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

A shallow rekey operation rotates only the Key Encryption Key (KEK). In vSAN Data-at-Rest Encryption, vCenter obtains or generates the KEK through the configured key provider, while ESX hosts use Data Encryption Keys (DEKs) to encrypt the actual disk or object data. The KEK is used to protect, or wrap, those DEKs. When a shallow rekey is performed, the underlying encrypted data does not need to be rewritten because the DEKs remain the same; only the KEK changes, and the existing DEKs are re-encrypted with the new KEK. This is why shallow rekey is faster and less disruptive than a deep rekey. A deep rekey generates both a new KEK and new DEKs, requiring re-encryption of data. The Host Key is used for encrypted core dumps, not datastore data encryption. Key Derivation Key is not the key rotated in this vSAN shallow rekey workflow. Reference topics: vSAN Data-at-Rest Encryption, Generate New Encryption Keys, Shallow Rekey, Deep Rekey, KEK and DEK lifecycle.

vSAN Stretched Clusters meet the availability-zone requirement by extending a single logical vSAN cluster across two availability zones and using a witness for quorum. This provides rapid recovery from a site or availability-zone failure because workloads remain protected by the stretched topology and vSAN site-failure tolerance. vSAN Storage Cluster addresses the need for scalable, high-performance storage that can grow independently as application capacity requirements increase. In VCF 9.0, a vSAN Storage Cluster is based on vSAN ESA and provides disaggregated storage to vSAN compute or HCI clusters. This design supports storage-dense NVMe-based nodes, high IOPS, low latency, independent capacity scaling, and centralized storage services. Encryption at rest and in transit are native vSAN capabilities that can be enabled on the vSAN-backed storage architecture. vSAN File Service is for file shares, and vSAN iSCSI Target Service is for presenting block LUNs to external initiators; neither is required by the stated application-storage design. vSAN Data Protection is valuable for snapshots and recovery points, but the core architecture requirements are best satisfied by stretched site resilience plus scalable vSAN storage clustering. Reference topics: vSAN Storage Cluster, vSAN Stretched Cluster, vSAN ESA, vSAN Encryption.

vSAN datastores are not managed through datastore clusters and Storage DRS in the same way as traditional VMFS or NFS datastore collections. A vSAN cluster exposes a distributed vSAN datastore, and VM placement, resilience, space efficiency, and compliance are controlled through vSAN Storage Policy Based Management rather than Storage DRS. The scenario also includes mixed vSAN OSA and vSAN ESA storage across clusters, which introduces an additional compatibility concern. vSAN OSA and vSAN ESA datastores are different architectures and are not combined into a single datastore-cluster construct for uniform Storage DRS placement. A datastore cluster should not combine different storage architectures such as vSAN, Fibre Channel, and NFS because Storage DRS assumes similar, interchangeable datastore resources. Creating a datastore cluster through APIs does not make vSAN datastores supported in this model. Therefore, the administrator should consider that vSAN datastores are not supported in datastore clusters and should use vSAN storage policies and appropriate datastore selection instead. Reference topics: vSAN Datastores, Storage Policy Based Management, Datastore Cluster Requirements, vSAN OSA and ESA Compatibility.

The architect should highlight that quotas and Access Based Enumeration are configured when creating the vSAN file share, with ABE available for SMB shares. In the vSAN File Service create-share workflow, the General page allows the administrator to choose the protocol and configure protocol-specific options. When SMB is selected, the share can be configured with Access Based Enumeration, which displays only files and folders that the user has permission to access and hides files or folders where the user lacks Read or equivalent permissions. The same create-share workflow also includes Storage space quotas, including a share warning threshold and a share hard quota. Therefore, the design implication is operational: quotas and ABE must be planned and applied at the file-share configuration level for SMB shares that require both controls. Quotas are not limited only to NFS shares, and ABE is not a cluster-level setting. Separate file service servers are also unnecessary because vSAN File Service supports SMB and NFS shares through the same file service architecture. Reference topics: vSAN File Service, Create vSAN File Share, SMB Access Based Enumeration, Storage Space Quotas.

After vSAN File Services has been deployed, the editable settings are primarily related to the File Service domain network configuration. The vSAN File Service workflow allows modification of primary IP addresses, static IP addresses, and DNS names. These values define how the file service endpoints are presented to clients and how file server instances are resolved on the network. The File Service domain can be adjusted by editing the network configuration and adding or removing IP addresses as needed. The Active Directory domain is not treated as a simple post-deployment editable field because changing domain membership can disrupt authentication, permissions, and file-share access. The Active Directory username and Organizational Unit are part of the directory integration and domain-join configuration, but they are not the three standard settings identified for modification after the initial File Services configuration. Therefore, the three modifiable settings are Static IP addresses, Primary IP addresses, and DNS names. Reference topics: vSAN File Service, Edit File Service Domain, File Service Network Configuration, Active Directory Integration.

