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From: "Rainer Fügenstein" <rfu@oudeis.org>
To: linux-lvm@redhat.com
Subject: Re: [linux-lvm] recover volume group & locical volumes from PV?
Date: Wed, 15 May 2019 18:55:37 +0200	[thread overview]
Message-ID: <61004ae8-c29d-1402-9674-39e882bca6c8@oudeis.org> (raw)
In-Reply-To: <6747eb8e-b15c-dfdd-610b-bc5143368a63@redhat.com>

hi,

I discovered that the lvm text files recovered from lost+found where out 
of date. I got as far as reconstructing such a lvm config file from data 
stored in the first MB, but after some syntax errors and values that 
didn't look consistent, I decided to do a re-install.

fortunately, didn't lose much data.

thank you both for your help, provided valuable insight.

cu


On 13/05/2019 10:37, Zdenek Kabelac wrote:
> Dne 12. 05. 19 v 0:52 "Rainer F�genstein" napsal(a):
>> hi,
>>
>> I am (was) using Fedora 28 installed in several LVs on /dev/sda5 (= PV),
>> where sda is a "big" SSD.
>>
>> by accident, I attached (via SATA hot swap bay) an old harddisk
>> (/dev/sdc1), which was used about 2 months temporarily to move the volume
>> group / logical volumes from the "old" SSD to the "new" SSD (pvadd,
>> pvmove, ...)
>>
> 
> Hi
> 
> I don't understand how this could have happened by accident.
> lvm2 provides strong detection of duplicated devices.
> It also detects older metadata.
> 
> So you would have to put in 'exact' but just old 'copy' of your device
> and at the same time drop out the original one -� is that what you've 
> made ??
> 
>> this combination of old PV and new PV messed up the filesystems. when I
>> noticed the mistake, I did a shutdown and physically removed /dev/sdc.
>> this also removed VG and LVs on /dev/sda5, causing the system crash on
>> boot.
>>
>>
>> [root@localhost-live ~]# pvs
>> �� PV�������� VG������������� Fmt� Attr PSize��� PFree
>> �� /dev/sda5����������������� lvm2 ---�� <47.30g <47.30g
>> �� /dev/sdc1� fedora_sh64���� lvm2 a--� <298.09g 273.30g
>>
>> is there any chance to get VG and LVs back?
> 
> 
> VG & LV are just 'terms' - there is no 'physical-content' behind them - 
> so if you've already used your filesystem and modified it's bits on a 
> device - the physical content of your storage is simply overwritten and 
> there is no way to recover it's content by just fixing lvm2 metadata.
> 
> lvm2 provides command:� 'vgcfgrestore' - which can restore your older 
> metadata content (description which devices are used and where the 
> individual LVs use their extents - basically mapping of blocks) - 
> typically in your /etc/lvm/archive directory - and in the worst case - 
> you can obtain older metadata by scanning 1st. MiB of your physical 
> drive - data are there in ascii format in ring buffer so for your small 
> set of LVs you likely should have there full history.
> 
> When you put back your original 'drive set' - and you restore your lvm2 
> metadata to the point before you started to play with bad drive - then 
> your only hope is properly working 'fsck' - but there is nothing how 
> lvm2 can help with this.
> 
> Regards
> 
> Zdenek
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

      parent reply	other threads:[~2019-05-15 16:55 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-11 22:52 [linux-lvm] recover volume group & locical volumes from PV? "Rainer Fügenstein"
2019-05-12  0:09 ` Roger Heflin
2019-05-13  8:37 ` Zdenek Kabelac
2019-05-13 15:17   ` Rainer Fügenstein
2019-05-15 16:55   ` Rainer Fügenstein [this message]

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