Good Post by Wade Holmes (thank you)
Recently a question came up around Virtual SAN and block alignment that I want to address. Traditionally, there have been two potential block alignment issues in vSphere environments:
1) VMFS block alignment with respect to underlying array chunks. Alignment at the VMFS layer has been addressed since VMFS-3 (used in vSphere 3 and 4) being aligned at Logical Block Address (LBA) 128 and VMFS-5 (used in vSphere 5.x) being aligned at LBA 2048 by default.
Read on here