Storage area networks and network-attached storage are given as examples of what?

1. The definition names both examples directly: "Shared-disk file systems, such as storage area networks (SANs) and network-attached storage (NAS), use a single storage pool, which is accessed from multiple computing resources." 2. The distinguishing feature is the single storage pool. Many machines compute, but they all reach into one shared store. 3. Distributed file systems are the contrasting arrangement, defined as containing "multi-structured (object) datasets that are distributed across the computing nodes of the server cluster(s)". There the storage itself is spread out, one piece per node. 4. That contrast is why shared-disk systems sit awkwardly with the Big Data Paradigm: the paradigm calls for horizontally coupled independent resources, and a single shared pool is a point where independence breaks down. 5. A federated database system is defined separately as "a type of meta-database management system, which transparently maps multiple autonomous database systems into a single cohesive database". Non-relational models are logical data models, not storage arrangements at all. _Source: NIST SP 1500-1r2 "NIST Big Data Interoperability Framework: Volume 1, Definitions" (Oct 2019), p.7 section 2 "Terms and Definitions"_