MYSQLRPLADMIN(1) MySQL Utilities MYSQLRPLADMIN(1)
NAME
mysqlrpladmin - Administration utility for MySQL replication
SYNOPSIS
mysqlrpladmin [options]
DESCRIPTION
This utility permits users to perform administrative actions on a replication topology consisting of a master and its slaves. The utility
is designed to make it easy to recover from planned maintenance of the master or from an event that takes the master offline unexpectedly.
The act of taking the master offline intentionally and switching control to another slave is called switchover. In this case, there is no
loss of transactions as the master is locked and all slaves are allowed to catch up to the master. Once the slaves have read all events
from the master, the master is shutdown and control switched to a slave (in this case called a candidate slave).
Recovering from the loss of a downed master is more traumatic and since there is no way to know what transactions the master may have
failed to send, the new master (called a candidate slave) must be the slave that is most up-to-date. How this is determined depends on the
version of the server (see below). However, it can result in the loss of some transactions that were executed on the downed master but not
sent. The utility accepts a list of slaves to be considered the candidate slave. If no slave is found to meet the requirements, the opera-
tion will search the list of known slaves.
The utility also provides a number of useful commands for managing a replication topology including the following.
elect This command is available to only those servers supporting global transaction identifiers (GTIDs), perform best slave election and
report best slave to use in the event a switchover or failover is required. Best slave election is simply the first slave to meet the pre-
requisites. GTIDs are supported in version 5.6.5 and higher.
failover This command is available to only those servers supporting GTIDs. Conduct failover to the best slave. The command will test each
candidate slave listed for the prerequisites. Once a candidate slave is elected, it is made a slave of each of the other slaves thereby
collecting any transactions executed on other slaves but not the candidate. In this way, the candidate becomes the most up-to-date slave.
gtid This command is available to only those servers supporting GTIDs. It displays the contents of the GTID variables, @@GLOBAL.GTID_DONE,
@@GLOBAL.GTID_LOST, and @@GLOBAL.GTID_OWNED. The command also displays universally unique identifiers (UUIDs) for all servers.
health Display the replication health of the topology. By default, this includes the host name, port, role (MASTER or SLAVE) of the server,
state of the server (UP = is connected, WARN = not connected but can ping, DOWN = not connected and cannot ping), the GTID_MODE, and health
state.
The master health state is based on the following; if GTID_MODE=ON, the server must have binary log enabled, and there must exist a user
with the REPLICATE SLAVE privilege.
The slave health state is based on the following; the IO_THREAD and SQL_THREADS must be running, it must be connected to the master, there
are no errors, the slave delay for non-gtid enabled scenarios is not more than the threshold provided by the --max-position and the slave
is reading the correct master log file, and slave delay is not more than the --seconds-behind threshold option.
reset Execute the STOP SLAVE and RESET SLAVE commands on all slaves.
start Execute the START SLAVE command on all slaves.
stop Execute the STOP SLAVE command on all slaves.
switchover Perform slave promotion to a specified candidate slave as designated by the --new-master option. This command is available for
both gtid-enabled servers and non-gtid-enabled scenarios.
Detection of a downed master is performed as follows. If the connection to the master is lost, wait --timeout seconds and check again. If
the master connection is lost and the master cannot be pinged or reconnected, the failover event occurs.
For all commands that require specifying multiple servers, the options require a comma-separated list of connection parameters in the fol-
lowing form where the password, port, and socket are optional.:
<*user*>[:<*passwd*>]@<*host*>[:<*port*>][:<*socket*>],
The utility permits users to discover slaves connected to the master. In order to use the discover slaves feature, all slaves must use the
--report-host and --report-port startup variables to specify the correct hostname and ip port of the slave. If these are missing or report
the incorrect information, the slaves health may not be reported correctly or the slave may not be listed at all. The discover slaves fea-
ture ignores any slaves it cannot connect to.
The utility permits the user to demote a master to a slave during the switchover operation. The --demote-master option tells the utility
to, once the new master is established, make the old master a slave of the new master. This permits rotation of the master role among a set
of servers.
The utility permits the user to specify an external script to execute before and after the switchover and failover commands. The user can
specify these with the --exec-before and --exec-after options. The return code of the script is used to determine success thus each script
must report 0 (success) to be considered successful. If a script returns a value other than 0, the result code is presented in an error
message.
