From mboxrd@z Thu Jan 1 00:00:00 1970 From: Giovanni Tessore Subject: Re: Linux mdadm superblock question. Date: Sat, 13 Feb 2010 11:06:17 +0100 Message-ID: <4B767999.1070902@texsoft.it> References: <4B7664AC.4080504@texsoft.it> <4877c76c1002130126m7ff93c33m5159eb4e554d22b4@mail.gmail.com> <4B767249.2070305@texsoft.it> <4877c76c1002130140x65cb2b24ydcb57913c6d89b64@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4877c76c1002130140x65cb2b24ydcb57913c6d89b64@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids >>>> I recently reinstalled my systems, and I had to use superblock 0.9 to be >>>> able to boot ext4 from raid-1 (kernel 2.6.31 - grub2 1.97-beta4). >>>> I didn't go deep with it as I was quite in hurry, so I'm not sure if it >>>> depends by grub2 or by kernel's md autodetection at boot. >>>> I used superblock 1.1 for the others md devices. >>>> >>> mdadm 1.0 block devices, since stored at the end, can still be used >>> /read only/ the same way that 0.90 devices were used before grub knew >>> how to talk to them. By looking at the underlying block devices and >>> ignoring their tails. This does however only hold for raid-1 layouts >>> with the 1.0 or 0.90 format labels. >>> >> I guessed so, infact I created superblock 1.0 for the raid-1 devices md0 >> (root) and md1 (swap), while 1.1 for the others .. but it didn't work and I >> had to revert to 0.9 for root and swap ... >> >> > > Just a guess, but did you tell grub root was /dev/md0 or did you say > root was /dev/sd(whatever backs md0) ? > Root was set to (md0), I followed the installer of the distro (ubuntu 9.10 srv) and also tried manually with update-grub and then grub-install /dev/sda, grub-install /dev/sdb, grub-install /dev/sdc (3 disk raid-1) Both failed with superblock 1.0, giving a message like 'missing mapping of device /dev/md0', infact into /boot/grub/device.map it was missing (even for 0.9), but also adding it ( (md0) /dev/md0 )didn't help, giving other error messages. Btw, even if I missed something, the point is: - with 0.9 it worked painless - with 1.0 it didn't work donno if it dependes by distro, kernel of md, but some different behaviour relative to superblock 0.9 and 1.0 existed. I didn't investigate further as I was in extreme hurry to setup the system. Regards -- Cordiali saluti. Yours faithfully. Giovanni Tessore