From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: Proper partition type for components with V1.x superblocks? Date: Mon, 7 Jul 2008 13:17:48 +1000 Message-ID: <18545.35548.800516.532854@notabene.brown> References: <484F9A3E.7020709@rabbit.us> <18512.25940.653867.623185@notabene.brown> <486BFB03.7060100@zytor.com> <1215062276.14196.6.camel@firewall.xsintricity.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from Doug Ledford on Thursday July 3 Sender: linux-raid-owner@vger.kernel.org To: Doug Ledford Cc: "H. Peter Anvin" , Peter Rabbitson , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Thursday July 3, dledford@redhat.com wrote: > On Wed, 2008-07-02 at 15:02 -0700, H. Peter Anvin wrote: > > > > Why 0xDA? > > > > As far as I know, the closest thing there is to a registry is the list > > that aeb at least used to maintain. Yes. http://www.win.tue.nl/~aeb/partitions/partition_types-1.html lists 0xDA as da Non-FS Data Added on request of John Hardin (johnh@aproposretail.com). which is the closest we could come to "you won't want to look at or do anything to this partition". > > Actually, if you are going to use version 1 superblocks anyway, then > just list the partitions as normal linux partitions. The whole > linux-raid-autodetect partition type was originally only for auto detect > at bootup. If you weren't using that feature, then standard linux type > was good enough. And if you use version 1.1 or 1.2 superblocks, then > you really don't have anything to worry about since the location of the > superblock and the data start offset means that the partition won't get > accidentally recognized as a non-raid partition. But if you use 1.0, then some well-meaning install program might mount one drive from a raid1 as a filesystem, write to it, and get your RAID all out of sync. The whole point of this exercise was to find a way to make sure code that took the partition type to mean something didn't make the wrong decision. 0xDA seems the best answer for that. NeilBrown