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WAN clustering, also called geoclustering, high-availability clustering or remote clustering, is the use of multiple redundant computing resources located in different geographical locations to form what appears to be a single highly-available system.
The goal of WAN clustering is to support enterprise business continuity by providing location-independent load balancing and failover. WAN clustering can be used for just about any computing resource, including mainframes, file servers and software application stacks.
The biggest challenge in WAN clustering is to make sure that system states and their associated data are concurrent at multiple locations. Two advancements have helped administrators meet this challenge -- faster wide area network (WAN connection speeds and the ability to create and manage a clustered resource through a single virtualized master identity.