Understanding and Designing Serviceguard Disaster Recovery Architectures

Figure 27 Extended Distance Cluster Configuration with Two Data Centers and a Third Location
with DWDM Links
Node A Node B
DWDM
DWDM
Primary Data Center 1
Storage Storage
Primary Data Center 2
Node C Node D
Storage
DWDM
DWDM
Arbitrator Third location
Node E Node F
Maximum Distance
100 kilometers
Maximum Distance
100 kilometers
Redundant DWDM
Maximum distance
100 kilometers
Network
Switch
Network
Switch
DWDM DWDM
Network Switch Network Switch Network Switch Network Switch
FC Switch
FC Switch
FC Switch
FC Switch
In the this example, Figure 27 (page 65), the DWDM boxes connected between the two Primary
Data Centers are configured with redundant dark fiber links and the standby fiber feature is enabled.
The Arbitrator Data center can be up to 100 kilometers away from either Primary Data Center, if
DWDM links are used. It is also supported to connect to the Arbitrator data center without DWDM
links, as long as the distance is within the allowed specifications for the network type being used.
Cluster lock disks are not allowed in this configuration. The nodes in the Arbitrator data center can
either be members of the cluster, or a node might be running the Serviceguard Quorum Server.
There can be up to 16 nodes in this cluster (this includes the nodes in the Arbitrator data center,
unless they are running the Serviceguard Quorum Server).
Extended Distance Cluster configurations with Two Data Centers and a Third Location 65