From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ross Vandegrift Subject: Re: reconstructing raid5 with bad sectors Date: Mon, 4 Aug 2003 14:14:15 -0400 Sender: linux-raid-owner@vger.kernel.org Message-ID: <20030804181415.GA3575@willow.seitz.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: To: dean gaudet Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Mon, Aug 04, 2003 at 10:08:15AM -0700, dean gaudet wrote: > is there an offline tool which can reconstruct such an array? or even an > offline tool which already has the parity calculation code and such which > i could extend to support such reconstruction? > > i considered copying the two bad disks with "dd conv=noerror,sync", which > would stop the kernel from marking the drives as bad, but that seems a bit > less than ideal because i really would like to reconstruct the bad stripes > using the 3 valid copies and not include an all-zeroes copy created by dd. dd_rescue sounds like your friend - it'll let you make raw backups of the partitions, but instead of quitting on errors, it'll keep going until it passes the bad areas. You'll probably need a few disks to use as dd_rescue targets, but once you have images of the needed partitions, rebuild should work fine (assuming of course, that you're correct in saying the errors never overlap). -- Ross Vandegrift ross@willow.seitz.com A Pope has a Water Cannon. It is a Water Cannon. He fires Holy-Water from it. It is a Holy-Water Cannon. He Blesses it. It is a Holy Holy-Water Cannon. He Blesses the Hell out of it. It is a Wholly Holy Holy-Water Cannon. He has it pierced. It is a Holey Wholly Holy Holy-Water Cannon. He makes it official. It is a Canon Holey Wholly Holy Holy-Water Cannon. Batman and Robin arrive. He shoots them.