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

O
off-line data
replication.
Data replication by storing data off-line, usually a backup tape or disk stored in a safe location;
this method is best for applications that can accept a 24-hour recovery time.
on-line data
replication
Data replication by copying to another location that is immediately accessible. On-line data
replication is usually done by transmitting data over a link in real time or with a slight delay to
a remote site; this method is best for applications requiring quick recovery (within a few hours
or minutes).
P
cluster A cluster in production that has packages protected by the HP Continentalclusters product.
package alert Time at which a message is sent indicating a problem with a package.
package event A package condition such as a failure that causes a notification message to be sent. Package
events can be accompanied by alerts, but not alarms. Messages are for information only; the
cmrecovercl command is not enabled for a package event.
package recovery
group
A set of one or more packages with a mapping between their instances on the cluster and their
instances on the Recovery Cluster.
physical data
replication
An on-line data replication method that duplicates I/O writes to another disk on a physical block
basis. Physical replication can be hardware-based where data is replicated between disks over
a dedicated link (for example EMC’s Symmetrix Remote Data Facility or the HP StorageWorks E
Disk Array XP Series Continuous Access), or software-based where data is replicated on multiple
disks using dedicated software on the primary node (for example, MirrorDisk/UX).
planned downtime An anticipated period of time when nodes are taken down for hardware maintenance, software
maintenance (OS and application), backup, reorganization, upgrades (software or hardware),
etc.
PowerPath A host-based software product from Symmetrix that delivers intelligent I/O path management.
PowerPath is used for M by N Symmetrix configurations using Metrocluster with EMC SRDF.
primary package The package that normally runs on the cluster in a production environment.
pushbutton failover Use of the cmrecovercl command to allow all package recovery groups to start up on the
Recovery Cluster following a significant cluster event on the cluster.
PV links A method of LVM configuration that allows you to provide redundant disk interfaces and buses
to disk arrays, thereby protecting against single points of failure in disk cards and cables.
PVOL A primary volume configured in an P9000 or XP series disk array that uses Continuous Access.
PVOLs are the primary copies in physical data replication with Continuos Access on the P9000
or XP.
Q
quorum See See cluster quorum..
quorum server A cluster node that acts as a tie-breaker in a disaster tolerant architecture in case all of the nodes
in a data center go down at the same time. See also arbitrator.
R
R1 The Symmetrix term indicating the data copy that is the primary copy.
R2 The Symmetrix term indicating the remote data copy that is the secondary copy. It is normally
read-only by the nodes at the remote site.
RDF-ECA (RDF Enginuity Consistency Assist) A Solutions Enabler feature to provide consistency protection
for SRDF/Synchronous devices. RDF-ECA is used for M by N Symmetrix configurations using
Metrocluster with EMC SRDF.
Recovery Cluster A cluster on which recovery of a package takes place following a failure on the cluster.
recovery group
failover
A failover of a package recovery group from one cluster to another.
recovery package The package that takes over on the Recovery Cluster in the event of a failure on the cluster.
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