[parted-devel] 4K sector and alignment support?

[Jeff Garzik]

Greetings from your friendly neighborhood SATA kernel hacker!

Drive companies like Seagate and Western Digital are beginning to poke 
me about 1K and 4K sector support.

Specifically, they are referring to drives that will have a 1K or 4K 
_physical_ sector size, yet still present the same old 512-byte sector 
size to the ATA driver and OS.

The main need is 1K and 4K sector _alignment_ support.  Does parted 
already have this?

Future ATA drives can be odd-aligned or even-aligned.

Even-aligned 1K drives writing 1K of data at sector #100 will (in "disk 
pseudocode") do:

	* seek to LBA 100
	* write data to LBA 100-101

Odd-aligned 1K drives writing 1K of data at sector #100 will do:

	* seek to LBA 99
	* read LBA 99-102
	* update data from internal buffer
	* write data to LBA 99-102

The latter is called a "read-modify-write cycle," and its a performance 
killer.

Therefore, it is critical that partition alignment matches internal ATA 
disk sector alignment, when these 1K and 4K drives come out.

	Jeff, your friendly local SATA hacker