|Developing with Pivotal GemFire / Region Data Storage and Distribution|
Understand the difference between members that store data for a region and members that only act as data accessors to the region.
In most cases, when you define a data region in a member’s cache, you also specify whether the member is a data store. Members that store data for a region are referred to as data stores or data hosts. Members that do not store data are referred to as accessor members, or empty members. Any member, store or accessor, that defines a region can access it, put data into it, and receive events from other members. To configure a region so the member is a data accessor, you use configurations that specify no local data storage for the region. Otherwise, the member is a data store for the region.