[linux-lvm] rescue data after hd crash

chris cspot at gmx.at
Wed May 31 22:39:39 UTC 2006

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-mapper ioctl cmd 9 failed: Das Argument ist ungültig"
  (i hate german error messages, who invented this? it says "illegal  

but also "1 logic voliume(s) .. now active".

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 at 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
>> _______________________________________________
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>> linux-lvm at redhat.com
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>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

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