3V0-23.25 Questions and Answers

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.

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.

The policy edit is valid for a six-node vSAN ESA cluster because RAID-6 with Failures to tolerate set to 2 requires at least six ESX hosts in the vSphere cluster. However, editing a VM storage policy that is already associated with virtual machine objects does not automatically communicate the new requirements to those objects. vSphere marks the compliance status as Out of Date, indicating that the policy has been edited but the new requirements have not yet been communicated to the datastore where the VM objects reside. The administrator must reapply the VM Storage Policy to the affected objects before vSAN evaluates the new RAID-6 requirement and begins any layout changes or resynchronization needed to bring objects into compliance. The change is not rejected because the cluster satisfies the minimum host count. It is not automatically applied serially to the VMs, and the 60-minute timer is related to repair-delay behavior after failures, not normal storage policy changes. Reference topics: Reapply Virtual Machine Storage Policy, Out-of-Date Compliance, vSAN ESA RAID-5, vSAN ESA RAID-6.

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.

Deploy ESX 9.x

Configure to use NVMe storage

Deploy vCenter 9.x

Deploy the VCF Installer Appliance

Download binaries for the installation

Deploy VCF 9.x using existing components as building blocks

Add additional components

The sequence begins with deploying ESX 9.x on the blade hosts because the hosts are the physical foundation for the future management domain. Since there is no local storage beyond the operating system and the external array supports NVMe/TCP only, the hosts must then be configured to use NVMe storage before vCenter is deployed. This provides the required shared datastore for the vCenter deployment and for later VCF management component placement. After the NVMe storage is accessible, vCenter 9.x is deployed to manage the ESX hosts and form the existing vSphere building block. The convergence process then moves into the VCF workflow: deploy the VCF Installer Appliance, download the required binaries to the installer appliance, and deploy VCF 9.x by using the existing vCenter and ESX hosts as starting building blocks. Because Aria Operations is not currently deployed, VCF Installer deploys the required missing components during the converge process, and remaining additional components are added after the core platform deployment is complete. Reference topics: Converging Existing Virtual Infrastructure, VCF Installer, Existing Components as Building Blocks, NVMe Storage Preparation.

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.

The administrator must validate that the vSphere Native Key Provider has been backed up. When a Native Key Provider is created, vCenter pushes the key provider configuration to clustered ESX hosts, but the provider is not usable for encryption tasks until it has been backed up. The documentation states that after adding a Native Key Provider, it appears as not backed up, and that it must be backed up before use. The backup process changes the provider status from Not Backed Up, to Warning while vCenter propagates information to hosts, and then to Active when the information has been pushed to all hosts. A TPM 2.0 device is not required when using Native Key Provider with default settings, although TPM can provide enhanced security and can optionally be enforced. Crypto Safe Mode and disabling Secure Boot are not prerequisites for enabling vSAN Data-at-Rest Encryption with NKP. Therefore, the validation step is to confirm that the NKP backup has been created and the provider is active on the hosts. Reference topics: vSphere Native Key Provider, Back Up Native Key Provider, vSAN Data-at-Rest Encryption, Key Provider Availability.

The workload domain should use Fibre Channel as principal storage because the existing five hosts already have resilient HBAs and are connected to a dedicated, highly resilient storage area network. The third-party block storage is also stated to have sufficient scale, capacity, and IOPS for the new workload requirements only, so it should be reused where it directly fits: the VI workload domain. VMware Cloud Foundation supports Fibre Channel as both principal and supplemental storage for VI workload domains. The management domain should use VMware vSAN as principal storage because the four new servers are being purchased for the management domain, and the existing block storage is not sized for management workloads. vSAN is a native VCF principal storage model for management domains and provides automated deployment, policy-based management, lifecycle integration, and integrated operations. iSCSI is not the right answer because the scenario describes Fibre Channel SAN connectivity and HBAs, not an iSCSI design. vSAN for the workload domain would also fail the reuse requirement because it would ignore the existing block storage investment. Reference topics: Principal Storage, Fibre Channel Storage Model, vSAN Storage Model, Management Domain Storage.

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.

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.

The two major contributors are RAID overhead and Operational Reserve. With the default policy set to FTT=1 using RAID-1 mirroring, vSAN stores two copies of protected data. The capacity planning guidance states that when Failures to tolerate is set to 1 failure with RAID-1 mirroring, virtual machines can use about 50 percent of raw capacity because each object consumes mirrored space. This is the largest capacity-impacting factor. The second contributor is Operational Reserve, which reserves capacity for vSAN internal operations such as policy changes, rebalancing, object movement, and other transient storage activities. Even when Host Rebuild Reserve is not activated, vSAN capacity monitoring still accounts for the operations threshold/reserve needed to keep the cluster functional during internal activity. Encryption overhead is typically not the primary reason for a 20% capacity difference. Host upgrade overhead is not a vSAN capacity category. VM swap can consume capacity, but it does not normally account for most unavailable raw capacity compared with RAID mirroring and operational reservation. Reference topics: vSAN Capacity Planning, RAID-1 FTT=1 Capacity Impact, Operations Reserve, Reserved Capacity.