3V0-23.25 Advanced VMware Cloud Foundation 9.0 Storage Question and Answers

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 must be used as principal storage because the hosts have no local storage available. vSAN OSA and vSAN ESA both require local storage devices on the ESX hosts to create the vSAN datastore, so neither can be selected as principal storage in this design. NVMe over RDMA is supported as a high-performance NVMe over Fabrics transport in vSphere, but in the VCF storage model it is treated as supplemental storage rather than principal storage for workload domain creation. Therefore, NVMe over RDMA cannot be the initial principal datastore used to build the Workload Domain. NFS is the valid principal storage option from the provided choices, and after the Workload Domain is created, NVMe over RDMA can be added as supplemental storage for additional performance or capacity use cases. This build order satisfies the lack of local disks, uses a supported principal storage type, and allows the NVMe over RDMA design requirement to be met after the domain exists. Reference topics: Principal Storage, Supplemental Storage, NFS Storage Model, NVMe over RDMA, VCF Workload Domain Storage Design.

The design requires four hardware corrections. First, RAID-6 with FTT=2 requires six fault domains or hosts because RAID-6 erasure coding must place data and parity components across enough independent hosts to tolerate two failures. Therefore, four hosts are insufficient and the host count must increase to at least six. Second, Storage Traffic Separation requires sufficient physical NICs to support separate storage and non-storage traffic paths. With two distributed switches and redundant uplinks, the design must increase to four 25 GbE NICs per host. Third, vSAN ESA requires at least 128 GB of host memory; the provided 96 GB is below the minimum. Fourth, NVMe devices attached to a SATA/SAS/NVMe Tri-mode controller are not supported for vSAN storage pools. The documentation states that vSAN supports SAS and SATA devices on Tri-mode controllers, but NVMe devices must be directly connected to PCIe or use a supported NVMe design. The CPU count does not need to increase because 24 cores satisfies the stated vSAN ESA minimum in the referenced design guidance. Reference topics: vSAN ESA Hardware Requirements, RAID-6 FTT=2, Storage Traffic Separation, NVMe Controller Support.

Because the vSAN cluster uses vSphere Lifecycle Manager images, the least disruptive remediation method from the provided choices is to enable Quick Boot in the host remediation settings for images. Quick Boot reduces host remediation time by skipping the full hardware reboot, including the BIOS or UEFI firmware reboot. This reduces the amount of time each ESX host spends in maintenance mode and lowers operational disruption during patching. The documentation states that Quick Boot can be configured for clusters or standalone hosts managed with vSphere Lifecycle Manager images, and that it reduces reboot time during remediation. The baseline options are incorrect because the cluster is explicitly managed by images, not baselines. Disabling Quick Boot would increase disruption because hosts would require a full reboot path. Disabling HA admission control is not the least-disruption patching mechanism and is listed for baseline-oriented remediation behavior in the offered answer. In a vSAN cluster, hosts enter maintenance mode one at a time, so reducing each host’s maintenance window through Quick Boot is the appropriate method. Reference topics: vSphere Lifecycle Manager Images, Host Remediation Settings, Quick Boot, vSAN Cluster Remediation.

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 required action is to deploy the VMware Live Recovery appliance. In VMware Cloud Foundation 9.0, vSAN Data Protection is powered by VMware Live Recovery and provides local virtual machine protection and remote virtual machine replication for supported vSAN ESA environments. The vSAN Services configuration workflow explicitly states that before vSAN Data Protection can be used, the VMware Live Recovery appliance must be deployed. This appliance provides the data protection control plane required for protection groups, native snapshots, recovery workflows, and replication-based protection. Enabling vSAN advanced options is not sufficient because those settings control cluster behaviors such as repair timers, read locality, thin swap, unmap, and rebalance. Data Services Manager is used for database/data-service lifecycle use cases, not vSAN VM data protection. vSphere Replication can be part of broader site-recovery scenarios, but it is not the required action to enable vSAN Data Protection from the vSAN services workflow. Reference topics: vSAN Data Protection, VMware Live Recovery Appliance, vSAN Services Configuration, Local VM Protection and Replication.

