From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Subject: Re: [dm-devel] Re: [PATCH 1/3] block: add alt_size Date: Mon, 11 May 2009 09:45:34 -0400 Message-ID: <20090511134534.GA32678@mars.virtualiron.com> References: <1241828002-12742-1-git-send-email-tj@kernel.org> <1241828002-12742-2-git-send-email-tj@kernel.org> <4A058D5C.6030206@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4A058D5C.6030206@kernel.org> Sender: linux-ide-owner@vger.kernel.org To: device-mapper development , tj@kernel.org Cc: Kay Sievers , jeff@garzik.org, linux-scsi@vger.kernel.org, Mauelshagen@redhat.com, linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, jens.axboe@oracle.com, martin.petersen@oracle.com List-Id: linux-scsi@vger.kernel.org .. 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: 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?