Re: [linux-lvm] rescue data after hd crash

From: Heinz Mauelshagen <mauelshagen@redhat.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Cc: mauelshagen@redhat.com
Subject: Re: [linux-lvm] rescue data after hd crash
Date: Thu, 1 Jun 2006 01:25:57 +0200	[thread overview]
Message-ID: <20060531232557.GP2242@redhat.com> (raw)
In-Reply-To: <optafs8dpg51dxvh@notebook_chl.intern>

On Thu, Jun 01, 2006 at 12:39:39AM +0200, chris wrote:
> Thanks Heinz,
> 
> this looks like what i was serching for. still, it didn't work out.
> 
> the first call of this command issued (apart from multiple "couln't find  
> device..")
> "device-mapper ioctl cmd 9 failed: Das Argument ist ungï¿½ltig"
>  (i hate german error messages, who invented this? it says "illegal  
> argument")
> 
> but also "1 logic voliume(s) .. now active".

Well, looks like your Logical Volume got activated.
Of course with a hole punched out (the missing drive).

Try to mount it manually.

Heinz

> 
> lvscan says "Volume group ... not found"
> mount fails.
> 
> what should i try next?
> 
> regards, Chris
> 
> PS: about the stripes, I don't think I have any.
> 
> On Wed, 31 May 2006 23:31:54 +0200, Heinz Mauelshagen  
> <mauelshagen@redhat.com> wrote:
> 
> >
> >vgchange -ay --partial
> >
> >On Wed, May 31, 2006 at 01:45:46PM +0100, Graham Wood wrote:
> >>On Wed, May 31, 2006 at 02:34:04PM +0200, chris wrote:
> >>> I have create a volume group with 4 250GByte harddisks with an ext3  
> >>file
> >>> system on the 1TB result.
> >>Stripe or concat?
> >>
> >>> now the third harddisk failed and the volume group is "dead" -  
> >>obviously.
> >>The way you created the volume had no redundancy - therefore 25% of  
> >>your data is gone, as
> >>well as the volume's "completeness".
> >>
> >>If you did a concat, then you (with playing) may be able to get some  
> >>data back from the
> >>first 500GB of the volume - but I wouldn't want to rely on anything  
> >>that came back from it.
> >>I'd suggest getting hold of 2 identical blank disks, and doing a binary  
> >>(dd) copy of disks 1
> >>and 2 to them - and then work on them.  You might be able to use  
> >>vgcfg{backup,restore} to
> >>tell the system that this volume is actually only on 2 disks....   
> >>However, anything that
> >>references data > 500GB into the volume is almost definitely lost -  
> >>because although you've
> >>got 750G-1TB, it's almost all going to be linked back into the section  
> >>that you've lost.
> >>
> >>If you did a stripe, then you can forget getting any data back off it.   
> >>You've lost every
> >>4th block of whatever size you striped on.  E.g. with a 64k stripe  
> >>size, you'll have lost
> >>from 128k-192k, 384k-448k, etc. - and there's almost definitely going  
> >>to be nothing
> >>salvagable from that.
> >>
> >>Graham
> >>
> >>_______________________________________________
> >>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/
> >
> 
> 
> _______________________________________________
> 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/

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Heinz Mauelshagen                                 Red Hat GmbH
Consulting Development Engineer                   Am Sonnenhang 11
Storage Development                               56242 Marienrachdorf
                                                  Germany
Mauelshagen@RedHat.com                            PHONE +49  171 7803392
                                                  FAX   +49 2626 924446
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