Hi @Ashun ,
- Traditional block size advertised by hard disks is 512 bytes.
- NetApp LUNs use a larger block size to store data while continuing to advertise smaller 512 byte blocks to the host for compatibility purposes.
- Advertised blocks are referred to as logical blocks and underlying storage block is referred to as a physical block.
- NetApp LUN stores data in 4 KB physical blocks, which yields eight 512 byte logical blocks per physical block.
Reference: https://kb.netapp.com/on-prem/ontap/da/SAN/SAN-KBs/How_to_identify_unaligned_IO_on_LUNs