From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: Bad drive discovered during raid5 reshape Date: Tue, 30 Oct 2007 22:43:38 +1100 Message-ID: <18215.6378.912706.274201@notabene.brown> References: <47258776.9020601@sisna.com> <18214.53051.652280.492087@notabene.brown> <472712E5.10806@dgreaves.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from David Greaves on Tuesday October 30 Sender: linux-raid-owner@vger.kernel.org To: David Greaves Cc: Kyle Stuart , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Tuesday October 30, david@dgreaves.com wrote: > Neil Brown wrote: > > On Monday October 29, kstuart@sisna.com wrote: > >> Hi, > >> I bought two new hard drives to expand my raid array today and > >> unfortunately one of them appears to be bad. The problem didn't arise > > > Looks like you are in real trouble. Both the drives seem bad in some > > way. If it was just sdc that was failing it would have picked up > > after the "-Af", but when it tried, sdb gave errors. > > Humble enquiry.... :) > > I'm not sure that's right? > He *removed* sdb and sdc when the failure occurred so sdc would indeed be non-fresh. I'm not sure what point you are making here. In any case, remove two drives from a raid5 is always a bad thing. Part of the array was striped over 8 drives by this time. With only six still in the array, some data will be missing. > > The key question I think is: will md continue to grow an array even if it enters > degraded mode during the grow? > ie grow from a 6 drive array to a 7-of-8 degraded array? > > Technically I guess it should be able to. Yes, md can grow to a degraded array. If you get a single failure I would expect it to abort the growth process, then restart where it left off (after checking that that made sense). > > In which case should he be able to re-add /dev/sdc and allow md to retry the > grow? (possibly losing some data due to the sdc staleness) He only needs one of the two drives in there. I got the impression that both sdc and sdb had reported errors. If not, and sdc really seems OK, then "--assemble --force" listing all drives except sdb should make it all work again. NeilBrown