The utility permits the user to log all actions taken during the commands. The --log option requires a valid path and file name of the file
to use for logging operations. The log is active only when this option is specified. The option --log-age specifies the age in days that
log entries are kept. The default is seven (7) days. Older entries are automatically deleted from the log file (but only if the --log
option is specified).
The format of the log file includes the date and time of the event, the level of the event (informational - INFO, warning - WARN, error -
ERROR, critical failure - CRITICAL), and the message reported by the utility.
The utility has a number of options each explained in more detail below. Some of the options are specific to certain commands. Warning
messages are issued whenever an option is used that does not apply to the command requested. A brief overview of each command and its
options is presented in the following paragraphs.
The elect, failover, start, stop, and reset commands require either the --slaves option to list all of the slaves in the topology or the
--discover-slaves-login option to provide the user name and password to discover any slaves in the topology that are registered to the mas-
ter but are not listed in the --slaves option.
The options required for the health and gtid commands include the --master option to specify the existing master, and either the --slaves
option to list all of the slaves in the topology or the --discover-slaves-login option to provide the user name and password to discover
any slaves in the topology that are registered to the master but are not listed in the --slaves option.
Use the --verbose option to see additional information in the health report and additional messages during switchover or failover.
The options required for switchover include the --master option to specify the existing master, the --new-master option to specify the can-
didate slave (the slave to become the new master.
OPTIONS
mysqlrpladmin accepts the following command-line options:
--help Display a help message and exit.
--candidates=<candidate slave connections>
Connection information for candidate slave servers for failover in the form: <user>[:<passwd>]@<host>[:<port>][:<socket>]. Valid
only with failover command. List multiple slaves in comma- separated list.
--demote-master
Make master a slave after switchover.
--discover-slaves-login=<user:password>
At startup, query master for all registered slaves and use the user name and password specified to connect. Supply the user and
password in the form <user>[:<passwd>]. For example, --discover=joe:secret will use 'joe' as the user and 'secret' as the password
for each discovered slave.
--exec-after=<script>
Name of script to execute after failover or switchover. Script name may include the path.
--exec-before=<script>
Name of script to execute before failover or switchover. Script name may include the path.
--format=<format>, -f <format>
Display the replication health output in either grid (default), tab, csv, or vertical format.
--log=<log_file>
Specify a log file to use for logging messages
--log-age=<days>
Specify maximum age of log entries in days. Entries older than this will be purged on startup. Default = 7 days.
--master=<connection>
Connection information for the master server in <user>[:<passwd>]@<host>[:<port>][:<socket>] format.
--max-position=<position>
Used to detect slave delay. The maximum difference between the master's log position and the slave's reported read position of the
master. A value greater than this means the slave is too far behind the master. Default = 0.
--new-master=<connection>
Connection information for the slave to be used to replace the master for switchover in the form:
<user>[:<passwd>]@<host>[:<port>][:<socket>]. Valid only with switchover command.
--no-health
Turn off health report after switchover or failover.
--ping=<number>
Number of ping attempts for detecting downed server. Note: on some platforms this is the same as number of seconds to wait for ping
to return.
--quiet, -q
Turn off all messages for quiet execution.
--seconds-behind=<seconds>
Used to detect slave delay. The maximum number of seconds behind the master permitted before slave is considered behind the master.
Default = 0.
--slaves=<slave connections>
Connection information for slave servers in the form: <user>[:<passwd>]@<host>[:<port>][:<socket>]. List multiple slaves in
comma-separated list.
--timeout=<seconds>
Maximum timeout in seconds to wait for each replication command to complete. For example, timeout for slave waiting to catch up to
master. Default = 3. Also used to check down status of master. Failover will wait timeout seconds to check master response. If no
response, failover event occurs.
--verbose, -v
Specify how much information to display. Use this option multiple times to increase the amount of information. For example, -v =
verbose, -vv = more verbose, -vvv = debug.
--version
Display version information and exit.
NOTES
The login user must have the appropriate permissions to execute SHOW SLAVE STATUS, SHOW MASTER STATUS, and SHOW VARIABLES on the appropri-
ate servers as well as grant the REPLICATE SLAVE privilege. The utility checks permissions for the master, slaves, and candidates at
startup.
