From: Eric Sandeen Subject: Re: [PATCH, RFC] mke2fs: get device topology values from blkid Date: Fri, 18 Sep 2009 09:23:47 -0500 Message-ID: <4AB397F3.3090206@redhat.com> References: <4AB2B6B9.7010506@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: ext4 development To: "Martin K. Petersen" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:27985 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751150AbZIROXw (ORCPT ); Fri, 18 Sep 2009 10:23:52 -0400 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: Martin K. Petersen wrote: >>>>>> "Eric" == Eric Sandeen writes: > > Eric> This is just a rough cut, due to the blkid header selection issues > Eric> I mentioned earlier on the list. It'll also need some config-fu > Eric> to be sure we've got a blkid which has these calls, but with it in > Eric> place, we'll finally have automatic selection of stride/stripe: > > What about alignment? > > I know that in our friendly DM universe the volume will be aligned. But > what if the user does mkfs on /dev/sdX and the drive isn't naturally > aligned? heh, mkfs.ext* complains if you point it at a whole disk, though it will proceed... > How flexible is the extN on-disk format? Can you pad and shift things > if need be? shifting by 63 sectors would be tough I think; maybe a stern warning and a "proceed y/N?" would be better. I had sort of assumed that -we- could assume the lower layers (partitions, volumes) got well-aligned before mkfs, but didn't think about making the fs on the whole device. > Also, are you guys affected by the previously-acked-sectors-are-now-gone > problems with 512-byte logical/4KB physical drives? previously-acked-sectors-are-now-gone? I guess I haven't been keeping up. What do you mean by this? -Eric