimal configuration for this is the report_host parameter, but there are other report parameters as well for the port, username, and password.

--recursion-method — type: string

Preferred recursion method used to find slaves.

Possible methods are:

METHOD       USES
===========  ================
processlist  SHOW PROCESSLIST
hosts        SHOW SLAVE HOSTS

The processlist method is preferred because SHOW SLAVE HOSTS is not reliable. However, the hosts method is required if the server uses a non-standard port (not 3306). Usually mk-slave-restart does the right thing and finds the slaves, but you may give a preferred method and it will be used first. If it doesn't find any slaves, the other methods will be tried.

--run-time — type: time

Time to run before exiting. Causes mk-slave-restart to stop after the specified time has elapsed. Optional suffix: s=seconds, m=minutes, h=hours, d=days; if no suffix, s is used.

--sentinel — type: string; default: /tmp/mk-slave-restart-sentinel

Exit if this file exists.

--set-vars — type: string; default: wait_timeout=10000

Set these MySQL variables. Immediately after connecting to MySQL, this string will be appended to SET and executed.

--skip-count — type: int; default: 1

Number of statements to skip when restarting the slave.

--sleep — type: int; default: 1

Initial sleep seconds between checking the slave.

See "SLEEP".

--socket — short form: -S; type: string

Socket file to use for connection.

--stop — Stop running instances by creating the sentinel file.

Causes mk-slave-restart to create the sentinel file specified by --sentinel. This should have the effect of stopping all running instances which are watching the same sentinel file. If --monitor isn't specified, mk-slave-restart will exit after creating the file. If it is specified, mk-slave-restart will wait the interval given by --max-sleep, then remove the file and continue working.

You might find this handy to stop cron jobs gracefully if necessary, or to replace one running instance with another. For example, if you want to stop and restart mk-slave-restart every hour (just to make sure that it is restarted every hour, in case of a server crash or some other problem), you could use a crontab line like this:

0 * * * * mk-slave-restart --monitor --stop --sentinel /tmp/mk-slave-restartup

The non-default --sentinel will make sure the hourly cron job stops only instances previously started with the same options (that is, from the same cron job).

🌈 DSN OPTIONS 🌈

These DSN options are used to create a DSN. Each option is given like option=value. The options are case-sensitive, so P and p are not the same option. There cannot be whitespace before or after the = and if the value contains whitespace it must be quoted. DSN options are comma-separated. See the maatkit manpage for full details. 📖

A — dsn: charset; copy: yes

Default character set.

D — dsn: database; copy: yes

Default database.

F — dsn: mysql_read_default_file; copy: yes

Only read default options from the given file

h — dsn: host; copy: yes

Connect to host.

p — dsn: password; copy: yes

Password to use when connecting.

P — dsn: port; copy: yes

Port number to use for connection.

S — dsn: mysql_socket; copy: yes

Socket file to use for connection.

u — dsn: user; copy: yes

User for login if not current user.

✨ DOWNLOADING ✨

okay so you want the goods? 💖 you can grab Maatkit straight from Google Code at <http://code.google.com/p/maatkit/>, or honestly just use a command like this and it's yours:

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

where toolname is, like, literally the name (or even just a fragment of a name) of any Maatkit tool you want. 🌸 once it's downloaded it's ready to run — no installation, no build step, no nothing. the first URL gets you the latest released version, and the second one gets you the latest trunk code from Subversion. iykyk 🦋

🌈 ENVIRONMENT 🌈

the environment variable MKDEBUG turns on verbose debugging output in all of the Maatkit tools, bestie:

MKDEBUG=1 mk-....

and here's the lil plot twist 👀 — when --daemonize is given and this variable is set, output gets directed to a debug file in /tmp.

🧚 SYSTEM REQUIREMENTS 🧚

you need Perl, DBI, DBD::mysql, and some core packages that ought to be installed in any reasonably new version of Perl. that's it. that's the list. 💅

💀 BUGS 💀

for a list of known bugs, go look here: <http://www.maatkit.org/bugs/mk-slave-restart>.

please use Google Code Issues and Groups to report bugs or request support: <http://code.google.com/p/maatkit/>. you can also join #maatkit on Freenode to discuss Maatkit — come hang out, it's a vibe. 🫶

and pLEASE, when you report something, include the complete command-line you used to reproduce the problem, the version of all MySQL servers involved, the complete output of the tool when run with --version, and if possible the debugging output from running with the MKDEBUG=1 environment variable. help us help you, fr fr 😭

👑 COPYRIGHT, LICENSE AND WARRANTY 👑

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

no cap, that's the whole warranty. there isn't one. 💀

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. go read them, they're iconic in a legal way 📜

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.

🔥 SEE ALSO 🔥

see also mk-table-checksum, mk-table-sync, mk-slave-delay. the whole squad, basically. ✨

🎀 AUTHOR 🎀

Baron Schwartz — the main character. 👑

⭐ ABOUT MAATKIT ⭐

this tool is part of Maatkit, a toolkit for power users of MySQL. Maatkit was created by Baron Schwartz; Baron and Daniel Nichter are the primary code contributors. both are employed by Percona. financial support for Maatkit development is primarily provided by Percona and its clients. 🌈

💜 VERSION 💜

this manual page documents Ver 1.0.22 Distrib 7540 $Revision: 7531 $.

okay that's the whole page, bestie, you made it to the end 🥹💅 this one documents mk-slave-restart(1) — Ver 1.0.22, Distrib 7540, $Revision: 7531 $ — and the page itself is dated 2025-07-24, rendered for perl v5.42.0. slay, go restart some slaves responsibly. 🎀✨🦋

📦 where this page comes from

fedora 43: maatkit 7540-39.fc43 · GPL-2.0-or-later OR Artistic-1.0-Perl
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on 2026-10-18: a language model's rewrite of the original, under its terms