Ubuntu Manpage: mysqlrpladmin - Administration utility for MySQL replication

Provided by: mysql-utilities_1.3.5-2_all

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 operation 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 prerequisites. GTIDs are supported in version 5.6.5 and higher. This command
requires the options --master and either --slaves or --discover-slaves-login.

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. This command requires the
--slaves option. The --discover-slaves-login option is not allowed because, for failover,
the master is presumed to be offline or otherwise unreachable (so there is no way to
discover the slaves). The --master option is ignored for this command.

gtid This command is available to only those servers supporting GTIDs. It displays the
contents of the GTID variables, @@GLOBAL.GTID_EXECUTED, @@GLOBAL.GTID_PURGED, and
@@GLOBAL.GTID_OWNED. The command also displays universally unique identifiers (UUIDs) for
all servers. This command requires one of the following combinations: --master and
--slaves, or --master and --discover-slaves-login.

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. This command requires one of the following combinations:

• --master and --slaves;

• --master and --discover-slaves-login;

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. This command requires
the --slaves option. The --discover-slaves-login option is not allowed because it might
not provide the expected result, excluding slaves with the IO thread stopped. Optionally,
the --master option can also be used and in this case the utility will perform an
additional check to verify if the specified slaves are associated (i.e. replication
configured) to the given master.

start Execute the START SLAVE command on all slaves. This command requires the --slaves
option. The --discover-slaves-login option is not allowed because it might not provide the
expected result, excluding slaves with the IO thread stopped. Optionally, the --master
option can also be used and in this case the utility will perform an additional check to
verify if the specified slaves are associated (i.e. replication configured) to the given
master.

stop Execute the STOP SLAVE command on all slaves. This command requires the --slaves
option. The --discover-slaves-login option is not allowed because it might not provide the
expected result, excluding slaves with the IO thread stopped. Optionally, the --master
option can also be used and in this case the utility will perform an additional check to
verify if the specified slaves are associated (i.e. replication configured) to the given
master.

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. This command requires one of the following combinations:

• --master, --new-master and --slaves;

• --master, --new-master and --discover-slaves-login;

Detection of a downed master is performed as follows. If the connection to the master is
lost, wait --ping 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 following form (where the password,
port, and socket are optional).:

<*user*>[:<*passwd*>]@<*host*>[:<*port*>][:<*socket*>] or
<*login-path*>[:<*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 feature ignores any slaves it
cannot connect to or with the IO thread stopped (i.e. not connected to the master).

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 start, stop, and reset commands require the --slaves option to list all of the slaves
in the topology. Optionally, the --master option can be specified for the utility to check
if the specified slaves are associated to the given master before executing the command,
making sure that the command is only applied to slaves connected to the right replication
master.

The options required for the elect, 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 and connected to the
master.

The options required for switchover include the --master option to specify the existing
master, the --new-master option to specify the candidate slave (the slave to become the
new master), and either the --slaves option to list the considered 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 and connected to the master.

The failover command requires only the --slaves option to explicitly list all of the
slaves in the topology because it is expected that the master is down when this command is
used.

Use the --verbose option to see additional information in the health report and additional
messages during switchover or failover.
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>] or <login-path>[:<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=<slave_login>

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>] or
<login-path>. 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.

• --force

Ignore prerequisite checks or any inconsistencies found (e.g. errant transactions on
the slaves or SQL thread errors) forcing the execution of the specified command. This
option need to be used carefully as it will not solve any detected issue, but will
only ignore them displaying a warning message.

• --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 the format:
<user>[:<passwd>]@<host>[:<port>][:<socket>] or <login-path>[:<port>][:<socket>].

• --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>] or
<login-path>[:<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. This value is also used to
check down status of master. Failover will wait ping seconds to check master response.
If no response, failover event occurs.

• --quiet, -q

Turn off all messages for quiet execution.

• --rpl-user=<replication_user>

The user and password for the replication user requirement, in the format:
<user>[:<password>] or <login-path>. E.g. rpl:passwd Default = None.

• --script-threshold=<return_code>

Value for external scripts to trigger aborting the operation if result is greater than
or equal to the threshold.

Default = None (no threshold checking).

• --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>] or <login-path>[:<port>][:<socket>]. List
multiple slaves in comma-separated list. The list will be evaluated literally whereby
each server is considered a slave to the master listed regardless if they are a slave
of the master.

• --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 = 300 seconds.

• --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 appropriate servers as well as grant the
REPLICATE SLAVE privilege. The utility checks permissions for the master, slaves, and
candidates at startup.

Mixing IP and hostnames is not recommended. The replication-specific utilities will
attempt to compare hostnames and IP addresses as aliases for checking slave connectivity
to the master. However, if your installation does not support reverse name lookup, the
comparison could fail. Without the ability to do a reverse name lookup, the replication
utilities could report a false negative that the slave is (not) connected to the master.

For example, if you setup replication using MASTER_HOST=ubuntu.net on the slave and later
connect to the slave with mysqlrplcheck and have the master specified as
--master=192.168.0.6 using the valid IP address for ubuntu.net, you must have the ability
to do a reverse name lookup to compare the IP (192.168.0.6) and the hostname (ubuntu.net)
to determine if they are the same machine.

Similarly, if you use localhost to connect to the master, the health report may not show
all of the slaves. It is best to use the actual hostname of the master when connecting or
setting up replication.

If the user does not specify the --rpl-user and the user has specified the switchover or
failover command, the utility will check to see if the slaves are using
--master-info-repository=TABLE. If they are not, the utility will stop with an error.

All the commands require either the --slaves or --discover-slaves-login option but both
cannot be used at the same time. In fact, some commands only allow the use of the --slaves
option which is safer to specify the list slaves, because --discover-slaves-login might
not provide an up to date list of available slaves.

The path to the MySQL client tools should be included in the PATH environment variable in
order to use the authentication mechanism with login-paths. This will allow the utility to
use the my_print_defaults tools which is required to read the login-path values from the
login configuration file (.mylogin.cnf).
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 --slaves 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 master, 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 |
+------------+-------+---------+--------+------------+---------+

You can use the discover slaves feature, 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. Note that the option --discover-slaves-login cannot be used in
conjunction with the --slaves option.:

$ mysqlrpladmin --master=root@localhost:3332 --discover-slaves-login=root health
# Discovering slaves for master at localhost:3332
# Discovering slave at localhost:3331
# Found slave: localhost:3331
# Discovering slave at localhost:3333
# Found slave: localhost:3333
# Discovering slave at localhost:3334
# Found slave: localhost:3334
# Checking privileges.
#
# 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

AUTHOR

       Oracle Corporation (http://dev.mysql.com/).

NAME

SYNOPSIS

DESCRIPTION

COPYRIGHT

SEE ALSO

AUTHOR