The --force option cannot be used with the failover command.
EXAMPLES
To perform best slave election for a topology with GTID_MODE=ON (server version 5.6.5 or higher) where all slaves are specified with the
--slaves1 option, run the following command.:
$ mysqlrpladmin --master=root@localhost:3331
--slaves=root@localhost:3332,root@localhost:3333,root@localhost:3334 elect
# Electing candidate slave from known slaves.
# Best slave found is located on localhost:3332.
# ...done.
To perform best slave election supplying a candidate list, use the following command.:
$ mysqlrpladmin --master=root@localhost:3331
--slaves=root@localhost:3332,root@localhost:3333,root@localhost:3334
--candidates=root@localhost:3333,root@localhost:3334 elect
# Electing candidate slave from candidate list then slaves list.
# Best slave found is located on localhost:3332.
# ...done.
To perform failover after a master has failed, use the following command.:
$ mysqlrpladmin
--slaves=root@localhost:3332,root@localhost:3333,root@localhost:3334
--candidates=root@localhost:3333,root@localhost:3334 failover
# Performing failover.
# Candidate slave localhost:3333 will become the new master.
# Preparing candidate for failover.
# Creating replication user if it does not exist.
# Stopping slaves.
# Performing STOP on all slaves.
# Switching slaves to new master.
# Starting slaves.
# Performing START on all slaves.
# Checking slaves for errors.
# Failover complete.
# ...done.
To see the replication health of a topology with GTID_MODE=ON (server version 5.6.5 or higher) and discover all slaves attached to the mas-
ter, run the following command. We use the result of the failover command above.:
$ mysqlrpladmin --master=root@localhost:3333
--slaves=root@localhost:3332,root@localhost:3334 health
# Getting health for master: localhost:3333.
#
# Replication Topology Health:
+------------+-------+---------+--------+------------+---------+
| host | port | role | state | gtid_mode | health |
+------------+-------+---------+--------+------------+---------+
| localhost | 3333 | MASTER | UP | ON | OK |
| localhost | 3332 | SLAVE | UP | ON | OK |
| localhost | 3334 | SLAVE | UP | ON | OK |
+------------+-------+---------+--------+------------+---------+
# ...done.
To view a detailed replication health report but with all of the replication health checks revealed, use the --verbose option as shown
below. In this example, we use vertical format to make viewing easier.:
$ mysqlrpladmin --master=root@localhost:3331
--slaves=root@localhost:3332,root@localhost:3333,root@localhost:3334
--verbose health
# Getting health for master: localhost:3331.
# Attempting to contact localhost ... Success
# Attempting to contact localhost ... Success
# Attempting to contact localhost ... Success
# Attempting to contact localhost ... Success
#
# Replication Topology Health:
************************* 1. row *************************
host: localhost
port: 3331
role: MASTER
state: UP
gtid_mode: ON
health: OK
version: 5.6.5-m8-debug-log
master_log_file: mysql-bin.000001
master_log_pos: 571
IO_Thread:
SQL_Thread:
Secs_Behind:
Remaining_Delay:
IO_Error_Num:
IO_Error:
************************* 2. row *************************
host: localhost
port: 3332
role: SLAVE
state: UP
gtid_mode: ON
health: OK
version: 5.6.5-m8-debug-log
master_log_file: mysql-bin.000001
master_log_pos: 571
IO_Thread: Yes
SQL_Thread: Yes
Secs_Behind: 0
Remaining_Delay: No
IO_Error_Num: 0
IO_Error:
************************* 3. row *************************
host: localhost
port: 3333
role: SLAVE
state: UP
gtid_mode: ON
health: OK
version: 5.6.5-m8-debug-log
master_log_file: mysql-bin.000001
master_log_pos: 571
IO_Thread: Yes
SQL_Thread: Yes
Secs_Behind: 0
Remaining_Delay: No
IO_Error_Num: 0
IO_Error:
************************* 4. row *************************
host: localhost
port: 3334
role: SLAVE
state: UP
gtid_mode: ON
health: OK
version: 5.6.5-m8-debug-log
master_log_file: mysql-bin.000001
master_log_pos: 571
IO_Thread: Yes
SQL_Thread: Yes
Secs_Behind: 0
Remaining_Delay: No
IO_Error_Num: 0
IO_Error:
4 rows.