Full Clone from Volume Snapshot

4kn Support

Online Volume Expansion

Offline Volume Expansion

Static Persistent Volume

VMware Kubernetes Service persistent volumes use vSphere storage integrations such as CNS and pvCSI to provide Kubernetes storage services backed by vSphere datastores and storage policies. The supported persistent volume capabilities include Static Persistent Volume, which allows pre-existing storage to be consumed by Kubernetes workloads; Offline Volume Expansion and Online Volume Expansion, which allow persistent volumes to be resized depending on workload and filesystem state; Full Clone from Volume Snapshot, which enables a new volume to be created from an existing snapshot; and 4kn Support, which supports modern 4K native storage devices where the underlying stack supports them. Storage vMotion with attached Persistent Volumes is not supported because moving an attached Kubernetes persistent volume while it is in active use can break attachment and consistency assumptions. Storage DRS is also not a supported persistent volume capability in this VKS context. Flash Read Cache is not part of the supported VKS persistent-volume capability set. Reference topics: VMware Kubernetes Service Storage, CNS, pvCSI, Persistent Volume Capabilities, Volume Expansion, Volume Snapshot Clone.

The cluster must not include hosts from different subnets or networks (L3).

The default management vSphere cluster must already be stretched.

The cluster must not include DPU-backed hosts.

The cluster must not share a vSAN Storage Policy with any other cluster.

To stretch a vSAN cluster in a VCF Workload Domain, the environment must satisfy specific VCF stretch prerequisites and avoid unsupported configurations. The default management vSphere cluster must already be stretched so the management plane remains available if an availability zone fails. The workload cluster must not include hosts from different subnets or Layer 3 networks because the stretch workflow expects supported site and network placement assumptions for the cluster being stretched. The cluster must also not include DPU-backed hosts, because clusters with DPU-backed hosts are excluded from this stretch operation. In addition, the cluster must not share a vSAN Storage Policy with any other cluster, because shared policies can create policy scope and compliance conflicts during stretch configuration. SSH does not need to be manually activated on all hosts as a prerequisite. The default management cluster being “not stretched” is the opposite of the required condition. Host self-signed certificates are not the listed blocking condition for this workflow. Reference topics: Stretch vSAN Cluster in VCF, Workload Domain Stretch Prerequisites, vSAN Storage Policy Constraints, Unsupported Stretch Configurations.

Linked clone is the correct feature because the administrator needs to test a potentially destructive change without directly modifying the production VM. vSAN Data Protection uses native vSAN ESA snapshot technology to protect virtual machines through protection groups and scheduled snapshots. Beyond simple restore operations, vSAN Data Protection supports clone workflows that allow a VM to be created from a protected snapshot for development, validation, testing, or recovery use cases. A linked clone is especially appropriate because it can be created quickly from an existing snapshot while maintaining dependency on the base snapshot, avoiding the time and capacity impact of a full independent copy. Immutable snapshots protect recovery points from deletion or modification, but they do not themselves provide an isolated test VM. Multiple schedules only control snapshot timing. A protection group defines which VMs are protected. Replication is used for site-level protection and disaster recovery, not for rapidly testing a destructive change against a local production snapshot. Reference topics: vSAN Data Protection, Snapshot Service, Protection Groups, Linked Clone from Snapshot, VM Test and Recovery Workflows.

In vSAN ESA, the observed three disk stripes are expected behavior for objects using RAID-1, even when the storage policy shows “Number of disk stripes per object = 1.” The vSAN policy rule defines the minimum number of capacity devices across which each replica of an object is striped, and the default value is 1. However, VMware documentation explicitly notes that objects in a vSAN ESA cluster with RAID-0 or RAID-1 configuration have 3 disk stripes, even if the default storage policy defines only 1 disk stripe. Therefore, the three stripes are not caused by site mirroring itself, nor by the VM having three objects. Site mirroring controls placement across the preferred and secondary sites in a stretched cluster, while Failures to tolerate with RAID-1 controls local host/device protection. The behavior is also not evidence that a VM-level policy override exists. The datastore-level policy can still be applied correctly; ESA’s internal RAID-1 object layout uses three stripes as part of its optimized storage architecture. Reference topics: vSAN ESA Default Storage Policy Characteristics, Number of Disk Stripes per Object, RAID-1 Mirroring, vSAN Stretched Cluster Storage Policies.

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.

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.

The Repair Delay Timer expires, and vSAN starts automatic repair evaluation.

Once data resync completes, objects are marked as Compliant again.

vSAN verifies policy requirements and rebuilds missing components on available capacity devices.

