From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: RAID-5 spare drive: Can't make spare persist across reboot Date: Sun, 31 May 2009 07:53:50 +1000 Message-ID: <18977.43758.674932.381022@notabene.brown> References: <984c80610905301137l7649391fg64a8108769abd216@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from David Rea on Saturday May 30 Sender: linux-raid-owner@vger.kernel.org To: David Rea Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Saturday May 30, dave@daverea.com wrote: > [First-time poster, done plenty of googling and archive searching > before sending this, so if it's already been covered my apologies in > advance...] > > Hello All- > > I am running a 3-disk RAID-5 using kernel 2.6.24 and mdadm 2.6.3 under > Ubuntu server 8.04LTS. I'm trying to add a spare drive to the array. > > /dev/md0 == /dev/sdc, /dev/sdd, /dev/sda > > I want to add /dev/sdb1 as a spare partition, so I tried `mdadm > /dev/md0 --add /dev/sdb1` ... this worked great; running `mdadm > --detail /dev/md0` shows 3 active and 1 spare. Cool! > > However, after a reboot, I'm back to 3 active and 0 spare drives. I > tried adding the spare to my DEVICES list in /etc/mdadm/mdadm.conf, > and adding a SPARES=1 attribute to the ARRAY line in that file, still > no persistence. I tried running `update-initramfs -u` after changing > mdadm.conf (per an IRC suggestion) but still no persistence. This should "just work". There might be some hints in /var/log/messages if you'd like to post that. > > -- Is it possible to do what I'm trying to do? Definitely. > -- Do I need to create the array anew using `mdadm --create` and > specifying "--spare-devices=1 /dev/sdb1" during creation? No. > -- Will creating the array again risk corrupting the data already present? There is always a risk - you might type the wrong command by mistake. Other than that there is no risk. However doing so won't gain you anything. > -- Is there any way to instantiate a superblock on /dev/sdb1 so that > it can be associated with this array's UUID? You have already done that. Use mdadm --examine /dev/sdb to confirm. > -- I have the ARRAY line (in mdadm.conf) specified by UUID; could this > be causing the spare to be excluded, since it (presumably) does not > have a superblock? No. And it does have a superblock. NeilBrown