Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758910AbYBLPFF (ORCPT ); Tue, 12 Feb 2008 10:05:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756431AbYBLPEy (ORCPT ); Tue, 12 Feb 2008 10:04:54 -0500 Received: from sovereign.computergmbh.de ([85.214.69.204]:36529 "EHLO sovereign.computergmbh.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756057AbYBLPEx (ORCPT ); Tue, 12 Feb 2008 10:04:53 -0500 Date: Tue, 12 Feb 2008 16:04:52 +0100 (CET) From: Jan Engelhardt To: Chris Mason cc: David Miller , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, btrfs-devel@oss.oracle.com Subject: Re: BTRFS partition usage... In-Reply-To: <200802120935.20437.chris.mason@oracle.com> Message-ID: References: <200802061200.14690.chris.mason@oracle.com> <200802120908.59602.chris.mason@oracle.com> <200802120935.20437.chris.mason@oracle.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1576 Lines: 35 > On Feb 12 2008 09:35, Chris Mason wrote: >> >> and slap the bootloader into "MBR", just like on x86. >> Or I am missing something.. > >It was a request from hpa, and he clearly had something in mind. He kindly >offered to review the disk format for bootloaders and other lower level >issues but I asked him to wait until I firm it up a bit. > >From my point of view, 0 is a bad idea because it is very likely to conflict >with other things. There are lots of things in the FS that need deep >thought,and the perfect system to fully use the first 64k of a 1TB filesystem >isn't quite at the top of my list right now ;) > >Regardless of offset, it is a good idea to mop up previous filesystems where >possible, and a very good idea to align things on some sector boundary. Even >going 1MB in wouldn't be a horrible idea to align with erasure blocks on SSD. I still don't like the idea of btrfs trying to be smarter than a user who can partition up his system according to (a) his likes (b) system or hardware requirements or recommendations to align the superblock to a specific location. 1MB alignment does not always mean 1MB alignment. Sector 1 begins at 0x7e00 on x86. And with the maximum CHS geometry (255/63), partitions begin at 0x7e00+n*8225280 bytes, so the SB is unlikely to ever be on a 1048576 boundary. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/