From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: reshape from raid5 to raid6 failed -- and backup file is gone? Date: Fri, 23 Apr 2010 08:37:01 +1000 Message-ID: <20100423083701.5fa5da72@notabene.brown> References: <20100423080938.5ef90287@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Rich Rauenzahn Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Thu, 22 Apr 2010 15:26:13 -0700 Rich Rauenzahn wrote: > > > > > > It is very odd that the backup file disappeared. =C2=A0What is > > =C2=A0 /.MEDIA/tmp > > ?? Not a tmpfs filesystem I hope... >=20 > No, a persistent filesystem on another disk -- with no autodelete > scripts or anything. Very very weird that it disappeared. I saw it > before I went to bed... was about 50MB if I recall. Unless the fsck > at boot removed it -- but I would imagine you make sure you fsync tha= t > file to disk before you proceed? I think ./.MEDIA is ext4. >=20 I don't fsync the directory containing the file, but I do fsync the fil= e quite regularly. But if the system ran for even just one minute after the --grow started= the directory would have been flushed to disk so the absence of an fsync on= the directory cannot have been a problem... not that I'm convinced it could= be a problem anyway. > > You could hack mdadm to assemble the array even without a backup fi= le. > > Get 'Grow_restart' to always return 0. > > > > Then most of your data should be assessible, but the could be a sec= tion in > > the middle which is currupt. >=20 > As long as fsck can bring it back to a consistent state, I'm ok with > that. But I would guess some file contents could be silently > corrupt? Yes, there could be silent corruption. Or there might be no corruption= =2E If the backup file was about 50MB (which seems likely) then the total a= mount of corruption should not exceed 50MB - though in an indexing block was = lost you could loose more than 50MB of a single file.. NeilBrown -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html