From mboxrd@z Thu Jan  1 00:00:00 1970
From: NeilBrown <neilb@suse.de>
Subject: Re: recovering from raid5 corruption
Date: Mon, 30 Apr 2012 09:44:10 +1000
Message-ID: <20120430094410.6d49a8e9@notabene.brown>
References: <4F9DC2E5.1090509@gmail.com>
	<20120430085257.65d19c20@notabene.brown>
	<4F9DCEC6.1050109@gmail.com>
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To: Shaya Potter <spotter@gmail.com>
Cc: linux-raid@vger.kernel.org
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On Sun, 29 Apr 2012 19:29:10 -0400 Shaya Potter <spotter@gmail.com> wrote:

> On 04/29/2012 06:52 PM, NeilBrown wrote:
> >
> > You've written a new superblock 4K in to each device, where previously =
here
> > was something.   So you have probably corrupted something though we can=
not
> > 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 y=
ou
> > want to keep, then I would suggest rebuilding the array from scratch.
>=20
> ok, thanks, that was a huge help.
>=20
> I have it setup correctly now (obvious due to the fact that I can read=20
> the lvm configuration without any gibberish when ordered correctly).
>=20
> however, now I need to figure out how to recreate the lvm appropriately.=
=20
>   I see the configuration "file" in at the start of the raid array (less=
=20
> -f /dev/md0 which I'm including below)
>=20
> I asusme there should be a way to reuse this data to recreate the lvm?
>=20
> any continued advice would be appreciated, googling doesn't seem to come=
=20
> up with much if one doesn't have a backup of the lvm data.

I don't use LVM myself so I don't know all the details, but doesn't 'pvscan'
find them?  I don't know what you do after that.

NeilBrown


>=20
> raid5 {
> id =3D "8r27WQ-HvIw-0RQV-aksr-LJGN-DLVD-1WBg8h"
> seqno =3D 6
> status =3D ["RESIZEABLE", "READ", "WRITE"]
> extent_size =3D 8192
> max_lv =3D 0
> max_pv =3D 0
>=20
> physical_volumes {
>=20
> pv0 {
> id =3D "7P0W3p-XoPg-rCo8-HJ2G-Hfxc-UDWI-x6nQck"
> device =3D "/dev/md0"
>=20
> status =3D ["ALLOCATABLE"]
> dev_size =3D 11721107456
> pe_start =3D 384
> pe_count =3D 1430799
> }
> }
>=20
> logical_volumes {
>=20
> data {
> id =3D "YZvrHt-Glyr-wnj0-QzV1-qRe6-VcRH-D7wU3U"
> status =3D ["READ", "WRITE", "VISIBLE"]
> segment_count =3D 1
>=20
> segment1 {
> start_extent =3D 0
> extent_count =3D 524288
>=20
> type =3D "striped"
> stripe_count =3D 1        # linear
>=20
> stripes =3D [
> "pv0", 0
> ]
> }
> }
>=20
> image {
> id =3D "uHOzpc-l8L7-eF5h-Fa0C-EsCS-sM6X-3GpOP0"
> status =3D ["READ", "WRITE", "VISIBLE"]
> segment_count =3D 1
>=20
> segment1 {
> start_extent =3D 0
> extent_count =3D 906511
>=20
> type =3D "striped"
> stripe_count =3D 1        # linear
> stripes =3D [
> "pv0", 524288
> ]
> }
> }
> }
> }
> # Generated by LVM2 version 2.02.39 (2008-06-27): Wed Aug 19 23:36:50 2009
>=20
> contents =3D "Text Format Volume Group"
> version =3D 1
>=20
> description =3D ""
>=20
> creation_host =3D "nas"   # Linux nas 2.6.27-14-generic #1 SMP Fri Jul 24=
=20
> 22:19:33 UTC 2009 i686
> creation_time =3D 1250739410      # Wed Aug 19 23:36:50 2009


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