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

Figure 1. High availability architecture
This architecture, which is typically implemented on one site in a single data center, is sometimes
called a local cluster. For some installations, the level of protection given by a local cluster is
insufficient. Consider the order-processing center where power outages are common during harsh
weather. Or, consider the systems running the stock market, where multiple system failures, for any
reason, have a significant financial important to guard not only against single points of failure, but
also against multiple points of failure (MPOF) or against single massive failures that cause many
components to fail, such as the failure of a data center, of an entire site, or of a small area. A data
center, in the context of disaster recovery, is a physically proximate collection of nodes and disks,
usually all in one room.
Creating clusters that are resistant to multiple points of failure or single massive failures requires a
different type of cluster architecture called a disaster tolerant architecture. This architecture provides
the ability to fail over automatically to another part of the cluster after certain disasters. Specifically,
the disaster tolerant cluster provides appropriate failover in the case where a disaster causes an entire
data center to fail, as illustrated in Figure 2.
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