Chapter 5 Monitoring ServiceGuard Package Dependencies

Halt the cluster. Include a force option to stop all packages, by typing:

cmhaltcl -f

To add an EMS resource, the ServiceGuard cluster must be down. You can modify existing EMS resources through ServiceGuard while the cluster is running.

From your command line, start SAM, by typing:

sam

Double-click the Clusters icon.

Double-click the High Availability Clusters icon.

Double-click on the Package Configuration icon.

The High Availability Clusters screen shows all requests currently configured on that system. If there are no requests currently configured, the field area is empty. Figure 5-1 “High Availability Clusters Screen” shows the High Availability Clusters screen with the Actions menu displayed.

Figure 5-1 High Availability Clusters Screen

From the Actions menu, select either the Create/Add a Package or Modify Package Configuration option.

If you select Create/Add a Package, a screen similar to Figure 5-2 “Create/Add a Package Screen”, displays.

Figure 5-2 Create/Add a Package Screen

If you have not previously done so, click Specify Package Name and Node and Specify Package SUBNET Address. Then click on Specify Package Resource Dependencies... to add EMS resources as package dependencies. A screen similar to Figure 5-3 “Package Resource Dependencies Screen” displays.

Figure 5-3 Package Resource Dependencies Screen

The Resources: field lists all the installed resources discovered by ServiceGuard. To make a package dependent on an EMS resource, select it from the list, then click Add Resource.... An Add Resources screen, similar to Figure 5-4 “Add Resources Screen” displays.

Figure 5-4 Add Resources Screen

Click through the Resource Classes and Resource Names to select the entity you wish to monitor. Click OK. A Resource Parameters screen, similar to Figure 5-5 “Resource Parameters Screen” displays.

The example in Figure 5-5 “Resource Parameters Screen” shows the possible values for pv_summary. Different resources show different available UP values.

Figure 5-5 Resource Parameters Screen

	NOTE: Make sure you always select UP in the Resources Up Values field. ServiceGuard creates an EMS request that sends an event if the Resources Up Value field is not equal to the UP value.

If you select only UP, the package fails over if the value is anything but UP. In this example, if you select UP and PVG-UP, the package fails over if the pv_summary value is not equal to UP or PVG_UP; in other words, if pv_summary is SUSPECT or DOWN.

The polling interval determines the maximum amount of elapsed time before the monitor knows about a change in resource status. For critical resources, you may want to set a short polling interval, such as 30 seconds, but this could adversely affect system performance. With longer polling intervals you gain system performance, but you risk not detecting problems soon enough.

You can also add resources as package dependencies by modifying the package configuration file. The default filename is /etc/cmcluster/pkg_name.ascii. See Managing MC/ServiceGuard for details on how to modify this file. For example, the syntax might be:

RESOURCE_NAME               /vg/vg01/pv_summary
RESOURCE_POLLING_INTERVAL   60
RESOURCE_UP_VALUE           = UP
RESOURCE_UP_VALUE           = PVG_UP    

ServiceGuard automatically distributes this information to every node in the cluster when the package configuration file is applied to the cluster configuration (see the cmapplyconf command).