From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Beck Subject: Re: Data Offset Date: Mon, 04 Jun 2012 20:26:05 +0200 Message-ID: <4FCCFDBB.201@pierre-beck.de> References: <20120602095237.3822e2c2@notabene.brown> <20120604133526.6da3bf10@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120604133526.6da3bf10@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: freeone3000 , linux-raid@vger.kernel.org List-Id: linux-raid.ids I'll try and clear up some confusion (I was in IRC with freeone3000). /dev/sdf is an empty drive, a replacement for a failed drive. The Array attempted to assemble, but failed and reported one drive as spare. This is the moment we saved the --examines. In expectation of a lost write due to drive write-cache, we executed --assemble --force, which kicked another drive. @James: remove /dev/sdf for now and replace /dev/sde3, which indeed has a very outdated update time, with the non-present drive. Post an --examine of that drive. It should report update time Jun 1st. We tried to re-create the array with --assume-clean. But mdadm chose a different data offset for the drives. A re-create with proper data offset will be necessary. Greetings, Pierre Beck Am 04.06.2012 05:35, schrieb NeilBrown: > On Fri, 1 Jun 2012 19:48:41 -0500 freeone3000 wrote: > >> Sorry. >> >> /dev/sde fell out of the array, so I replaced the physical drive with >> what is now /dev/sdf. udev may have relabelled the drive - smartctl >> states that the drive that is now /dev/sde works fine. >> /dev/sdf is a new drive. /dev/sdf has a single, whole-disk partition >> with type marked as raid. It is physically larger than the others. >> >> /dev/sdf1 doesn't have a mdadm superblock. /dev/sdf seems to, so I >> gave output of that device instead of /dev/sdf1, despite the >> partition. Whole-drive RAID is fine, if it gets it working. >> >> What I'm attempting to do is rebuild the RAID from the data from the >> other four drives, and bring the RAID back up without losing any of >> the data. /dev/sdb3, /dev/sdc3, /dev/sdd3, and what is now /dev/sde3 >> should be used to rebuild the array, with /dev/sdf as a new drive. If >> I can get the array back up with all my data and all five drives in >> use, I'll be very happy. > You appear to have 3 devices that are happy: > sdc3 is device 0 data-offset 2048 > sdb3 is device 1 data-offset 2048 > sdd3 is device 3 data-offset 1024 > > nothing claims to be device 2 or 4. > > sde3 looks like it was last in the array on 23rd May, a little over > a week before your report. Could that have been when "sde fell out of the > array" ?? > Is it possible that you replaced the wrong device? > Or is it possible the the array was degraded when sde "fell out" resulting > in data loss? > > I need more precise history to understand what happened, as I cannot suggest > a fixed until I have that understanding. > > When did the array fail? > How certain are you that you replaced the correct device? > Can you examine the drive that you removed and see what it says? > Are you certain that the array wasn't already degraded? > > NeilBrown >