From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 22 Jan 2001 18:29:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 22 Jan 2001 18:29:28 -0500 Received: from postfix.conectiva.com.br ([200.250.58.155]:15111 "HELO postfix.conectiva.com.br") by vger.kernel.org with SMTP id ; Mon, 22 Jan 2001 18:29:12 -0500 Message-ID: <3A6CC21B.D4ABE21C@conectiva.com.br> Date: Mon, 22 Jan 2001 21:28:27 -0200 From: Andrew Clausen Organization: Conectiva X-Mailer: Mozilla 4.76 [pt_BR] (X11; U; Linux 2.2.17-14cl i586) X-Accept-Language: en MIME-Version: 1.0 To: Russell King Cc: linux-fsdevel@vger.kernel.org, bug-parted@gnu.org, linux-kernel@vger.kernel.org Subject: Re: Partition IDs in the New World TM In-Reply-To: <200101222242.WAA00893@raistlin.arm.linux.org.uk> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Russell King wrote: > > Andrew Clausen writes: > > Why is this necessary? Can't the RAID drivers probe the device for > > signatures, the same way file systems do? > > One possible problem I can see here is to do with removal of RAID. Think > of a RAID-1 array (2 or more disks containing identical data). The > partition can be validly identified as an ext2 filesystem. But wait, it > has a RAID superblock at the end. > > How do we know if this superblock is current or not? After all, a mke2fs > on the device won't remove it. Yes, you could fill the partition with > zeros and start again, or you could just change the partition ID. Yeah, this is a big problem. Parted solves it, by defining a clobber() operation for each file system type (which can/should be extended to RAID, if/when we get around to supporting it properly). clobber() removes all signatures. So, I guess the short answer is: mke2fs should remove the RAID super. For those of you who don't like all-in-one libraries like libparted - not mentioning any Christo^Wnames - you could probably have clobber.ext2, etc. However, you would want to have a comprehensive set of clobber.*. Fortunately, clobber.X is going to be very small, so this should be a problem. So, the alternative is to define a RAID partition "data" type. (And forget about IDs for file systems) Andrew Clausen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/