From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Greaves Subject: Re: linear raid space utilization Date: Sat, 21 Jan 2006 08:48:08 +0000 Message-ID: <43D1F548.6020407@dgreaves.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Andy Gajetzki Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Andy Gajetzki wrote: >Hi there, I recently had a disk go bad in a linear RAID built with >mdadm. The particular disk that failed was the last device of the >RAID. I am curious about how devices are utilized in a linear RAID. >Would the md be filled sequentially from device 1 upto 5? In other >words, what are the odds that the last disk was "empty" when it went >south? > >Thanks for your time, > > Linear raid does provide sequential blocks on disks 1...n So as long as the filesystem you used was something like 'dd of=/dev/md0' then you'd be OK However if you made a 'proper' filesystem on it then the disk usage would vary depending on whether it was ext2,ext3,xfs,jfs etc etc If the bad disk is totally gone then you're at the mercy of fs deign and fsck - otherwise try and use ddrescue to get an image of it (and the other disks). Make a 'safe' image and a 'working' image of the bad disk before attempting repair on 'working' images. (Of course you need lots of disk space so you may need new disks - depends how valuable your data is) HTH David --