What does 512e/4Kn mean in a hard-drive specification?

Question

While shopping for hard drives (in the range of 8TB to 12TB) to add to my file server (running Debian 10), I'm puzzled by the 512e/4Kn in the specs (for example, this Seagate model). My understanding is that 512e and 4Kn are mutually exclusive: 512e means the physical sectors are 4k but the drive presents itself and interfaces with the host as if its sectors were 512 bytes, whereas 4Kn means sectors are 4k, period.

Can someone shed some light on this? Please notice that my question is about the meaning of 512e/4Kn as opposed to 512e alone, or 4Kn alone.

BTW, I'm trying to achieve a 4Kn setup (last time I upgraded the machine, I got specifically 4Kn drives — and sure enough, fdisk -l /dev/sdX identifies them as physical sector size = 4096, logical sector size = 4096)

Answer 1

"512e/4Kn" stands for a internal, physical and real sector size of 4096 bytes. The n in 4Kn stands for "native". 512e means "512 bytes emulated". The emulated figure is what appears outside if operating systems and software is questioning the drive about its abilities.

The firmware of the hard drive then translates/emulates any 512 byte oriented command into something that fits into the real 4096 byte sector structure.

Example: The operating system wants to write 512 byte into the third sector of the disc (seen in units of 512 byte) (numbering starts at sector zero). As the disk really supports only 4096 bytes, the firmware will load the sector number zero (numbering starts at sector zero) (seen in units of 4096 byte) into a buffer. In a second step the firmware will put those 512 bytes at position 3x512 into the buffer. in the third and last step the firmware will rewrite the modified buffer of 4096 bytes back on disc into sector number zero.

Please read also:

Why do hard drives still use 512 bytes emulated sectors?

Update 5.9.2021 16:55 Berlin time

In response to the modification of your question I checked some Seagate spec sheets. They made the emulation from 4k native to 512 emulated switchable by the operating system and are marketing this ability as "FastFormat".

https://www.seagate.com/files/www-content/product-content/enterprise-performance-savvio-fam/enterprise-performance-15k-hdd/_cross-product/_shared/doc/seagate-fast-format-white-paper-04tp699-1-1701us.pdf