Which is the block size on the VMFS6 datastore?

VMFS6 does not use 8MB as a uniform block size; 8MB was one of the configurable block size options available in the older VMFS3 file system.

VMFS6 does not use a single 1MB block size for all files regardless of size; large files use a larger 512MB block size.

VMFS6 does not use 512KB for small file blocks or 64MB for large file blocks; these values do not correspond to any documented VMFS6 specification.

VMFS6 distinguishes between small and large file block allocation, using 1MB blocks for small files such as configuration and metadata files. Large files, particularly large VMDK virtual disk files, use 512MB blocks to reduce the overhead of managing large numbers of small block allocations and improve performance at scale.