Re: ATA support for 4k sector size

[Matthew Wilcox]

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
Hence:
   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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