Explanation
The correct answer is A, the disk group must be deleted on each physical host in the vSAN OSA cluster to use the NVMe device. This is because vSAN OSA uses a disk group configuration where one disk is designated as a cache disk and the rest are capacity disks. To replace the cache disk with a different type or size, the disk group must be deleted first, which will erase all data on the disks and trigger a resynchronization of the affected objects. The administrator should put the host in maintenance mode and choose the option to evacuate all data before deleting the disk group. After replacing the cache disk with the NVMe device, the administrator should recreate the disk group and exit maintenance mode. The other options are incorrect for the following reasons:
B, the disk group does not need to be removed before adding new cache, is incorrect because adding a new cache disk to an existing disk group is not supported in vSAN OSA. The cache disk can only be replaced by deleting and recreating the disk group.
C, the host must be removed from vSAN OSA cluster before changing cache devices, is incorrect because removing the host from the cluster is not necessary and will cause more disruption and data loss than putting the host in maintenance mode. Removing the host will also delete its disk groups and require re-adding them after rejoining the cluster.
D, the cache disk drives must have a larger capacity, is incorrect because there is no requirement for the cache disk to have a larger capacity than the existing one. The cache disk size should be determined by the workload characteristics and performance requirements, not by the expansion process. References:
VMware vSAN Specialist v2 Exam Preparation Guide, page 10