The administrator must create a datastore cluster from the three NFS datastores that are intended to host virtual machine workloads. The ISO datastore should not be included because datastore clusters should contain similar or interchangeable datastores used for the same purpose. All three NFS datastores must be available to each ESX host server so Storage DRS recommendations and VM placement are valid across the cluster. Storage DRS should be configured in Manual mode because the requirement states that migrations must occur only after administrator approval. Manual mode displays placement and migration recommendations but does not execute them automatically. The Storage DRS space threshold should be set to 50% so recommendations are generated when a datastore exceeds that utilization level. Setting the storage space utilization difference to 50% is not correct because that value controls the minimum difference between source and destination datastore utilization, not the trigger threshold itself. Fully Automated mode would violate the approval requirement by automatically applying migrations. Reference topics: Datastore Cluster Requirements, Storage DRS, Manual Automation Mode, Space Utilization Thresholds, NFS Datastores.

Four hosts are required to meet the 12 TB usable-capacity requirement after applying the protection policy, data reduction, reserves, and overhead. Each host contributes 8 TB raw capacity from two 4 TB NVMe devices. Three hosts provide 24 TB raw capacity, but once host rebuild reservation, 10% operational reserve, RAID-5 protection overhead, and 25% filesystem/object overhead are considered, the remaining effective usable capacity falls below the required 12 TB target. Four hosts provide 32 TB raw capacity. With vSAN ESA and FTT=1/RAID-5, vSAN uses erasure coding to improve capacity efficiency compared with mirroring. The vSAN sizing guidance states that RAID-5 with FTT=1 provides approximately 75% usable capacity before other reserves and overhead. Host Rebuild Reserve must also be planned so the cluster has enough free capacity to rebuild components after a host failure. After applying the expected 1.5 data reduction ratio and the required reserves, four hosts provide enough usable capacity while three hosts do not. Reference topics: vSAN ESA Capacity Sizing, RAID-5 Erasure Coding, Host Rebuild Reserve, Operations Reserve, vSAN Object Overhead.

When vertically scaling a vSAN ESA cluster, adding the same model and capacity drives helps preserve a balanced and predictable cluster design. vSAN works best when hosts use uniform storage configurations. The guidance states that unbalanced host configurations reduce predictability of storage performance because vSAN does not store the same number of components on each host, can introduce different maintenance procedures, and can reduce performance on hosts with smaller or different device types. In ESA, each storage device contributes both capacity and performance through the storage pool model, so mixing device models, endurance classes, or capacities can create uneven consumption and inconsistent backend behavior. Using the same drive model and capacity across hosts improves capacity symmetry, keeps maintenance and replacement procedures consistent, and makes performance planning more predictable. The cache-drive option is incorrect because ESA is single-tier and does not use separate cache and capacity tiers. Equal cache and capacity tiers apply to OSA-style thinking, not ESA. vSAN File Services being configured does not drive the requirement to use identical drives. Reference topics: vSAN ESA Storage Pool Design, Balanced and Unbalanced Cluster Configuration, ESA Device Performance, Vertical Scaling.

The correct steps are to create an NFS export on the storage array and mount the NFS datastore on each ESX host in the cluster. NFS datastore creation begins on the storage system, where the storage administrator creates and exports the NFS volume or directory with the required access permissions for the ESX hosts. After the export exists, vSphere mounts that export as a datastore. For a clustered VCF workload domain, the datastore must be mounted consistently across all ESX hosts in the cluster so that HA, DRS, vMotion, and VM placement can operate correctly. Mounting the datastore on only one host would create inconsistent datastore accessibility and could prevent workloads from moving or restarting on other hosts. “Attach NFS as a secondary datastore” is not the correct procedural step; the datastore is created and mounted as a vSphere datastore. Configuring vSAN is irrelevant because the workload domain already uses NFS storage and the task is to add another NFS datastore. Reference topics: NFS Datastore Creation, NFS Export, Host Accessibility, VCF Workload Domain Storage Administration.

ESA evaluates available capacity and fault domains to satisfy policy compliance.

vSAN detects the failure and marks affected objects as non-compliant.

Resync completes and objects transition to Compliant status.

New components are instantiated on eligible capacity devices, and resync begins.

A failed NVMe device in a vSAN ESA cluster is handled as a storage pool device failure. vSAN first detects the failure and marks affected objects as non-compliant when their assigned storage policy requirements are no longer satisfied. ESA then evaluates available capacity and fault domains to determine whether replacement components can be placed in a way that restores compliance. If sufficient placement resources exist, vSAN creates new components on eligible capacity devices and begins resynchronization. After the resync completes, the affected objects transition back to Compliant status. The Repair Delay Timer is primarily associated with absent components, such as a host or device that may return, and is not the required step for a permanent NVMe failure. The administrator does not have to manually trigger Repair Objects Immediately for the normal automatic repair process. A full cluster rebalance is separate from repair and is not performed before rebuilding missing or degraded components. Reference topics: vSAN ESA Storage Pool Device Failure, Object Compliance, Automatic Reprotection, Resynchronization.

