divac :
Yes, NTFS sets cluster size to 4kb. However, if the HDD interface is 512b, is it not going to be 'throttled'? If not, then in theory there is no performance difference between 4knative and 512emu in Win7?
No, there will be no performance difference.
Even if there were such as thing as a "true" 4KByte sector drive made today, there wouldn't be a performance difference. There's no difference between sending a commands that says:
- "write eight 512-byte sectors starting at LBN 123456" followed by 4Kbytes of data
or
- "write one 4096-byte sector starting at LBN 123456" followed by 4Kbytes of data
Both actions take one command, the command itself is the same size, and the amount of data transferred over the SATA connection is the same. So no performance difference is attributable to the difference between "native" 4K commands to a 4K drive versus 512-byte commands to a 4K drive emulating a 512-byte drive.
The reason for the 4K-byte sectors is to get more capacity per track, not because it's faster.
Mind you, because 4K sectors cram a little more data in each track, the data IS transferred a little faster than with 512-byte sectors (more data per track = more data transferred with each rotation of the platter). But that's true of ANY 4KByte/sector drive whether it emulates a 512-byte sector drive or not. The performance difference isn't about the commands used to transfer the data or the sector size that the OS thinks is being used, it's about the physical layout of data on the track.