3.2 KiB
NDB Cluster Monitor
Overview
The MySQL Cluster Monitor is a monitoring module for MaxScale that monitors a MySQL Cluster. It assigns a NDB status for the server if it is a part of a MySQL Cluster.
Configuration
A minimal configuration for a monitor requires a set of servers for monitoring and a username and a password to connect to these servers. The user requires the REPLICATION CLIENT privilege to successfully monitor the state of the servers.
[MySQL Cluster Monitor]
type=monitor
module=ndbclustermon
servers=server1,server2,server3
user=myuser
passwd=mypwd
Optional parameters for all monitors
Here are optional parameters that are common for all the monitors.
monitor_interval
This is the time the monitor waits between each cycle of monitoring. The default value of 10000 milliseconds (10 seconds) should be lowered if you want a faster response to changes in the server states. The value is defined in milliseconds and the smallest possible value is 100 milliseconds.
monitor_interval=2500
backend_connect_timeout
This parameter controls the timeout for connecting to a monitored server. It is in seconds and the minimum value is 1 second. The default value for this parameter is 3 seconds.
backend_connect_timeout=6
backend_write_timeout
This parameter controls the timeout for writing to a monitored server. It is in seconds and the minimum value is 1 second. The default value for this parameter is 2 seconds.
backend_write_timeout=4
backend_read_timeout
This parameter controls the timeout for reading from a monitored server. It is in seconds and the minimum value is 1 second. The default value for this parameter is 1 seconds.
backend_read_timeout=2
MySQL Cluster Monitor optional parameters
These are optional parameters specific to the MySQL Cluster Monitor.
script
This script will be executed when a server changes its state. The parameter should be an absolute path to the script or it should be in the executable path.
script=/home/user/script.sh
This script will be called with the following command line arguments.
<name of the script> --event=<event type> --initiator=<server whose state changed> --nodelist=<list of all servers>
events
A list of event names which cause the script to be executed. If this option is not defined, all events cause the script to be executed. The list must contain a comma separated list of event names.
events=master_down,slave_down
Script events
Here is a table of all possible event types and their descriptions that the MySQL Cluster monitor can be called with.
| Event Name | Description |
|---|---|
| master_down | A Master server has gone down |
| master_up | A Master server has come up |
| slave_down | A Slave server has gone down |
| slave_up | A Slave server has come up |
| server_down | A server with no assigned role has gone down |
| server_up | A server with no assigned role has come up |
| ndb_down | A MySQL Cluster node has gone down |
| ndb_up | A MySQL Cluster node has come up |
| lost_master | A server lost Master status |
| lost_slave | A server lost Slave status |
| lost_ndb | A MySQL Cluster node lost node membership |
| new_master | A new Master was detected |
| new_slave | A new Slave was detected |
| new_ndb | A new MySQL Cluster node was found |