In vSAN ESA, each host uses a storage pool instead of the older OSA disk- group model. The question asks what percentage of that host’s local capacity is impacted by the failure of one storage device. Each host has 12 equal-capacity storage devices, and all 12 devices participate in one storage pool. Therefore, one failed device represents one-twelfth of that host’s local pool capacity. One divided by twelve equals approximately 8.3%. RAID-6 with FTT=2 determines object resilience across hosts and fault domains, but it does not change the simple local-capacity fraction represented by a single failed disk on one host. With sufficient cluster resources and policy compliance, vSAN ESA can continue serving data and begin repair or reprotection using remaining capacity. However, the impacted local host capacity is still the failed device’s share of the host storage pool. The correct percentage is therefore 8.3%, not 25%, 50%, or 0%. Reference topics: vSAN ESA Storage Pools, Storage Device Failure, RAID-6 FTT=2, Capacity Impact Calculation.

VMware vSAN is the correct principal storage for both the Management Domain and the Workload Domain because it is integrated, policy-based, scalable, and managed directly through VCF and vSphere. The Management Domain requirement explicitly calls for a highly scalable integrated storage solution that does not require additional storage management software or hardware, which aligns with vSAN. The Workload Domain also requires a highly scalable, policy-based storage solution for critical application workloads, which again maps directly to vSAN storage policies and vSAN datastore services. The second workload tier requires file-based storage that can scale independently of the cluster for workloads with large data requirements. NFS v3 is supported as supplemental storage and is appropriate for adding file-based capacity without changing the principal vSAN datastore. iSCSI is supplemental only and does not meet the Management Domain principal storage requirement. NFS v4.1 is not the correct principal storage selection for the Management Domain. Reference topics: VCF Storage Models, Principal Storage, Supplemental Storage, vSAN Storage Model, NFS Storage Model.

Windows Server Failover Cluster shared disks require coordinated access to shared block storage. vSAN supports Windows Server Failover Clusters by providing SCSI-3 Persistent Reservation support at the virtual disk level, which allows cluster nodes to arbitrate access to a shared disk resource. One supported approach is to use the vSAN iSCSI Target Service, which presents vSAN-backed LUNs to initiators and can be used for clustered workloads that require shared block access. Another supported approach is to configure a shared virtual disk using a VMware Paravirtual SCSI controller with physical bus sharing. Physical bus sharing allows multiple VMs to access the same shared virtual disk in a WSFC configuration where supported. Raw Device Mapping is not the vSAN ESA-native solution for this requirement. NFS v4.1 is a file datastore protocol, not a WSFC shared block disk mechanism. “LSI SCSI controller per disk” does not satisfy the required shared-disk bus sharing configuration. Reference topics: vSAN Support for Windows Server Failover Clusters, SCSI-3 Persistent Reservations, vSAN iSCSI Target Service, Shared VMDK Configuration.

In a three-node vSAN ESA cluster, the maximum practical storage policy failure tolerance is one failure. RAID-1 mirroring with Failures to tolerate set to 1 is supported because vSAN can place mirrored data components across the available hosts while maintaining quorum. RAID-5 erasure coding with Failures to tolerate set to 1 is also supported in vSAN ESA three-host clusters. The documentation specifically states that RAID-5 in vSAN ESA supports three ESX host clusters. RAID-6 with FTT=2 is not supported because it requires at least six ESX hosts in the vSphere cluster. RAID-1 with FTT=2 would also require additional fault domains because vSAN requires 2n+1 fault domains for n failures tolerated. HA reserved failover capacity for CPU and memory does not change the number of vSAN fault domains available for storage object placement. It only affects compute admission control. Therefore, the two valid maximum protection levels for this three-node ESA cluster are RAID-1 mirroring with one failure and RAID-5 erasure coding with one failure. Reference topics: vSAN ESA Storage Policies, Failures to Tolerate, RAID-1 Mirroring, RAID-5 Erasure Coding, RAID-6 Requirements.