# ...done.
To run the same failover command above, but specify a log file, use the following command.:
$ mysqlrpladmin
--slaves=root@localhost:3332,root@localhost:3333,root@localhost:3334
--candidates=root@localhost:3333,root@localhost:3334
--log=test_log.txt failover
# Performing failover.
# Candidate slave localhost:3333 will become the new master.
# Preparing candidate for failover.
# Creating replication user if it does not exist.
# Stopping slaves.
# Performing STOP on all slaves.
# Switching slaves to new master.
# Starting slaves.
# Performing START on all slaves.
# Checking slaves for errors.
# Failover complete.
# ...done.
After this command, the log file will contain entries like the following:
2012-03-19 14:44:17 PM INFO Executing failover command...
2012-03-19 14:44:17 PM INFO Performing failover.
2012-03-19 14:44:17 PM INFO Candidate slave localhost:3333 will become the new master.
2012-03-19 14:44:17 PM INFO Preparing candidate for failover.
2012-03-19 14:44:19 PM INFO Creating replication user if it does not exist.
2012-03-19 14:44:19 PM INFO Stopping slaves.
2012-03-19 14:44:19 PM INFO Performing STOP on all slaves.
2012-03-19 14:44:19 PM INFO Switching slaves to new master.
2012-03-19 14:44:20 PM INFO Starting slaves.
2012-03-19 14:44:20 PM INFO Performing START on all slaves.
2012-03-19 14:44:20 PM INFO Checking slaves for errors.
2012-03-19 14:44:21 PM INFO Failover complete.
2012-03-19 14:44:21 PM INFO ...done.
To perform switchover and demote the current master to a slave, use the following command.:
$ mysqlrpladmin --master=root@localhost:3331
--slaves=root@localhost:3332,root@localhost:3333,root@localhost:3334
--new-master=root@localhost:3332 --demote-master switchover
# Performing switchover from master at localhost:3331 to slave at localhost:3332.
# Checking candidate slave prerequisites.
# Waiting for slaves to catch up to old master.
# Stopping slaves.
# Performing STOP on all slaves.
# Demoting old master to be a slave to the new master.
# Switching slaves to new master.
# Starting all slaves.
# Performing START on all slaves.
# Checking slaves for errors.
# Switchover complete.
# ...done.
If the replication health report is generated on the topology following the above command, it will display the old master as a slave as
shown below.:
# Replication Topology Health:
+------------+-------+---------+--------+------------+---------+
| host | port | role | state | gtid_mode | health |
+------------+-------+---------+--------+------------+---------+
| localhost | 3332 | MASTER | UP | ON | OK |
| localhost | 3331 | SLAVE | UP | ON | OK |
| localhost | 3333 | SLAVE | UP | ON | OK |
| localhost | 3334 | SLAVE | UP | ON | OK |
+------------+-------+---------+--------+------------+---------+
To use the discover slaves feature, you can omit the --slaves option if and only if all slaves report their host and port to the master. A
sample command to generate a replication health report with discovery is shown below. he option:--discover-slaves-login option can be used
in conjunction with the --slaves option to specify a list of known slaves (or slaves that do not report their host and ip) and to discover
any other slaves connected to the master.:
$ mysqlrpladmin --master=root@localhost:3332
--discover-slaves-login=root health
# Discovering slaves for master at localhost:3332
# Getting health for master: localhost:3332.
#
# Replication Topology Health:
+------------+-------+---------+--------+------------+---------+
| host | port | role | state | gtid_mode | health |
+------------+-------+---------+--------+------------+---------+
| localhost | 3332 | MASTER | UP | ON | OK |
| localhost | 3331 | SLAVE | UP | ON | OK |
| localhost | 3333 | SLAVE | UP | ON | OK |
| localhost | 3334 | SLAVE | UP | ON | OK |
+------------+-------+---------+--------+------------+---------+
# ...done.
COPYRIGHT
Copyright (c) 2011, 2012, Oracle and/or its affiliates. All rights reserved.
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 of the License.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MER-
CHANTABILITY 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 this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
AUTHOR
MySQL Utilities Team
COPYRIGHT
2010, Oracle and/or its affiliates. All rights reserved.
1.0.3 May 09, 2012 MYSQLRPLADMIN(1)