When a host goes offline unexpectedly, vSAN treats the missing components as absent and waits for the configured repair delay timer before initiating rebuild operations. This prevents unnecessary resynchronization when a host or device returns quickly. In this scenario, the host is offline for more than an hour, so the repair delay timer expires and vSAN begins automatic repair evaluation. vSAN then checks the assigned storage policies, available capacity, and fault-domain placement requirements to determine whether missing components can be rebuilt safely on available capacity devices. If sufficient capacity and fault domains exist, vSAN creates replacement components and starts resynchronization. When the resync process finishes and the affected objects again satisfy their assigned policies, the objects are marked Compliant. The administrator does not need to manually run a resync task from vCenter, and the host does not need to be placed into maintenance mode for automatic repair. A full cluster rebalance is a separate capacity-balancing operation and is not required before object repair. Reference topics: vSAN Repair Delay Timer, Object Compliance, Resynchronization, ESA Object Repair.

Dedicated VMFS datastores on assigned Fibre Channel arrays meet both the performance and separation requirements. VCF supports Fibre Channel-backed VMFS as principal storage for workload domains, making it valid as the primary datastore type for the tier-1 business application cluster. Fibre Channel provides low-latency block storage, resilient pathing, SAN zoning, LUN masking, and mature enterprise performance characteristics. Because the existing FC arrays are partitioned by business unit, dedicated datastores preserve organizational separation and avoid mixing business-unit workloads on shared storage resources. The same dedicated FC-backed VMFS approach can also be used as supplemental storage after the workload domain exists, allowing extra capacity or specialized tiers while maintaining separation. Shared VMFS datastores do not satisfy the organizational separation requirement because they allow multiple business units to consume the same datastore boundary. vSAN is explicitly excluded, so the design must rely on supported non-vSAN storage. Automated VM placement can be supported by VMFS datastore clusters and Storage DRS where datastores are compatible and similarly managed. Reference topics: Fibre Channel Storage Model, VMFS Datastores, Principal Storage, Supplemental Storage, Datastore Clusters.

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.

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.

A witness host for a 2-node vSAN cluster must be external to the 2-node vSAN-enabled data cluster. The witness provides quorum and must be placed outside the protected data-node pair so that it can arbitrate availability during host or site failure. If the proposed witness host resides inside the 2-node vSAN enabled cluster, it is not eligible and therefore does not appear as an available selection during the replacement workflow. Having a VMkernel adapter configured with vSAN traffic enabled is required for witness communication, so that is not the cause of the issue. Connectivity to the data hosts is also expected and does not make the witness invalid. A witness host already assigned to another 2-node vSAN cluster is not necessarily disqualified because shared witness configurations are supported within scale and sizing limits. The core eligibility issue is that the witness host cannot be a member of the same 2-node vSAN cluster that it is intended to witness. Reference topics: 2-Node vSAN Cluster, Witness Host Placement, Replace Witness Host, Shared Witness Support.

Immutable snapshots are intended to provide hardened recovery points for cyber-recovery scenarios. In vSAN Data Protection, immutability is enabled at the protection group level. Once enabled, snapshots are read-only recovery points that cannot be modified or deleted, even by an attacker with administrative privileges. This immutability model imposes operational restrictions. A VM with immutable snapshots should not have its virtual hardware changed because hardware changes can alter the VM configuration state associated with protected recovery points. In addition, a protection group cannot be configured as both replicated and immutable, because replication and immutable local snapshot protection are separate protection behaviors with different lifecycle and retention handling. The statement that a VM cannot be part of multiple protection groups is not the specific limitation tested here. The number of snapshot schedules is not limited to seven by this requirement. Virtual hardware version 10 is also not the controlling condition for immutable snapshot configuration in this context. Reference topics: vSAN Data Protection, Immutable Snapshots, Protection Groups, Cyber-Recovery Snapshot Restrictions.

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.

The readings indicate a write-path pressure condition rather than a read-cache, network, or device-health issue. In vSAN ESA, storage devices are organized into a storage pool architecture where NVMe devices contribute both capacity and performance. The dashboard shows low read latency and normal network throughput, so the read path and vSAN network are not the likely bottlenecks. Disk Group Health being green also rules out an obvious device or pool-health failure. AI inferencing environments can still create bursts of small random writes from logs, metadata updates, temporary files, checkpoints, and application-side write activity. When backend write latency rises while reads remain low, the most likely explanation is transient write-buffer or commit-queue pressure. ESA does not use the traditional OSA read-cache tier model, so option B is incorrect. ESA also does not rely on OSA-style inline deduplication and compression behavior for the stated cause, making option C incorrect. Normal network throughput makes option D unlikely. Reference topics: vSAN ESA Architecture, Storage Pool Metrics, Backend Write Latency, VCF Operations Storage Performance.