|Getting Started with GemFire XD / Understanding the GemFire XD Distributed System|
Member processes form a single, logical system, and each member has single-hop access to any other member, with single-hop or no-hop access to data.
A GemFire XD member is an instance of the GemFire XD code that runs in a JVM. A GemFire XD member can optionally host data, provide network server functionality for client connections, and provide location services for the distributed system.
A GemFire XD distributed system is dynamic, and members can be added or removed at any time. The GemFire XD implementation guarantees a consistent view of the distributed system to ensure that data consistency and data integrity are not compromised.
Most GemFire XD members are configured to host data, and are referred to as data stores. Members that are configured to not host data are referred to as accessors. Both data stores and accessors can execute the DDL and DML commands that GemFire XD supports. Data stores provide single-hop or no-hop access to data stored that is stored on members of the distributed system. Accessors provide single-hop access to data stores in the distributed system.
A third type of member, the standalone locator, does not host data and does not support DDL and DML statements on user-defined tables. You use locators to discover members of the GemFire XD cluster.