|o||Read the tools documentation|
|o||Review the tools known BUGS|
|o||Test the tool on a non-production server|
|o||Backup your production server and verify the backups|
pt-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.
If you specify --verbose, pt-slave-restart prints a line every time it sees the slave has an error. See --verbose for details.
pt-slave-restart sleeps intelligently between polling the slave. The current sleep time varies.
o The initial sleep time is given by --sleep. o If it checks and finds an error, it halves the previous sleep time. o If it finds no error, it doubles the previous sleep time. o The sleep time is bounded below by --min-sleep and above by --max-sleep. o 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.
As of Percona Toolkit 2.2.8, pt-slave-restart supports Global Transaction IDs introduced in MySQL 5.6.5. Its important to keep in mind that:
o 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. o The default behavior is to skip the next transaction from the slaves master. Writes can originate on different servers, each with their own UUID.
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.
pt-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.
This tool accepts additional command-line arguments. Refer to the SYNOPSIS and usage information for details.
Show version and exit.
--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 Perls 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 doesnt 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.
--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 wont 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 doesnt find any slaves, the other methods will be tried.
--run-time type: time --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:
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 slaves master (Master_UUID from SHOW SLAVE STATUS) are skipped.
For example, with
master1 -> slave1 -> slave2
See GLOBAL TRANSACTION IDS.
--sleep type: int; default: 1
Initial sleep seconds between checking the slave.
--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 isnt 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 slaves relay logs instead. The coordinates are given by relay_log_file, relay_log_pos.
--user short form: -u; type: string --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
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 tools normal output. This feature should never interfere with the normal operation of the tool.
For more information, visit <https://www.percona.com/version-check>.
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.
dsn: charset; copy: yes
Default character set.
dsn: database; copy: yes
dsn: mysql_read_default_file; copy: yes
Only read default options from the given file
dsn: host; copy: yes
Connect to host.
dsn: password; copy: yes
Password to use when connecting.
dsn: port; copy: yes
Port number to use for connection.
dsn: mysql_socket; copy: yes
Socket file to use for connection.
dsn: user; copy: yes
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.
You need Perl, DBI, DBD::mysql, and some core packages that ought to be installed in any reasonably new version of Perl.
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:
If possible, include debugging output by running the tool with PTDEBUG; see ENVIRONMENT.
o Complete command-line used to run the tool o Tool --version o MySQL version of all servers involved o Output from the tool including STDERR o Input files (log/dump/config files, etc.)
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:
Replace TOOL with the name of any tool.
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.
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.
|perl v5.20.3||PT-SLAVE-RESTART (1)||2015-04-10|