A healthy StorageGRID deployment requires one primary Admin Node and at least three Storage Nodes at each site. NetApp StorageGRID 12.0 documentation states that every grid requires a primary Admin Node to provide core management and configuration services, while every site requires a minimum of three Storage Nodes. Therefore, the smallest healthy single-site virtual test environment contains four nodes: one Admin Node plus three Storage Nodes.

The three-Storage-Node minimum is important because Storage Nodes host core distributed services such as Cassandra, DDS, and ADC. In particular, the ADC service is hosted on at least three Storage Nodes at a site, supporting grid topology information, authentication, and service discovery.

Option A lacks the required primary Admin Node and therefore cannot constitute a complete manageable StorageGRID grid. Option D contains an Admin Node but only one Storage Node, which does not satisfy the three-node minimum. Option C would work, but the Gateway Node is optional because Admin Nodes can also provide S3 load-balancing functionality for a small compatibility-test deployment.

Therefore, B is the minimum healthy virtual configuration.

Reference topics: StorageGRID Architecture Grid Node Types Primary Admin Node Minimum Storage Nodes per Site Virtual Deployment Requirements