Designing a Metropolitan Cluster
Designing a Disaster Tolerant Architecture for use with Metrocluster Products
Chapter 122
Designing a Disaster Tolerant Architecture
for use with Metrocluster Products
Metrocluster is designed for use in a metropolitan cluster or
metropolitan cluster environment within the 100 km distance limit.
All nodes must be members of a single Serviceguard cluster. Two
configurations are supported:
• A single data center without arbitrators (not disaster tolerant.)
• Two data centers and a third location architecture with one or two
arbitrator systems or a quorum server system. See Figure 1-1 on
page 23.
Following are the disaster tolerant architecture requirements:
• In the disaster tolerant cluster architecture, it is expected that each
data center is self-contained such that the loss of one data center
does not cause the entire cluster to fail. It is important that all single
points of failure (SPOF) be eliminated so that surviving systems
continue to run in the event that one or more systems fail.
• It is also expected that the networks between the data centers are
redundant and routed in such a way that the loss of any one data
center does not cause the network between surviving data centers to
fail.
• Exclusive volume group activation must be used for all Volume
Groups (VG) associated with packages that use the XP Series disk
array. The design of the Metrocluster Continuous Access script
assumes that only one system in the cluster will have a VG activated
at any time.
Single Data Center
A single data center architecture is supported, but it is not a true
disaster tolerant architecture. If the entire data center fails, there will be
no automated failover. This architecture is only valid for protecting data
through data replication, and for protecting against multiple node
failures.