# About SDS Element Relationships

- Network or cluster elements that share data among each other at the same scope are defined as belonging to the same "data sharing community". The following graphic shows three data sharing communities:

- Cluster 1 (Community 1) and Cluster 2 (Community 2) are sharing Class of Service (COS) data at the cluster scope

- At the network scope (Community 3), six elements are sharing Feature Access Code (FAC) data

- Two elements, which may or may not belong to the network, are not sharing any data with other elements.

- A System Data Synchronization community consists of two or more member elements some of which can function as one or more "master" elements.

- A "master element" is the element that you are logged into when you initiate a synchronization or update a form record (add, edit, or delete).

- All other elements that belong to the same SDS community (network or cluster) as the master element are referred to as "member elements".

- Because the SDS master-member element relationship is not enforced, you can have two or more elements functioning as master elements concurrently.

- Within a data-sharing network or cluster, each master element recognizes all other elements as members of its own data sharing community, whether those members are functioning as masters or not.

NOTE: Do not use an AX controller as the master element in a cluster or network. The AX controller does not have enough storage space to maintain a large number of SDS pending updates and errors.

Related Topics

- About the SDS Forms

- Performing Concurrent Synchronizations