Indranil,  I believe this VMware knowledge base article has the information you are requesting: [URL]   Here is some of the information from the KB: What are 4K Native and 512e drives?Industry standard disk drives have been using a native 512 bytes sector size. However, due to the increasing demand for larger capacities, the storage industry introduced new advanced formats, which are 512-byte emulation (512e) and 4KB Native (4Kn). 4Kn is the advanced format in which the physical sectors and logical sectors are both 4,096 bytes in size. 512e is the advanced format in which the physical sector size is 4,096 bytes, but the logical sector size emulates 512 bytes sector size. This table compares Native 512-byte sectors to the new advanced formats: Format Logical Sector Size Physical Sector Size 512n 512 512 512e 512 4,096 4Kn 4,096 4,096   Does current GA version of vSphere and VSAN support 4K Native drives? 4K Native drives are not supported in current GA releases of vSphere and VSAN.    Does current GA version of vSphere and VSAN support 512e drives?   512e drives are not supported with the current versions of vSphere and VSAN due to potential performance issues when using these drives.  
 In one of the test in the lab using ESX 5.5 connected to an XtremIO running XIOS 3.0, VM with OEL 6.3 was created and mapped with the LUNs from the XtremIO as Physical RDMs. When the VM was being started  , we got an error message “38 – Function Not Implemented”  But if we convert the same LUNs to E512 mode (emulated 512-byte sectors) the VM will start fine. Can anybody throw some light whether it will be possible to access Native 4K Sector LUNs on ESX 5.5?
Compatibility of ESX 5.5 with XtremIO release 3.0