Explanation: To protect a virtual machine against a disk or disk group failure, the storage policy must have a failure tolerance method (FTM) of RAID-1 or RAID-6 and a failure to tolerate (FTT) value of at least 1. RAID-1 mirrors the data across multiple disk groups, while RAID-6 uses erasure coding to stripe the data and parity information across multiple disk groups. RAID-5 is not suitable for this scenario, as it can only tolerate one disk failure per stripe. FTT 2 or 3 would require more disk groups than available in the cluster. Therefore, the correct options are C and E. References: 1, page 8; 2, section 3.1

Explanation: To ensure the latest network driver is installed on the NIC before remediation, the vSAN administrator should add an individual component to the vLCM image that has the updated NIC driver. This action allows the administrator to override the driver provided by the vendor add-on and use a newer version that is compatible with the ESXi version and the hardware device. The administrator can add an individual component to the vLCM image by importing it from a ZIP file or selecting it from the vLCM depot. The other options are not correct. Making sure the vLCM image is configured to use the most recent version of the vendor add-on will not help, as the required NIC driver is a newer version than the one provided by the vendor add-on. Removing the vendor add-on from the vLCM image or modifying the vLCM image to omit the NIC driver will not ensure the latest network driver is installed on the NIC, as these actions will leave the NIC without any driver update. Manually installing or updating the network driver on the servers is not recommended, as it might cause inconsistency and non-compliance in the vLCM image. References: vSphere Lifecycle Manager Image Components; [Add an Individual Component to an Image]

Explanation: To restore the health of the vSAN cluster with minimum risk, the vSAN administrator must remove the devices from the storage pool, replace the storage devices, and claim the new devices in vSAN. This is because removing and replacing devices in a storage pool does not affect the availability or performance of the objects stored in that pool. The storage pool automatically rebalances the objects across the remaining devices in the pool when a device is removed, and distributes the objects across the new devices when they are added. This process is faster and safer than removing and re-adding a host to the cluster, which requires resynchronization of all objects on that host4 References: 4: VMware vSphere Storage Guide, page 133 : VMware vSAN Design and Sizing Guide, page 38

Explanation: The updated policy is serially applied to the virtual machines is the correct answer because changing the rule in the assigned policy will trigger a policy compliance check and a resynchronization of the affected objects. The policy change will not be rejected, queued, or ignored, as it is a valid and supported operation. However, the policy change will not be applied in parallel, as that would cause too much network and disk traffic. Instead, the policy change will be applied one virtual machine at a time, starting with the most critical ones, until all virtual machines are compliant with the new policy.

Explanation: When a host in a vSAN stretched cluster goes offline, vSAN will use Adaptive Resync to recalculate the quorum on an object. Quorum is the minimum number of votes that an object needs to be available. For example, a RAID-1 object with two data components and one witness component needs two votes out of three to be available. If one data component goes offline, the object still has quorum and is available. However, if both data components go offline, the object loses quorum and is unavailable. Adaptive Resync will adjust the quorum requirement based on the availability of components and fault domains. For example, if one fault domain goes offline, Adaptive Resync will lower the quorum requirement to one vote out of two, so that the object can remain available with one data component and one witness component.

Explanation: The minimum required number of hosts to provide data redundancy for a vSAN stretched cluster using dual-site mirroring and local protection with 1 failure - RAID-1 (Mirroring) is six hosts. This is because a vSAN stretched cluster requires at least three hosts per site, and each site must have enough hosts to tolerate one host failure. Therefore, the minimum configuration is three hosts per site, plus one witness host at a third site, for a total of six hosts.

Explanation: To add 30 additional vSAN ReadyNodes to an existing vSAN cluster with the fastest approach, the vSAN administrator should use a Host Profile that was extracted from an existing host. AHost Profile is a configuration template that captures the settings of a reference host and applies them to other hosts or clusters. This way, the administrator can quickly and consistently configure multiple hosts with the same settings, such as network, storage, security, and services. The other options are not correct. Running vim-cmd to capture and apply the configuration from an existing host is not as fast or convenient as using a Host Profile, as it requires running commands on each host individually. Launching Quickstart to Add Hosts to a vSAN Cluster is not possible, as Quickstart is only available for new clusters or clusters that were configured through Quickstart. Cloning the ESXi boot partition to all new hosts is not recommended, as it might cause conflicts or errors with the host identity, network settings, or licenses. References: Configuring Hosts Using Host Profile; Using Quickstart to Configure and Expand a vSAN Cluster

Explanation: The two prerequisites for using the TRIM and UNMAP capability of vSAN are:
B. The vSAN cluster is an all-flash architecture. TRIM and UNMAP are only supported on all-flash vSAN clusters, as they can reclaim space from flash devices that use thin provisioning. TRIM and UNMAP are not supported on hybrid vSAN clusters, as they cannot reclaim space from magnetic disks that use thick provisioning1.
D. TRIM and UNMAP is enabled. TRIM and UNMAP are disabled by default in vSAN, as they might have a performance impact on some workloads. To enable TRIM and UNMAP on a vSAN cluster, the administrator must use the following RVC command: vsan.unmap_support –enable2. After enabling TRIM and UNMAP, the administrator must power off and then power on all VMs that use the vSAN datastore.

