An administrator is performing maintenance on the hosts in a four-node vSAN cluster and has selected the "Ensure Accessibility" maintenance mode option. All VMs are running with the Default Storage Policy which has not been modified from the default settings.
While one of the hosts in the cluster is down for firmware upgrade, a second host suddenly loses network connectivity to the remaining hosts.
How will the cluster be affected?
In a vSAN cluster, when the "Ensure Accessibility" maintenance mode option is selected and one host is taken down, data remains accessible but not fully protected. If another host loses network connectivity afterward, it disrupts the cluster's redundancy mechanisms. Without access to all replicas or a quorum, the VMs might not be able to access their data properly, causing potential data loss. Therefore, in this scenario, VMs might experience data loss due to the insufficient number of hosts to maintain data integrity.
A: Since only "Ensure Accessibility" has been selected VM objects are not rebuilt and could lose more object and get inaccesible, alos see: https://docs.vmware.com/en/VMware-vSphere/8.0/vsan-administration/GUID-521EA4BC-E411-47D4-899A-5E0264469866.html
Typically, only partial data evacuation is required. However, the virtual machine might no longer be fully compliant to a VM storage policy during evacuation. That means, it might not have access to all its replicas. If a failure occurs while the host is in maintenance mode and the Primary level of failures to tolerate is set to 1, you might experience data loss in the cluster Answer A https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.vsphere.virtualsan.doc/GUID-521EA4BC-E411-47D4-899A-5E0264469866.html
A. VMs might experience data loss. The "Ensure Accessibility" option is designed to tolerate the loss of one host in maintenance mode, but when a second host loses network connectivity, it can disrupt the normal operation of the vSAN cluster. In the worst-case scenario, VMs may not be able to access their data, which could lead to data unavailability and potential data loss.
Answer A : once the first host is in maintenance, some objects are accessible but not protected, and others are fully protected (if they have no components on the host). Once another host fails, some objects will only lose their witness or one copy of the data, and the ones which where not protected anymore will lose their data until at least one host come back to business.
B is correct as default policy would be RAID 1 mirror so with one host down that would leave 3 hosts then if one more host failed that would leave 2 of 4”3 objects available for each vm which is more than 50% of votes so VMs would then be on RAID 0 from one copy of data so still online and ok but with reduced redundancy
the question states 'ensure accessibility' has been selected, so some VMs could be located on the esxi hosts that fails when suddenly loses network connectivity. Therefore some VMs might experience data loss
The question is "How will the cluster be affected?" Correct it's B
When an administrator selects the “Ensure Accessibility” maintenance mode option in a vSAN cluster, vSAN ensures that all accessible virtual machines on the host remain accessible 1. Therefore, in this scenario, the virtual machines running on the host that is down for firmware upgrade will remain accessible. However, the virtual machines running on the host that has lost network connectivity to the remaining hosts may become inaccessible until the network connectivity is restored 12.
Not correct : you may lose some VMs, but not ALL the VMs as stated in answer C.
A is correct: Typically, only partial data evacuation is required. However, the virtual machine might no longer be fully compliant to a VM storage policy during evacuation. That means, it might not have access to all its replicas. If a failure occurs while the host is in maintenance mode and the Failures to tolerate is set to 1, you might experience data loss in the cluster
A - If a failure occurs while the host is in maintenance mode and the Primary level of failures to tolerate is set to 1, you might experience data loss in the cluster. https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.vsphere.virtualsan.doc/GUID-521EA4BC-E411-47D4-899A-5E0264469866.html