High latency in a vSAN cluster is commonly caused by congestion in the backend storage path. Disk group congestion means vSAN is queuing, delaying, or throttling I/O because one or more disk groups cannot service the workload at the required rate. VCF Operations and vSAN performance views expose disk group and device-level congestion indicators, including IOPS congestion, log congestion, component congestion, memory congestion, and SSD congestion. These metrics directly correlate with elevated latency because the virtual machine I/O path must wait for vSAN backend processing to complete. PVSCSI controllers are normally recommended for high-performance virtual disks and are not a typical cause of vSAN latency. Jumbo frames, when consistently configured end-to-end, are a valid network optimization and do not inherently cause latency. Disabled erasure coding would usually reduce parity overhead, not create backend latency. Therefore, disk group congestion is the most likely explanation for high latency shown in the vSAN cluster performance charts. Reference topics: vSAN Performance Service, Disk Group Metrics, Congestion Metrics, vSAN Latency Troubleshooting.

The correct action is to verify the datastore, device paths, and multipathing state in vCenter. Fibre Channel VMFS storage depends on SAN fabric connectivity, HBAs, zoning, LUN masking, storage processors, path selection policies, and multipathing. vCenter provides the operational view needed to confirm whether the FC VMFS datastore is visible to every ESX host in the workload domain cluster. It also exposes storage device path status and multipath health so administrators can validate that redundant paths are active and alarms can trigger when a fabric link or path fails. esxcli vsan storage list is specific to vSAN devices and does not validate external FC VMFS paths. The proposed VCF SDK command is not the standard method for validating FC path and datastore visibility. vmkfstools --inspectpaths is not the normal vSphere workflow for FC LUN health validation. For FC-backed VMFS, vCenter storage views provide the correct centralized validation point. Reference topics: Fibre Channel Storage Model, VMFS Datastore Connectivity, Multipathing, Path Health, vCenter Storage Monitoring.