From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: recovering from raid5 corruption Date: Mon, 30 Apr 2012 08:52:57 +1000 Message-ID: <20120430085257.65d19c20@notabene.brown> References: <4F9DC2E5.1090509@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/XXwT8kmD2v3+fHYtpw=RXiy"; protocol="application/pgp-signature" Return-path: In-Reply-To: <4F9DC2E5.1090509@gmail.com> Sender: linux-raid-owner@vger.kernel.org To: Shaya Potter Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/XXwT8kmD2v3+fHYtpw=RXiy Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Sun, 29 Apr 2012 18:38:29 -0400 Shaya Potter wrote: > somehow my raid5 got corrupted in the contexts of a main disk failure=20 > (which wasn't raid related). >=20 > compounding this issue was that I had already had one disk in the raid5=20 > go bad and was in the process of getting it replaced. >=20 > this raid array was 5 disks. >=20 > What I mean by corrupted is that the superblock of 3 of the remaining 4=20 > devices seemed to have been wiped out (i.e. had a UUID of all 0s, though= =20 > still enough that it knew it was part of an md device) >=20 > now, the one whose superblock seems fine, places it at position disk 3=20 > (of 0-4) and the missing disk at disk 2. >=20 > this would imply that there are only 6 permutations possible for the=20 > other 3 disks. (even if that assumptions is wrong, there are only 120=20 > permutations possible, which I should easily be able to iterate over). >=20 > further compounding this, is that there were 2 LVM logical disks on the=20 > physical raid device. >=20 > I've tried being cute and trying all 6 permutations to force recreate=20 > the array, but lvm isn't picking up anything. (pvscan/lvscan/lvmdiskscan) >=20 > The original raid had a version of 0.90.00 (created in 2008), while the=20 > new one has a version 1.20. >=20 > have I ruined any chances of recovery by shooting in the dark with my=20 > cute attempts, am I SOL or is there a better/proper way I can try to=20 > recover this data? >=20 > Luckily for me, I've been on a backup binge of late, but there still=20 > about 500-1TB of stuff that wasn't backed up. You've written a new superblock 4K in to each device, where previously here was something. So you have probably corrupted something though we cannot easily tell what. Retry your experiment with --metadata=3D0.90. Hopefully one of those combinations will work better. If it does, make a backup of the data you want to keep, then I would suggest rebuilding the array from scratch. NeilBrown --Sig_/XXwT8kmD2v3+fHYtpw=RXiy Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBT53GSTnsnt1WYoG5AQJIdhAAnY8ISVShscY36x3l9Ov8Sm5sOFjGqSeC 0wDGrvhqFrQd0ritJrORbhjTZAV6BqkznHAQLcG57UN/72rEcxMkSnaLfxpRX+H4 wMVLhktNyuFMhXyMlGrgx4dcXh/AHX+mCxvx6Eb562tF7PY9BcKyiR2k672+mCeQ pKpb8YO/WLwWj+A7BbU+T+O3ov66l3j3eotY/0dlRLt8boNkWQZrNSMwZ8CA5ejP V2dH3cBQTcAwQsOvEth7khwUghk2VK0woorIn3OYx1UTCAlsO58KtwAl9r2PoTXc 7IVoKBzxlxUGMAD0DNetn658vnKoZMV8zFJqBmRaWGWiBV3WBhj/vmWin8ncSG2M vgJCKEbfw0LHbrTrP5gFeK6xznLFJ8ZYSYFcswLC32q2DDNgpPeWC2bbjDeN40iY Sv1MvwMblw0grhg1SgtiefC1Q3C/BGfE0zBd7mvJ9iN8I70/mqUQVnPfr18gPvLT Tc84tQCyQb/Ft5O32EgQ9zBdooeosMM/t2Lw7z/YFwv6qZxNzg8uUjYigpumM/FW bow244WIESGsFDtClc9VpgMqIPQcOAA6s8kQXbAZwZxfh/UOoJLnC9M7z3GukPWm EDg9YmGsGk5AwoNif+6ntphcZ2gv/xCQ40JlVYjPxRYwnMEszRDDdrlvlOAazkvV 8qYaq/8J2MM= =SK60 -----END PGP SIGNATURE----- --Sig_/XXwT8kmD2v3+fHYtpw=RXiy--