/ 4.7. Configuring Resource Monitoring | ||||
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 | 4.6. Specifying Resource Failback Nodes (Resource Stickiness) | 4.8. Starting a New Cluster Resource |  | |
/ 4.7. Configuring Resource Monitoring | ||||
|---|---|---|---|---|
| 4.6. Specifying Resource Failback Nodes (Resource Stickiness) | 4.8. Starting a New Cluster Resource | | |
Although the High Availability Extension can detect a node failure, it also has the ability to detect when an individual resource on a node has failed. If you want to ensure that a resource is running, you must configure resource monitoring for that resource. Resource monitoring consists of specifying a timeout and/or start delay value, and an interval. The interval tells the CRM how often it should check the resource status.
Procedure 4.8. Adding or Modifying Monitor Operations
Start the Linux HA Management Client and log in to the cluster as described in Section 4.1, “Linux HA Management Client”.
In the Linux HA Management Client main window, click in the left pane to see the resources already configured for the cluster.
In the right pane, select the resource to modify and click . The next window shows the basic resource parameters and the meta attributes, instance attributes and operations already defined for that resource.
To add a new monitor operation, select the respective tab and click .
To modify an existing operation, select the respective entry and click .
Enter a unique for the monitor operation. When modifying existing monitor operations, the ID is already defined and is displayed in the configuration dialog.
In , select the action to perform, for example
monitor, start, or
.
In the field, enter a value in seconds.
In the field, enter a value in seconds.
After the specified timeout period, the operation will be treated as
failed. The PE will decide what to do or execute
what you specified in the field of the
monitor operation.
If needed, set optional parameters, like (what do if this action ever fails?) or (what conditions need to be satisfied before this action occurs?).
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If all parameters are set according to your wishes, click to finish the configuration of that resource. The configuration dialog is closed and the main window shows the modified resource.
If you do not configure resource monitoring, resource failures after a successful start will not be communicated, and the cluster will always show the resource as healthy.
If the resource monitor detects a failure, the following actions will take place:
Log file messages will be generated, according to the configuration
specified in the logging section of
/etc/ais/openais.conf (by default, written to
syslog, usually /var/log/messages).
The failure will be reflected in the Linux HA Management Client, the crm_mon tools, and in the CIB status section. To view them in the Linux HA Management Client, click in the left pane, then in the right pane, select the resource whose details you want to see.
The cluster will initiate noticeable recovery actions which may include stopping the resource to repair the failed state and restarting the resource locally or on another node. The resource also may not be restarted at all, depending on the configuration and state of the cluster.
