[linux-lvm] Partition table gone? Any way to restore?

[oliver]

Well that's one of the things I need to know. How do I recover the 
partition. Only the first few bytes are missing from what I can tell.

'normally' an LVM disk would say that it didn't contain a valid 
partition.  That part is missing from the disk and needs to be recoverd.

I've read that one could try pvcreate; vgcfgrestore.

I'm firstly making a backup of the disk with dd if=/dev/hde 
of=/mnt/hd/hde_raw_dump to ensure i can always 'go back' when I mess up.

gpart found my reiserfs partition (from the VG) so I suspect that all 
the data is still AOK. I'm just a little 'scared' to run pvcreate; 
vgcgrestore because when I want to 'list' my vgcgrestore I get the 
following error:

root at enterprise:/mnt/hd# vgcfgrestore -n vg00 -l
vgcfgrestore -- INFO: using backup file "/etc/lvmconf/vg00.conf"
vgcfgrestore -- ERROR: different structure size stored in 
"/etc/lvmconf/vg00.conf" than expected in file vg_cfgrestore.c [line 120]
vgcfgrestore -- ERROR "vg_cfgrestore(): read" restoring volume group "vg00"

I suppose this could be because of the missing PV and it won't work 
untill I have all three PV's up again. However 'listing' should be fine?

Jean-Luc Coulon (f5ibh) wrote:

> Le 02.03.2005 20:26:22, oliver a écrit :
>
>> Thanks! However the partition is fine and fit so I should be able to  
>> dd everything off of it.
>>
>> The output of gpart was the following:
>> root at enterprise:~# gpart -w hmlvm,1.5 /dev/hde
>>
>> Begin scan...
>> Possible partition(ReiserFS filesystem), size(50431mb), offset(14mb)
>>
>> * Warning: short read near sector(120103011), 64512 bytes instead of  
>> 66048. Skipp
>> ing...
>> End scan.
>>
>> Checking partitions...
>> Partition(Linux ext2 filesystem): primary
>> Ok.
>>
>> Guessed primary partition table:
>> Primary partition(1)
>>   type: 131(0x83)(Linux ext2 filesystem)
>>   size: 50431mb #s(103284656) s(29799-103314454)
>>   chs:  (29/9/1)-(1023/15/63)d (29/9/1)-(102494/7/62)r
>>
>> Primary partition(2)
>>   type: 000(0x00)(unused)
>>   size: 0mb #s(0) s(0-0)
>>   chs:  (0/0/0)-(0/0/0)d (0/0/0)-(0/0/0)r
>> <snip> part 3 and 4 where 'unused'.
>>
>> Now gpart found something, however not the missing LVM PV i was  
>> hoping. Or atleast, I don't think so. I will google around to see 
>> how  to make a 1 on 1 copy of this disk, and then try to write it. 
>> I'll  report back. In the mean time, keep those ideas comming : )
>>
>
> Just an idea, be careful, it is not the *truth* as I have not tested 
> it  yet.
>
> Here is what I *think* :
> The partition type is no matter for lvm.
> Recover the partition as you like then do a fdisk to change the  
> partition type to 8E ... and see (or pray)
>
> J-L
>
> ( ... ]
>
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