From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: Proper partition type for components with V1.x superblocks? Date: Mon, 07 Jul 2008 10:38:52 -0700 Message-ID: <487254AC.7040106@zytor.com> References: <484F9A3E.7020709@rabbit.us> <18512.25940.653867.623185@notabene.brown> <486BFB03.7060100@zytor.com> <1215062276.14196.6.camel@firewall.xsintricity.com> <18545.35548.800516.532854@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <18545.35548.800516.532854@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: Doug Ledford , Peter Rabbitson , linux-raid@vger.kernel.org List-Id: linux-raid.ids Neil Brown wrote: > > 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. > One more thing on this: this is actually fine as long as the RAID code detects the out-of-syncness. This can't be foolproof, of course, but for virtually all filesystems there is *something* in the first megabyte or so (usually within the first 128K) that is touched by almost every write -- the superblock, or its equivalent. If the RAID code did a sanity check on the first megabyte, it would catch the vast majority of all unintentional desynchronization events. -hpa