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SubjectRe: ATA support for 4k sector size
On Wed, Feb 25, 2009 at 09:50:43PM -0500, Theodore Tso wrote:
> On Wed, Feb 25, 2009 at 06:27:18PM -0500, Martin K. Petersen wrote:
> > Because of 63-sector legacy problems a bunch of ATA vendors will
> > initially ship 512/4096 drives that are not naturally aligned.
> > I.e. logical sector 63 will be aligned on a 4KB hardware sector
> > boundary to overcome the misaligned default partitioning.
> Are we *sure* that this is what they plan to be doing? Is there a way
> we can query the hardware to find out for sure what drives are doing
> what?

The drive I have that's pretending to be a 512/4k drive reports this:

$ sudo sg_readcap -l /dev/sdc
Read Capacity results:
Protection: prot_en=0, p_type=0
Last logical block address=625142447 (0x2542eaaf), Number of logical blocks=625142448
Logical block length=512 bytes
Logical blocks per physical block=3 (log base 2) [actual=8]
Lowest aligned logical block address=0
Device size: 320072933376 bytes, 305245.3 MiB, 320.07 GB

This disagrees with Martin's assertion.

Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."

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