Explanation: To achieve the best performance for the database virtual machines and tolerate two host failures in a vSAN OSA cluster, the administrator must use RAID-1 as the RAID configuration in the storage policy. RAID-1 is a mirroring technique that creates multiple replicas of each object across different hosts. RAID-1 provides the best performance among the available RAID configurations, as it does not involve any parity calculations or stripe splitting. To tolerate two host failures, the administrator must set the Failures to Tolerate (FTT) policy to 2, which means that each object will have three replicas. The other options are not correct. RAID-5 and RAID-6 are erasure coding techniques that split each object into data segments and parity segments across different hosts. RAID-5 can tolerate one host failure, while RAID-6 can tolerate two host failures. However, both RAID-5 and RAID-6 have lower performance than RAID-1, as they involve more complex calculations and network traffic. RAID-0 is a striping technique that splits each object into multiple stripes across different hosts. RAID-0 does not provide any data redundancy or fault tolerance, and therefore cannot tolerate any host failure. References: RAID Configurations, FTT, and Host Requirements; RAID 5 or RAID 6 Design Considerations

Explanation: vSAN will use a 4+1 RAID-5 data placement scheme with parity will be used is the correct answer because vSAN 8 ESA uses adaptive RAID-5 erasure coding that depends on the number of hosts in the cluster. If the cluster has 6 or more hosts, vSAN will use a 4+1 RAID-5 scheme, where the data is written as a stripe of 4 data bits and 1 parity bit across 5 hosts. This provides a failure tolerance of 1 (FTT=1) and a space efficiency of 1.25x. If the cluster has less than 6 hosts (3 to 5), vSAN will use a 2+1 RAID-5 scheme, where the data is written as a stripe of 2 data bits and 1 parity bit across 3 hosts. This also provides a failure tolerance of 1 (FTT=1) but a space efficiency of 1.5x. In this case, the cluster has 5 hosts, so vSAN will use the 4+1 RAID-5 scheme.

The other options are incorrect for the following reasons:
A, vSAN will use a 2+1 RAID-5 data placement scheme with parity will be used, is incorrect because vSAN will only use this scheme if the cluster has less than 6 hosts but more than 2 hosts. In this case, the cluster has 5 hosts, so vSAN will use the 4+1 RAID-5 scheme.
B, RAID 5 will provide an FTT=2 level of protection in this case, is incorrect because RAID 5 can only provide an FTT=1 level of protection, regardless of the number of hosts or the data placement scheme. To achieve an FTT=2 level of protection, vSAN would need to use RAID 6 erasure coding, which requires at least 6 hosts in the cluster.
D, vSAN will spread the components across all of the disk groups, is incorrect because vSAN will not necessarily spread the components across all of the disk groups in the cluster. vSAN will only spread the components across as many disk groups as needed to meet the storage policy requirements and to balance the load and capacity. In this case, vSAN will only need to spread the components across 5 disk groups for each stripe of RAID-5 data. References:

VMware vSAN Specialist v2 Exam Preparation Guide, page 11 Adaptive RAID-5 Erasure Coding with the Express Storage Architecture in vSAN 8

Explanation: To perform maintenance on one of the hosts in a three-node vSAN cluster with the best availability for the VMs with the least effort and data transfer, the maintenance mode option that should be used is Ensure accessibility. This option migrates only enough components to ensure that all accessible VMs remain accessible, but does not guarantee full data redundancy or policy compliance. This option is also the only evacuation mode available for a three-node cluster or a cluster with three fault domains, as there are not enough hosts to perform full data migration or re-protection after a failure. The other options are not correct. Migrating all VMs and their storage from the host to a different storage system or a different vSphere cluster would require more effort and data transfer than using Ensure accessibility, as well as additional resources and configuration steps. Full data migration is not possible in a three-nodecluster, as it would require at least four hosts to evacuate all data from one host and maintain full redundancy and policy compliance. References: Place a Member of vSAN Cluster in Maintenance Mode; Working with Maintenance Mode

Explanation: The Skyline Health interval validates online if there are new Health Checks available for vSAN every 24 hours. This means that vSAN checks for new health checks from VMware Analytics Cloud once a day and updates the vSAN Health Service accordingly. The other options are not correct, as they do not match the actual frequency of the online validation. References: About the vSAN Skyline Health