Building Disaster Recovery Serviceguard Solutions Using Metrocluster with 3PAR Remote Copy

redundant links, either for networking or data replication, that are installed along different routes,
and automation of most or all of the recovery process.
E-L
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.
failback Failing back from a backup node, which may or may not be remote, to the primary node that
the application normally runs on.
failover The transfer of control of an application or service from one node to another node after a failure.
Failover can be manual, requiring human intervention, or automated, requiring little or no human
intervention.
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.
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, N
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.
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.
notification A message that is sent following a cluster or package event.
O, P
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, the HP StorageWorks E
Disk Array XP Series Continuous Access, 3PAR Remote Copy and EVA Continuous Access), or
software-based where data is replicated on multiple disks using dedicated software on the primary
node (For Example, MirrorDisk/UX).
Q
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, S
Recovery Cluster A cluster on which recovery of a package takes place following a failure on the cluster.
recovery package The package that takes over on the Recovery Cluster in the event of a failure on the cluster.
resynchronization The process of making the data between two sites consistent and current once systems are restored
following a failure. Also called data resynchronization.
rolling disaster A second disaster that occurs before recovering from a previous disaster, For Example, while
data is being synchronized between two data centers after a disaster, one of the data centers
fails, interrupting the data synchronization process. Rolling disasters may result in data corruption
that requires a reload from tape backups.
sub-clusters Sub-clusters are clusterwares that run above the Serviceguard cluster and comprise only the nodes
in a Metrocluster site. Sub-clusters have access only to the storage arrays within a site.
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