Designing Disaster Recovery Clusters using Metroclusters and Continentalclusters, Reprinted October 2011 (5900-1881)

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
replication
A type of on-line data replication that replicates logical transactions that change either the
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
Environment File
Metrocluster uses a configuration file that includes variables that define the environment for the
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
cluster
A cluster that is geographically dispersed within the confines of a metropolitan area requiring
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
application
Hardware, software, processes and support services that must meet the uptime requirements of
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
solution
The architecture and processes that provide the required uptime for mission critical applications.
multiple points of
failure (MPOF)
More than one point of failure that can bring down an Serviceguard cluster.
multiple system
high availability
Cluster technology and architecture that increases the level of availability by grouping systems
into a cooperative failover design.
mutual recovery
configuration
Continentalclusters configuration in which each cluster serves the roles of primary and recovery
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