With “Ensure Accessibility,” vSAN migrates only the minimum amount of data required to keep objects accessible while the host enters maintenance mode. This mode is faster than Full Data Migration, but it does not fully reprotect all objects. The documentation states that objects might no longer be fully compliant with their storage policy during this evacuation mode, meaning they might not have access to all replicas. Because the default policy is RAID-1 with FTT=1, each object can tolerate only one failure. While the first host is in maintenance mode, some VM objects are already running in a reduced-availability state. If a second host loses network connectivity during this window, affected objects can lose quorum or access to required components. vSAN does not immediately rebalance or fully rebuild objects simply because Ensure Accessibility was selected, and permanent data loss is not the expected result from a temporary network loss. The likely impact is that some VMs become inaccessible until either the maintenance host returns or the isolated host reconnects. Reference topics: vSAN Maintenance Mode, Ensure Accessibility, Default Storage Policy, RAID-1 FTT=1, Network Partition Handling.

Site A = Data Site; Site B = Witness Site; Site C = Data Site; Site A ↔ Site C = Layer 3, RTT < 5 ms; Site A ↔ Site B = Layer 3, RTT < 200 ms; Site B ↔ Site C = Layer 3, RTT < 200 ms

Site A and Site C should be the data sites because Site A hosts production services and Site C has been commissioned to replace the capacity-constrained Site B. Site B should be used as the witness site because it has no space for additional physical hosts, and a vSAN witness appliance does not run workload VMs. A vSAN Stretched Cluster requires two availability zones for data nodes and a third site for the witness appliance. The data-site-to-data-site connection carries synchronous vSAN data traffic and must meet less than 5 ms RTT. The witness site carries metadata traffic only, so the data-site-to-witness links support higher latency, with less than 200 ms RTT for up to 10 hosts per site. Because the requirement specifically calls out minimizing disruption from STP, Layer 3 is the preferred network type between sites. VMware states that Layer 3 helps avoid STP redirecting traffic across undesirable links, such as constrained witness links. Reference topics: vSAN Stretched Cluster Network Design, Data Site and Witness Site Placement, Layer 3 Recommendation, RTT Requirements.

The device has already been claimed by vSAN, so it is now part of the vSAN ESA storage pool. It must be removed from vSAN through a controlled device-removal workflow before it can be repurposed for memory tiering. The correct method is to remove the device from vSAN using Full Data Migration. This evacuation mode migrates data from the device to other eligible devices or hosts so that objects remain protected and compliant where possible. After the device is safely removed from the vSAN storage pool, it can be configured for memory tiering. Physically removing or hot-removing the device is unsafe because vSAN may still have components on it. Booting without the device is also not a supported configuration workflow. Changing disk claiming behavior and rebooting does not safely remove existing components from the already claimed device. vSAN ESA uses a storage pool model, so claimed NVMe devices contribute capacity and performance; a device intended for another purpose must be explicitly evacuated and removed before reuse. Reference topics: vSAN ESA Storage Pools, Device Claiming, Remove Storage Pool Device, Full Data Migration, Memory Tiering.

vSAN HCI Cluster = A cluster that provides both compute and storage to Virtual Machines;

vSAN Storage Cluster = A vSAN cluster that provides disaggregated storage for vSAN and vSphere clusters;

vSAN Compute Cluster = A vSphere cluster that does not have local vSAN storage, but instead, it mounts a remote vSAN datastore;

vSAN Stretched Cluster = A vSAN Cluster topology that extends a single logical vSAN cluster across two availability zones. A vSAN stretched cluster can tolerate a site failure.

These mappings describe the primary vSAN storage models used in VMware Cloud Foundation 9.0. A vSAN HCI Cluster is the traditional hyperconverged model where the same cluster provides compute resources and contributes local storage devices to the vSAN datastore for running virtual machines. A vSAN Storage Cluster is a disaggregated storage model based on vSAN ESA; it provides storage capacity and performance to other vSAN or vSphere clusters instead of primarily running workloads itself. A vSAN Compute Cluster is a vSphere cluster that does not contribute local vSAN capacity. Instead, it consumes a remote datastore exported by a vSAN Storage Cluster, enabling compute and storage to scale separately. A vSAN Stretched Cluster extends a single logical vSAN cluster across two availability zones or sites and uses a witness to maintain quorum, allowing workloads to tolerate a full site failure. These distinctions are essential for choosing between HCI, disaggregated storage, remote storage consumption, and availability-zone resilience. Reference topics: vSAN HCI Cluster, vSAN Storage Cluster, vSAN Compute Cluster, vSAN Stretched Cluster, VCF Storage Models.