Administration Guide

Introducing Event Management

Event Management is a distributed subsystem of the RS/6000 Cluster Technology (RSCT) software that can run on any |IBM pSeries or RS/6000 system. The RSCT software provides a set of high availability services to the PSSP software. The other services in the RSCT software are the Group Services and Topology Services (heartbeat) distributed subsystems. These three distributed subsystems operate within a domain. A domain is a set of |IBM pSeries or RS/6000 nodes where the RSCT components execute and, exclusively of other nodes, provide their services. On the SP system, a domain is an SP system partition. Note that a node may be in more than one RSCT domain; the control workstation is a member of each system partition and, therefore, a member of each RSCT domain. When a node is a member of more than one domain, there is an executing copy of each RSCT component for each domain.

The function of the Event Management subsystem is to match information about the state of system resources with information about resource conditions that are of interest to client programs, which can include applications, subsystems, and other programs. In this chapter, these client programs are referred to as EM clients.

Resource states are represented by resource variables. Resource conditions are represented as expressions that have a syntax that is a subset of the expression syntax of the C programming language.

Resource monitors are programs that observe the state of specific system resources and transform this state into several resource variables. The resource monitors periodically pass these variables to the Event Manager daemon. The Event Manager daemon applies expressions, which have been specified by EM clients, to each resource variable. If the expression is true, an event is generated and sent to the appropriate EM client. EM clients may also query the Event Manager daemon for the current values of resource variables.

Resource variables, resource monitors, and other related information are specified in several System Data Repository (SDR) object classes. Information stored in these SDR classes is then translated into a form that can be easily used by the Event Management subsystem.

For more conceptual information about the Event Management subsystem, or to learn how to use the Event Management Perspective to view descriptions of resource variables, see the RS/6000 Cluster Technology Event Management Programming Guide and Reference.