An architect is designing a VMware Cloud Foundation (VCF) Private Cloud for a customer.

RAID-6 with FTT=2 is the appropriate vSAN storage policy for Site A because it satisfies both requirements: tolerance of two simultaneous host failures and maximum storage efficiency.

In vSAN, Failures to Tolerate (FTT)=2 means that a storage object remains accessible after two concurrent failures within the applicable fault-domain model. Both RAID-1 FTT=2 and RAID-6 FTT=2 can provide this level of protection, but their capacity overhead differs significantly.

RAID-1 FTT=2 uses three mirrored copies of the data, resulting in approximately 3× raw-capacity consumption for the protected object. By comparison, RAID-6 FTT=2 uses erasure coding with dual parity, providing two-failure tolerance with substantially better usable-capacity efficiency.

Site A contains 16 ESX hosts , providing more than enough hosts/fault domains to support RAID-6 FTT=2 placement requirements. This makes erasure coding the preferred choice where the design explicitly prioritizes storage efficiency while maintaining dual-failure protection.

A and D provide only FTT=1 and therefore cannot tolerate two simultaneous host failures. B provides the required resilience but consumes considerably more storage capacity than RAID-6.

Study Guide References/Topics: vSAN Storage Policy-Based Management; Failures to Tolerate; RAID-1 Mirroring; RAID-5/RAID-6 Erasure Coding; Capacity Efficiency; vSAN Cluster Sizing and Fault Domains.