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.

The extended resync behavior is best explained by deduplication and compression in a vSAN OSA design. In vSAN OSA, deduplication and compression are enabled at the cluster level but applied on a disk-group basis. The documentation states that deduplication occurs inline when data is written back from the cache tier to the capacity tier, and compression is then applied as data moves from cache to capacity. During resynchronization, vSAN must read, rewrite, deduplicate, compress, and destage data through this disk-group architecture. That additional processing can extend resync duration even when the physical network and hardware are healthy. "Ensure Accessibility" does not trigger a full component migration; it evacuates only enough data to maintain object accessibility and may leave objects temporarily noncompliant. The number of disk groups is not inherently the cause, and NVMe cache devices are not automatically limiting throughput simply because they are used in the cache tier.
The key differentiator in the scenario is that deduplication and compression are enabled while heavy resync activity is occurring. Reference topics: vSAN OSA Deduplication and Compression, Disk Group Scope, Cache-to-Capacity Destaging, Maintenance Mode, Resynchronization.

Disabling the vSAN iSCSI Target Service stops the service that presents iSCSI targets and LUNs to initiators, but it does not automatically delete the targets or LUNs. The vSAN administration guidance states that if an administrator wants to remove vSAN iSCSI objects and reclaim capacity, the LUNs and targets must be deleted manually before or after disabling the service. Therefore, when the service is disabled, the existing targets and LUNs remain in the vSAN datastore but are no longer accessible to the clustered legacy application. This behavior prevents accidental deletion of application or quorum data simply because the service is turned off. The targets are not archived for a fixed retention period, and they are not automatically migrated to another namespace for retention. They are also not deleted automatically. Operationally, administrators should confirm that the legacy application no longer depends on the LUNs before disabling the service or should remove the iSCSI objects through the supported workflow when decommissioning is complete. Reference topics: vSAN iSCSI Target Service, Disable iSCSI Target Service, LUN and Target Lifecycle, vSAN Object Retention.

NFS v3 is the best recommendation because the scenario provides only Ethernet-based host connectivity and no budget for additional hardware. Fibre Channel would require appropriate FC HBAs, SAN zoning, and array presentation to all hosts. The provided hosts only have Ethernet NICs and local boot/storage devices, so they are not prepared for FC without additional hardware. VMware Cloud Foundation supports NFS as principal storage for VI workload domains, but the supported principal NFS protocol version is NFS v3. NFS v4.1 is supported as supplemental storage, not as principal storage for this use case. The documentation also states that when NFS is used as principal storage with vSphere Lifecycle Manager images, only two hosts are required, matching this two-host scenario. Fibre Channel over Ethernet is not the appropriate supported principal storage option in this VCF storage model. Therefore, NFS v3 uses the existing network capability, avoids new hardware spend, and aligns with the supported VCF principal storage model. Reference topics: Principal Storage, NFS Storage Model, VI Workload Domain Storage, Fibre Channel Prerequisites.