PT-SLAVE-RESTART(1) User Contributed Perl Documentation PT-SLAVE-RESTART(1)NAMEpt-slave-restart - Watch and restart MySQL replication after errors.
SYNOPSIS
Usage: pt-slave-restart [OPTIONS] [DSN]
pt-slave-restart watches one or more MySQL replication slaves for
errors, and tries to restart replication if it stops.
RISKS
Percona Toolkit is mature, proven in the real world, and well tested,
but all database tools can pose a risk to the system and the database
server. Before using this tool, please:
· Read the tool's documentation
· Review the tool's known "BUGS"
· Test the tool on a non-production server
· Backup your production server and verify the backups
DESCRIPTIONpt-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.
Although this tool can help a slave advance past errors, you should not
rely on it to "fix" replication. If slave errors occur frequently or
unexpectedly, you should identify and fix the root cause.
OUTPUT
If you specify "--verbose", pt-slave-restart prints a line every time
it sees the slave has an error. See "--verbose" for details.
SLEEPpt-slave-restart sleeps intelligently between polling the slave. The
current sleep time varies.
· 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, pt-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.
GLOBAL TRANSACTION IDS
As of Percona Toolkit 2.2.8, pt-slave-restart supports Global
Transaction IDs introduced in MySQL 5.6.5. It's important to keep in
mind that:
· pt-slave-restart will not skip transactions when multiple
replication threads are being used (slave_parallel_workers > 0).
pt-slave-restart does not know what the GTID event is of the failed
transaction of a specific slave thread.
· The default behavior is to skip the next transaction from the
slave's master. Writes can originate on different servers, each
with their own UUID.
See "--master-uuid".
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.
COMPATIBILITYpt-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.
OPTIONS
This tool accepts additional command-line arguments. Refer to the
"SYNOPSIS" and usage information for details.
--always
Start slaves even when there is no error. With this option
enabled, pt-slave-restart will not let you stop the slave manually
if you want to!
--ask-pass
Prompt for a password when connecting to MySQL.
--charset
short form: -A; type: string
Default character set. 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.
--[no]check-relay-log
default: yes
Check the last relay log file and position before checking for
slave errors.
By default pt-slave-restart will not doing 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
(i.e. restarting the same error in the same relay log file at the
same relay log position).
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.
--error-numbers
type: hash
Only restart this comma-separated list of errors. Makes pt-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, pt-slave-restart will try to
restart the slave. If it exists but doesn't match, pt-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 pt-slave-restart will sleep before polling the
slave again. This is also the time that pt-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 pt-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. The tool won't start if the PID file
already exists and the PID it contains is different than the
current PID. However, if the PID file exists and the PID it
contains is no longer running, the tool will overwrite the PID file
with the current PID. The PID file is removed automatically when
the tool 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."
pt-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, "pt-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: array; default: processlist,hosts
Preferred recursion method used to find slaves.
Possible methods are:
METHOD USES
=========== ==================
processlist SHOW PROCESSLIST
hosts SHOW SLAVE HOSTS
none Do not find slaves
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 pt-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 pt-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/pt-slave-restart-sentinel
Exit if this file exists.
--set-vars
type: Array
Set the MySQL variables in this comma-separated list of
"variable=value" pairs.
By default, the tool sets:
wait_timeout=10000
Variables specified on the command line override these defaults.
For example, specifying "--set-vars wait_timeout=500" overrides the
defaultvalue of 10000.
The tool prints a warning and continues if a variable cannot be
set.
--skip-count
type: int; default: 1
Number of statements to skip when restarting the slave.
--master-uuid
type: string
When using GTID, an empty transaction should be created in order to
skip it. If writes are coming from different nodes in the
replication tree above, it is not possible to know which event from
which UUID to skip.
By default, transactions from the slave's master ('Master_UUID'
from "SHOW SLAVE STATUS") are skipped.
For example, with
master1 -> slave1 -> slave2
When skipping events on slave2 that were written to master1, you
must specify the UUID of master1, else the tool will use the UUID
of slave1 by default.
See "GLOBAL TRANSACTION IDS".
