Your environment currently has a 12-node NetApp cluster serving iSCSI. You need to add at least four more nodes to serve FC to your environment. In…

NetApp ONTAP architecture specifies different maximum cluster sizes based on the protocols being served. A cluster configured for Network Attached Storage (NAS) or unified (NAS and SAN) workloads can scale up to 24 nodes. However, a cluster configured exclusively for Storage Area Network (SAN) protocols—which include iSCSI, Fibre Channel (FC), and NVMe/FC—is limited to a maximum of 12 nodes (6 HA pairs).

The scenario describes a 12-node cluster currently serving iSCSI and needing to add nodes to serve FC. Since both are SAN protocols, the environment is considered SAN-only. The existing cluster is therefore already at its maximum supported size, and no additional nodes can be added to it. The only valid solution is to create a new cluster for the additional controllers.

A. You can safely add up to 4 more storage controllers in the current cluster

This is incorrect. Adding 4 nodes would create a 16-node cluster, which exceeds the 12-node maximum limit for a SAN-only ONTAP cluster.

B. You can safely add up to 6 more storage controllers in the current cluster

This is incorrect. Adding 6 nodes would create an 18-node cluster, which is not a supported configuration for a SAN-only environment.

D. You can safely add up to 12 more storage controllers in the current cluster

This is incorrect. A 24-node cluster is the maximum size for NAS or unified clusters, but it is not supported for clusters running only SAN protocols.

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1. NetApp ONTAP 9 Documentation, "System administration > Cluster and SVM administration overview > Cluster components":

"A cluster can contain up to 24 nodes (12 HA pairs) if the cluster is configured to use NAS protocols. A cluster can contain up to 12 nodes (6 HA pairs) if the cluster is configured to use only SAN protocols (FC, FCoE, iSCSI, and NVMe/FC)." This directly states the architectural limit that governs the scenario.

2. NetApp Technical Report TR-4571, "ONTAP 9 Best Practices and Implementation Guide":

Section 2.1, "Cluster Sizing": "ONTAP clusters support up to 24 nodes for NAS and unified SAN and NAS environments. For SAN-only environments, ONTAP clusters support up to 12 nodes." This technical report reinforces the distinction between SAN-only and unified cluster scale limits.

3. NetApp ONTAP 9 Documentation, "Cluster administration > Add nodes to a cluster > Considerations for adding a node to a cluster":

The documentation on cluster expansion prerequisites states, "You should verify that adding a node does not cause the cluster to exceed its licensed node limit or the platform-based node limit for the cluster." This implies adherence to the documented maximums, which are 12 for SAN-only and 24 for NAS/Unified.