HP HA s Software manual Configuring MC/ServiceGuard Package Dependencies, Service EMS

Installing and Using EMS

Using EMS HA Monitors

Configuring MC/ServiceGuard Package

Dependencies

This section describes how to use SAM to create package dependencies on EMS resources. This creates an EMS request to monitor that resource and to notify MC/ServiceGuard when that resource reaches a critical user-defined level. MC/ServiceGuard will then failover the package. Here are some examples of how EMS might be used:

• In a cluster where one copy of data is shared between all nodes in a cluster, you may want to fail over a package if the host adapter has failed on the node running the package. Because busses, controllers, and disks are shared, package fail over to another node because of bus, controller, or disk failure would not successfully run the package. To make sure you have proper failover in a shared data environment, you must create identical package dependencies on all nodes in the cluster. MC/ServiceGuard can then compare the resource “UP” values on all nodes and fail over to the node that has the correct resources available.

• In a cluster where each node has its own copy of data, you may want to fail over

	a package to another node for any number of reasons:
	• host adapter, bus, controller, or disk failure
	• unprotected data (the number of copies is reduced to one)
	• performance has degraded because one of the PV links has failed
	In this sort of cluster of web servers, where each node has a copy of the data and
	users are distributed for load balancing, you can fail over a package to another
	node with the correct resources available. Again, the package resource
	dependencies should be configured the same on all nodes.
	This information for creating requests is also valid for EMS monitors sold with
	other products (ATM or OTS, for example) and for user-written monitors written
	according to developer specifications in Writing Monitors for the Event Monitoring
	Service (EMS).
NOTE	You should create the same requests on all nodes in an MC/ServiceGuard cluster.
	A package can depend on any resource monitored by an EMS monitor. To create
	package dependencies, choose create or modify a package from the Package
	Configuration interface under the High Availability Clusters subarea of SAM,
	Figure 1-7. You see a new option called “Specify Package Resource Dependencies.”

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