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| Oracle Solaris Cluster Data Service for MySQL Guide Oracle Solaris Cluster 4.1

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## Understanding the HA for MySQL Fault Monitor

This section describes the HA for MySQL fault monitor's probing algorithm or functionality, states the conditions, messages, and recovery actions associated with unsuccessful probing.

For conceptual information on fault monitors, see Data Services Fault Monitors in Oracle Solaris Cluster Concepts Guide.

### Resource Properties

The HA for MySQL fault monitor uses the same resource properties as resource type `SUNW.gds`. Refer to the `SUNW.gds`(5) man page for a complete list of resource properties used.

### Probing Algorithm and Functionality

- MySQL probing steps.

  - Sleeps for `Thorough_probe_interval`.

  - Tries to connect to the MySQL instance, with `mysqladmin` command with argument ping, with the defined fault-monitor user fault fmuser. If this fails, then the probe will restart the MySQL resource.

  - Every 300 seconds the probe will also check the following:

    - If the MySQL instance is a slave configuration, the probe will check whether the MySQL instance is connected to its master. If the Slave is not connected, the probe will write an error message to syslog.

    - Verify that the probe can list all databases and tables, not the contents. If the probe receives any errors the probe will write an error message to syslog.

    - Conduct an function test on the defined test-database, Create Table, Insert into Table, Update Table, Delete from Table and Drop Table. If any of those operations fails, then the probe will restart the MySQL resource.

  - If all MySQL processes have died, `pmf` will interrupt the probe to immediately restart the MySQL resource.

  - If the MySQL resource is repeatedly restarted and subsequently exhausts the `Retry_count` within the `Retry_interval` then a failover is initiated for the Resource Group onto another node if `Failover_enabled` is set to TRUE.

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