[dm-devel] Re: [PATCH 1/3] block: add alt_size

Konrad Rzeszutek konrad at virtualiron.com
Mon May 11 13:45:34 UTC 2009


.. snip ..
> > Also, values with magic block counts, while there is no way to get the
> > blocksize with the same interface, are pretty weird. I think the
> > current "size" attribute is just a bug.
> 
> Logical block size is fixed at 512 bytes.  Offset and size are always
> represented in multiples of 512 bytes and only get converted to
> hardware block size in the lld.

That interpretation is at odds with the work that Martin Peterson is
doing with the 4K support. In the e-mail titled: "Re: [PATCH 4 of 8] sd:
Physical block size and alignment support",
Message-ID:<yq1ab67b51p.fsf at sermon.lab.mkp.net> he says:

"
	Konrad> about what a 'logical block', and 'physical block' is
	Konrad> vs. 'hardware sector' ?

	Well, another item on my todo list is to kill the notion of hardware
	sector completely.  The protocols have been referring to logical blocks
	for ages.

	It hasn't been a big problem until now because logical block size has
	been equal to the hardware sector size.  That's no longer a valid
	assumption.
"

Are the ATA/SCSI/etc specs at odds with each other about this?




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