NOTE

Building an Extended Distance Cluster Using Serviceguard and Software RAID

Two Data Center and Quorum Service Location ArchitecturesTwo Data Center and Quorum Service Location Architectures

A two data center and Quorum Service location, which is at a third location, have the following configuration requirements:

There is no hard requirement on how far the Quorum Service location has to be from the two main data centers. It can be as close as the room next door with its own power source or can be as far as in another site across town. The distance between all three locations dictates that level of disaster tolerance a cluster can provide.

•In these solutions, there must be an equal number of nodes in each primary data center, and the third location (known as the arbitrator data center) contains the Quorum Server. LockLUN is not supported in a Disaster Tolerant configuration. In this release, only one node in each data center is supported.

•The Quorum Server is used as a tie-breaker to maintain cluster quorum when all communication between the two primary data centers is lost. The arbitrator data center must be located separately from the primary data centers. For more information about quorum server, see the Managing Serviceguard user’s guide and the Serviceguard Quorum Server Release Notes.

•A minimum of two heartbeat paths must be configured for all cluster nodes. The preferred solution is two separate heartbeat subnets configured in the cluster, each going over a separately routed network path to the other data center. Alternatively, there can be a single dedicated heartbeat subnet with a bonded pair configured for it. Each would go over a separately routed physical network path to the other data centers.

•There can be separate networking and Fibre Channel links between the data centers, or both networking and Fibre Channel can go over DWDM links between the data centers.

Chapter 2

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