The ScaleOut GeoServer® option extends distributed caching across multiple, geographically distributed data centers. This feature replicates stored objects between ScaleOut stores running on server farms at different sites.
GeoServer offers two approaches to replicating a cache's objects between different geographic locations. Two replication modes, Push and Pull, are available, depending on the product license in use:
|Licensed Option||Push Replication||Pull Replication|
|ScaleOut GeoServer® DR||Available||Unavailable|
|ScaleOut GeoServer® Pro||Available||Available|
Push replication asynchronously pushes changes across WAN links as soon as objects are updated. For example, a datacenter in New York City can continuously push its updates to Los Angeles, allowing the L.A. site to remain synchronized with NYC. Push replication is intended for disaster recovery, ensuring that stored objects are held at multiple geographic sites in case one of the sites becomes unavailable.
The pull replication model allows a site to pull objects from a remote datacenter as they are needed. Pull-based replication allows objects to be shared by a geographically diverse network of ScaleOut datagrids, where you define policies to control how frequently remote datacenters should update their local copies of the object. Furthermore, the authoritative "primary" copy of an object can migrate from datacenter to datacenter as needed. This model enables multiple sites to be combined into a single, "virtual" distributed data grid spanning multiple sites, providing global access to stored objects.
Version 5.10 of ScaleOut GeoServer® Pro enhances the pull replication mode when replicating between two ScaleOut StateServer stores, combining pull access with push replication. This replication model ensures that two copies of each object are always maintained, one in each store, while giving applications a single, coherent view of the object's data. ScaleOut GeoServer Pro automatically handles WAN outages to ensure uninterrupted operations. (See the User Guide for more information.)