--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 "pt-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, "pt-slave-restart" will exit after
creating the file. If it is specified, "pt-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 "pt-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 * * * * pt-slave-restart--monitor --stop --sentinel /tmp/pt-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).
See also "--sentinel".
--until-master
type: string
Run until this master log file and position. Start the slave, and
retry if it fails, until it reaches the given replication
coordinates. The coordinates are the logfile and position on the
master, given by relay_master_log_file, exec_master_log_pos. The
argument must be in the format "file,pos". Separate the filename
and position with a single comma and no space.
This will also cause an UNTIL clause to be given to START SLAVE.
After reaching this point, the slave should be stopped and pt-
slave-restart will exit.
--until-relay
type: string
Run until this relay log file and position. Like "--until-master",
but in the slave's relay logs instead. The coordinates are given
by relay_log_file, relay_log_pos.
--user
short form: -u; type: string
User for login if not current user.
--verbose
short form: -v; cumulative: yes; default: 1
Be verbose; can specify multiple times. Verbosity 1 outputs
connection information, a timestamp, relay_log_file, relay_log_pos,
and last_errno. Verbosity 2 adds last_error. See also
"--error-length". Verbosity 3 prints the current sleep time each
time pt-slave-restart sleeps.
--version
Show version and exit.
--[no]version-check
default: yes
Check for the latest version of Percona Toolkit, MySQL, and other
programs.
This is a standard "check for updates automatically" feature, with
two additional features. First, the tool checks the version of
other programs on the local system in addition to its own version.
For example, it checks the version of every MySQL server it
connects to, Perl, and the Perl module DBD::mysql. Second, it
checks for and warns about versions with known problems. For
example, MySQL 5.5.25 had a critical bug and was re-released as
5.5.25a.
Any updates or known problems are printed to STDOUT before the
tool's normal output. This feature should never interfere with the
normal operation of the tool.
For more information, visit
<https://www.percona.com/version-check>.
Show version and exit.
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 percona-toolkit 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.
ENVIRONMENT
The environment variable "PTDEBUG" enables verbose debugging output to
STDERR. To enable debugging and capture all output to a file, run the
tool like:
PTDEBUG=1 pt-slave-restart ... > FILE 2>&1
Be careful: debugging output is voluminous and can generate several
megabytes of output.
SYSTEM REQUIREMENTS
You need Perl, DBI, DBD::mysql, and some core packages that ought to be
installed in any reasonably new version of Perl.
BUGS
For a list of known bugs, see
<http://www.percona.com/bugs/pt-slave-restart>.
Please report bugs at <https://bugs.launchpad.net/percona-toolkit>.
Include the following information in your bug report:
· Complete command-line used to run the tool
· Tool "--version"
· MySQL version of all servers involved
· Output from the tool including STDERR
· Input files (log/dump/config files, etc.)
If possible, include debugging output by running the tool with
"PTDEBUG"; see "ENVIRONMENT".
DOWNLOADING
Visit <http://www.percona.com/software/percona-toolkit/> to download
the latest release of Percona Toolkit. Or, get the latest release from
the command line:
wget percona.com/get/percona-toolkit.tar.gz
wget percona.com/get/percona-toolkit.rpm
wget percona.com/get/percona-toolkit.deb
You can also get individual tools from the latest release:
wget percona.com/get/TOOL
Replace "TOOL" with the name of any tool.
AUTHORS
Baron Schwartz
ABOUT PERCONA TOOLKIT
This tool is part of Percona Toolkit, a collection of advanced command-
line tools for MySQL developed by Percona. Percona Toolkit was forked
from two projects in June, 2011: Maatkit and Aspersa. Those projects
were created by Baron Schwartz and primarily developed by him and
Daniel Nichter. Visit <http://www.percona.com/software/> to learn
about other free, open-source software from Percona.
COPYRIGHT, LICENSE, AND WARRANTY
This program is copyright 2011-2015 Percona LLC and/or its affiliates,
2007-2011 Baron Schwartz.
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.
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.
VERSIONpt-slave-restart 2.2.14
perl v5.20.2 2015-04-10 PT-SLAVE-RESTART(1)
