From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Tran Subject: Re: Did --zero-superblock by mistake ... How can I get back data ? Date: Fri, 10 Mar 2006 13:38:19 -0600 Message-ID: <4411D5AB.2030609@us.ibm.com> References: <4411BF56.7010801@free.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4411BF56.7010801@free.fr> Sender: linux-raid-owner@vger.kernel.org To: Raphael Delaporte Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Raphael Delaporte wrote: > Hi, > > On a RAID 5 array which is composed by 5 hdd, I did mdadm > --zero-superblocks on each hdd because I thought it was required to > use the array on a new system.... > > But now, I cannot mdadm --assemble the array. It says : > > mdadm: no RAID superblock on /dev/sda > mdadm: /dev/sda has no superblock - assembly aborted > > Is it possible to assemble this array because I don't want to lose my > data... Someone told me that I can do a : > > mdadm -Cv /dev/md0 -l5 -n5 /dev/sda /dev/sdb /dev/sdc /dev/sdd /dev/hdc > > But if do that, all the data on the raid will be lost or not ? > > Is there an other way to get back these data ? > > Thank you very much for your help. > I would try to recreate the raid5 array with *1 missing disk,* then try to mount the array (read only) and verify the data. For example, mdadm -C /dev/md0 -l 5 -c 32 -p ls -n 5 /dev/sda /dev/sdb /dev/sdc /dev/sdd missing Notes: If you used /etc/mdadm.conf, specify the disk order on the ARRAY line with 1 missing disk to be safe. I specified the mdadm default chunk size (32K) and default parity algorithm (left-symmetric). You may have to use other values. You should change the order of the disks if your data is invalid. -- Regards, Mike T.