A SAN host has multiple available paths but uses only one path. Which host configuration should be checked?

When a SAN host (using iSCSI or Fibre Channel) has multiple physical paths to a storage controller but is only utilizing a single path, the primary component to investigate is the host's multipath software configuration. Multipathing software, such as MPIO in Windows or DM-Multipath in Linux, is responsible for discovering all available paths, aggregating them into a single logical device, and managing load balancing and failover. If it is misconfigured, disabled, or lacking the correct Asymmetric Logical Unit Access (ALUA) settings, the host will default to using only one path. This misconfiguration leads to suboptimal performance, potential bottlenecks, and a complete lack of redundancy if the single active path experiences a failure or network disruption.

A. Snapshot policy: This dictates the automated schedule for volume snapshots on the storage array, which is unrelated to host SAN pathing.

B. SMB signing: This is a security mechanism for the SMB/CIFS file-sharing protocol, not applicable to block-level SAN multipathing.

D. NFS export rules: These rules control client access to NAS file systems (NFS), which is irrelevant to SAN block storage paths.

1. NetApp ONTAP 9 SAN Configuration Guide, Section: "Host multipathing routing", Paragraphs detailing ALUA and MPIO setup.

2. NetApp SAN Host Configuration Guide, Section: "Multipathing software configuration for Windows and Linux".