From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q160BSb5087093 for ; Sun, 5 Feb 2012 18:11:28 -0600 Received: from ipmail04.adl6.internode.on.net (ipmail04.adl6.internode.on.net [150.101.137.141]) by cuda.sgi.com with ESMTP id quboVgjKKgKEVEfF for ; Sun, 05 Feb 2012 16:11:26 -0800 (PST) Date: Mon, 6 Feb 2012 11:11:23 +1100 From: Dave Chinner Subject: Re: Placing the root partition on an XFS filesystem is not supported Message-ID: <20120206001123.GJ6922@dastard> References: <4F2B02C4.8070903@sandeen.net> <4F2C2C69.5020103@sandeen.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4F2C2C69.5020103@sandeen.net> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Eric Sandeen Cc: linux-xfs@oss.sgi.com, Marcos Mello On Fri, Feb 03, 2012 at 12:50:17PM -0600, Eric Sandeen wrote: > On 2/3/12 8:39 AM, Marcos Mello wrote: > > Eric Sandeen sandeen.net> writes: > > > >> > >> In general there is no problem with xfs on a root partition. However, the > > installer > >> may not make it easy or available for you. > >> > >> (I never use xfs for /boot though, I don't trust grub enough for that > > honestly). > >> > >> -Eric > > > > Same thing on Fedora 16. Let's hope some day Anaconda will change that. > > F16 prevents it? I didn't see it in the upstream tree. That should > not be so. :/ > > > About GRUB with a XFS /boot the problem was with GRUB Lagacy, wasn't it? > > Or GRUB2 is still buggy? > > I have no idea, actually. I delved into grub a bit, it was disturbing > enough that I have not tried to look at grub2. :) Certainly the problem exists with legacy grub - it assumes that it can write to the first sector or any disk or partition which overwrites the XFS superblock... The grub2 manual: http://www.gnu.org/software/grub/manual/grub.html#BIOS-installation indicates that if you are using BIOS/MBR based booting, then grub2 still writes to the first sector of the partition that contains the grub directory to install the stage 1.5 loader. Indeed: "boot.img On PC BIOS systems, this image is the first part of GRUB to start. It is written to a master boot record (MBR) or to the boot sector of a partition. Because a PC boot sector is 512 bytes, the size of this image is exactly 512 bytes. The sole function of boot.img is to read the first sector of the core image from a local disk and jump to it. Because of the size restriction, boot.img cannot understand any file system structure, so grub-setup hardcodes the location of the first sector of the core image into boot.img when installing GRUB. " IOWs, you have to treat grub2 identically to legacy grub in that it thinks it owns the first sector of any partition on the disk. Therefore, you need a separate /boot partition that is not formated with XFS to be safe. There's a reason I went back to using LILO.... Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs