Glossary

An event. A message sent to tell a user or application when that certain conditions are met, an action or state you want to know about. For example, you may want to be alerted when a disk fails or when available filesystem space falls below a certain level.

A monitor that monitors resource instances (or resource class) asynchronously. It is event driven and send notifications when events occur. It does not keep track of the current state or value of each resource it monitors.

The application that creates or cancels requests to monitor particular resources. The consumer of a resource status message. A user of the Resource Monitor framework. This user may browse resources, request status, and make requests to have resources monitored. Examples are MC/ServiceGuard as it starts a package or the SAM interface to EMS.

See Resource Dictionary.

The interface between the registrar, client applications, target applications, and resource monitors.

A set of APIs together with the registrar process and the resource dictionary, which allows client applications to request that resources be monitored and a target application be notified.

The SAM interface to EMS. One type of a client application, use it to create monitoring requests.

An alert.

A means to create requests, monitor, and report events about resources on a system. EMS observes a system and does not modify it.

High Availability.

HP OpenView IT/Operations, formerly known as Operations Center

The basic allocation unit for a logical volume is called a logical extent. For mirrored logical volumes, either two or three physical extents are mapped for each logical extent, depending on whether you are using 2-way or 3-way mirroring.

The segments of spaces that can be separated physically on a disk or be on serial disks. Each collection appears to the operating system as a single disk. Like disks, logical volumes can be used to hold file systems, raw data areas, dump areas, or swap areas. Unlike disks, logical volumes can be given a size when they are created, and a logical volume can later be expanded or reduced. Also, logical volumes can be spread over multiple disks.

(Logical Unit Numbers) A logical disk device composed of one or more physical disk mechanisms, typically configured into a RAID level.

(Logical Volume Manager) Software that manages disks in volume groups, and allows you to create logical and physical volume groupings.

(Management Information Base). A document that describes objects to be managed. A MIB is created using a grammar defined in "Structure of Management Information" (SMI) format. This grammar concisely defines the objects being managed, the data types these objects take, descriptions of how the objects can be used, whether the objects are read-only or read-write, and assigns identifiers for the objects.

An MIB that defines information about the system, the network interface cards, routing information, the TCP and UDP sockets and their states, and various statistics related to error counts. This MIB is widely adopted and is served by most IP-addressed devices. Most system and network resources managed by EMS HA Monitors are taken from this MIB.

See resource monitor.

See alert.

LVM divides each physical disk into addressed units called physical extents.

A disk that has been initialized by LVM.

The process by which a monitor obtains the most recent status of a resource. The method is defined by the monitor when it is created.

Determines the maximum amount of elapsed time before the monitor knows about a change in resource status.

The method used to send notification messages. The options through EMS include: opcmsg, SNMP, TCP, UDP, syslog, console, textlog and email.

A method of LVM configuration that allows you to provide redundant SCSI interfaces and buses to disk arrays, thereby protecting against single points of failure in SCSI cards and cables.

A grouping of physical devices (host adapters, busses, controllers, or disks), that allow LVM to manage redundant links or mirrored disks and access the redundant hardware when the primary hardware fails.

Software that provides the link between clients (resource status consumers) and resource monitors (resource status providers). The central part of the resource monitor framework which uses the resource dictionary to act as an intermediary between client systems and resource monitors.

Any entity that a monitor application developer names. Examples include a network interface, CPU statistics, a MIB object, and a network service.

A group of EMS resources organized into a filesystem type structure. Examples include system resources and cluster resources. See resource instance.

A set of files that provide to the registrar a hierarchy of resources on the local system and respective resource monitors.

The actual resources that can be monitored. For example, /net/interfaces/lan/status/lan0 may refer to a particular network interface installed on the monitored system. See resource class.

The process that is used to obtain the status of a resource and send event notifications if appropriate. A monitor checks resources on the local system. The resource monitor maps the physical resource into a standard interface understood by EMS.

A full resource path includes the resource class hierarchy and instance.

(Simple Network Management Protocol) Standard protocol for network-based retrieval of information about system resources.

The current value of a resource (UP or DOWN). For some resource instances, a monitor may need to maintain a history of past events or conditions in order to know the resource value. In this case, a monitor is said to be maintaining state information. Stateless monitors do not keep any history of past conditions.

The target application is notified when a monitored resource reaches the condition for which notification was requested. For example, a target application could be MC/ServiceGuard or IT/Operations (ITO).

In LVM, a set of physical volumes whose extents are grouped together and then made available to users as logical volumes. A volume group can be activated by only one node at a time unless you are using MC/LockManager. MC/ServiceGuard can activate a volume group when it starts a package. A given disk can belong to only one volume group. A logical volume can belong to only one volume group.