Understanding and Designing Serviceguard Disaster Recovery Architectures

disaster recovery
architecture
A cluster architecture that protects against multiple points of failure or a single catastrophic failure
that affects many components by locating parts of the cluster at a remote site and by providing
data replication to the remote site. Other components of disaster recovery architecture include
redundant links, either for networking or data replication, that are installed along different routes,
and automation of most or all of the recovery process.
disaster recovery
services
Services and products offered by companies that provide the hardware, software, processes,
and people necessary to recover from a disaster.
disaster tolerant The characteristic of being able to recover quickly from a disaster. Components of disaster recovery
include redundant hardware, data replication, geographic dispersion, partial or complete recovery
automation, and well-defined recovery procedures.
E, F
ESCON Enterprise Storage Connect. A type of fiber-optic channel used for inter-frame communication
between EMC Symmetrix frames using EMC SRDF or between HP Storage XP series disk array
units using Continuous Access XP.
event log The default location (/var/adm/cmconcl/eventlog) where events are logged on the monitoring
Continentalclusters system. All events are written to this log, and all notifications that are sent
elsewhere.
Extended Distance
Cluster
A cluster with alternate nodes located in different data centers separated by some distance.
Formerly known as campus cluster.
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.
filesystem
replication
The process of replicating filesystem changes from one node to another.
G
Groups Logical volume groups.
H, I
heartbeat network A network that provides reliable communication among nodes in a cluster, including the
transmission of heartbeat messages, signals from each functioning node, which are central to the
operation of the cluster, and which determine the health of the nodes in the cluster.
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 online 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.
76 Glossary