Building a Disaster-proof Data Center with HP Serviceguard for Linux, June 2007

Figure 3. Extended distance cluster
In the previous configuration the network and Fibre Channel links between the data centers are
combined and sent over common DWDM links. Two DWDM links provide redundancy. When one of
them fails, the other can still be active and can keep the two data centers connected. Using the
DWDM link, clusters can now be extended to greater distances, which was not possible earlier due to
limits imposed by the Fibre Channel link for storage and Ethernet for networks. Storage in both data
centers is connected to both the nodes with two Fibre Channel switches in order to provide multiple
paths. This configuration supports a distance up to 100 km between data center 1 and data center 2.
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