In
an MC/ServiceGuard
cluster configuration, high availability is achieved by using redundant
hardware to eliminate single points of failure. This protects the
cluster against hardware faults, such as the node failure in Figure 1-1 “High Availability Architecture. ”.
For some installations, this level of protection 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 impact. For these types of installations, and many more
like them, it is important to guard not only against single points
of failure, but 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 you with the ability to fail over automatically to another
part of the cluster or manually to a different 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.
Printable version
