Coordinating Nodes

What is a Coordinating Node?

There are three major components in the DataONE infrastructure

• Coordinating Nodes, which maintain a complete catalog of all data and provide the core DataONE services, including search and discovery;
• Member Nodes, which expose their data and metadata through a common set of interfaces and services; and
• The Investigator Toolkit, which consists of software tools that have either been written or modified to use the services provided by DataONE Coordinating and Member Nodes.

Coordinating Nodes are all currently managed by the DataONE Core Cyberinfrastructure Team and provide the backbone for the DataONE cyberinfrastructure. By contrast, Member Nodes are generally operated by an organization that manages data, whether primarily just for that organization or for a broader scientific community.

The coordinating nodes are all eqivalent, to provide a fault-tolerant and responsive set of services to DataONE users and Member Nodes. Searches of the DataONE catalog, for example, are done through the comprehensive metadata stored on the coordinating nodes. Member Nodes send their metadata to the coordinating node cloud as the Member Node adds or updates data in their holdings. When users download data, such as through tools in the Investigator Toolkit, those tools call functions at the Coordinating Nodes to determine what Member Node holds that data so that the user can get the data. The Coordinating Nodes also manage the replication of data between Member Nodes, as part of the data preservation process, monitor the health of the DataONE cyberinfrastructure components, and manage user identities, through the use of CILogon accounts.

Currently, there are three coordinating nodes, located at the University of New Mexico, the University of California Santa Barbara and at the University of Tennesse (in collaboration with Oak Ridge National Laboratory). As DataONE grows, we will add more coordinating nodes, with a particular interest in locating coordinating nodes in places to serve users outside of the United States. Organizations that might be interested in operating a coordinating node on behalf of DataONE should contact a member of the DataONE Executive Team to discuss such possibilities.

Coordinating Nodes and Replication

Given that data replication is an important part of DataONE's strategy for data preservation, DataONE has provisioned several hundred terabytes of disk space at the coordinating node sites, to serve as a seed for data replication. As DataONE grows, the vision is that Member Nodes who want to participate in data replication will provide an appropriate amount of disk space at their site to receive data from other Member Nodes. This replication can serve to both assist with data preservation and allow Member Nodes to more rapidly serve data from other Member Nodes to their user community. Note that any access control lists for data are always included with the replication and that Member Nodes are always in control of where their data may be replicated to within DataONE, as well as what data they allow to be replicated into their systems.