high availability

A combination of technology, processes, and support partnerships that provide greater application

 

or system availability.

J, K, L

 

local cluster

A cluster located in a single data center. This type of cluster is not disaster tolerant.

local failover

Failover on the same node; this most often applied to hardware failover, for example local LAN

 

failover is switching to the secondary LAN card on the same node after the primary LAN card

 

has failed.

logical data

A type of on-line data replication that replicates logical transactions that change either the

replication

filesystem or the database. Complex transactions may result in the modification of many diverse

 

physical blocks on the disk.

LUN

(Logical Unit Number) A SCSI term that refers to a logical disk device composed of one or more

 

physical disk mechanisms, typically configured into a RAID level.

M

 

M by N

A type of Symmetrix grouping in which up to two Symmetrix frames may be configured on either

 

side of a data replication link in a Metrocluster with EMC SRDF configuration. M by N

 

configurations include 1 by 2, 2 by 1, and 2 by 2.

Maintenance mode

A recovery group is in the maintenance mode when it is disabled. The cmrecovercl

 

-dcommand moves a recovery group is moved into maintenance mode. The cmrecovercl -e

 

command moved the recovery group out of the maintenance mode. When a recovery group is

 

in the maintenance mode, recovery is not allowed.

manual failover

Failover requiring human intervention to start an application or service on another node.

Metrocluster

A Hewlett-Packard product that allows a customer to configure an Serviceguard cluster as a

 

disaster tolerant metropolitan cluster.

Metrocluster

Metrocluster uses a configuration file that includes variables that define the environment for the

Environment File

Metrocluster to operate in a Serviceguard cluster. This configuration file is referred to as the

 

Metrocluster environment file. This file needs to be available on all nodes in the cluster for

 

Metrocluster to function successfully.

metropolitan

A cluster that is geographically dispersed within the confines of a metropolitan area requiring

cluster

right-of-way to lay cable for redundant network and data replication components.

mirrored data

Data that is copied using mirroring.

mirroring

Disk mirroring hardware or software, such as MirrorDisk/UX. Some mirroring methods may allow

 

splitting and merging.

mission critical

Hardware, software, processes and support services that must meet the uptime requirements of

application

an organization. Examples of mission critical application that must be able to survive regional

 

disasters include financial trading services, e-business operations, 911 phone service, and patient

 

record databases.

mission critical

The architecture and processes that provide the required uptime for mission critical applications.

solution

 

multiple points of

More than one point of failure that can bring down an Serviceguard cluster.

failure (MPOF)

 

multiple system

Cluster technology and architecture that increases the level of availability by grouping systems

high availability

into a cooperative failover design.

mutual recovery

Continentalclusters configuration in which each cluster serves the roles of primary and recovery

configuration

cluster for different recovery groups. Also known as a bi-directional configuration.

N

 

network failover The ability to restore a network connection after a failure in network hardware when there are redundant network links to the same IP subnet.

notification

A message that is sent following a cluster or package event.

518 Glossary