Building Disaster Recovery Serviceguard Solutions Using Continentalclusters for Linux B.01.00.00

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
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.
rehearsal package The recovery cluster package used to validate the recovery environment and procedure as part
of a rehearsal operation.
remote failover Failover to a node at another data center or remote location.
resynchronization The process of making the data between two sites consistent and current once systems are restored
following a failure. Also called data resynchronization.
S
single system high
availability
Hardware design that results in a single system that has availability higher than normal. Hardware
design examples are:
• n+1 fans
• n+1 power supplies
• multiple power cords
• on-line addition or replacement of I/O cards, memory, and so on.
split-brain
syndrome
When a cluster reforms with equal numbers of nodes at every site, and every half of the cluster
acts as the authority and starts up the same set of applications, and tries to modify the same data,
resulting in data corruption. Serviceguard architecture prevents split-brain syndrome in all cases
unless dual cluster locks are used.
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.
SVOL A secondary volume configured in a P9000 and XP series disk array that uses Continuous Access.
SVOLs are the secondary copies in physical data replication with Continuos Access on the P9000
and XP.
synchronous data
replication
Each data replication I/O waits for the preceding I/O to complete before beginning another
replication. Minimizes the chance of inconsistent or corrupt data in the event of a rolling disaster.
T
transparent
failover
A client application that automatically reconnects to a new server without the user taking any
action.
transparent IP
failover
Moving the IP address from one network interface card (NIC), in the same node or another node,
to another NIC that is attached to the same IP subnet so that users or applications might always
specify the same IP name or address or both whenever they connect, even after a failure.
U-Z
volume group In LVM, a set of physical volumes such that logical volumes can be defined within the volume
group for user access. A volume group can be activated by only one node at a time unless you
are using Serviceguard OPS Edition. Serviceguard can activate a volume group when it starts a
package. A given disk can belong to only one volume group. A logical volume can belong to
only one volume group.
WAN data
replication
solutions
Data replication that functions over leased or switched lines. See also Continentalclusters.
86 Glossary