From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Tokarev Subject: Re: Time to deprecate old RAID formats? Date: Sat, 20 Oct 2007 18:09:06 +0400 Message-ID: <471A0C02.4030407@msgid.tls.msk.ru> References: <18200.49267.763509.924873@stoffel.org> <18200.53593.687483.120827@stoffel.org> <1192810534.1666.68.camel@firewall.xsintricity.com> Mime-Version: 1.0 Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1192810534.1666.68.camel@firewall.xsintricity.com> Sender: linux-raid-owner@vger.kernel.org To: Doug Ledford Cc: John Stoffel , Justin Piszcz , linux-raid@vger.kernel.org List-Id: linux-raid.ids Doug Ledford wrote: [] > 1.0, 1.1, and 1.2 are the same format, just in different positions on > the disk. Of the three, the 1.1 format is the safest to use since it > won't allow you to accidentally have some sort of metadata between the > beginning of the disk and the raid superblock (such as an lvm2 > superblock), and hence whenever the raid array isn't up, you won't be > able to accidentally mount the lvm2 volumes, filesystem, etc. (In worse > case situations, I've seen lvm2 find a superblock on one RAID1 array > member when the RAID1 array was down, the system came up, you used the > system, the two copies of the raid array were made drastically > inconsistent, then at the next reboot, the situation that prevented the > RAID1 from starting was resolved, and it never know it failed to start > last time, and the two inconsistent members we put back into a clean > array). So, deprecating any of these is not really helpful. And you > need to keep the old 0.90 format around for back compatibility with > thousands of existing raid arrays. Well, I strongly, completely disagree. You described a real-world situation, and that's unfortunate, BUT: for at least raid1, there ARE cases, pretty valid ones, when one NEEDS to mount the filesystem without bringing up raid. Raid1 allows that. /mjt