Fwd: [help] how to deal with Incorrect metadata area header checksum in LVM

[max]

max wrote:
> Robin Laing wrote:
>> max wrote:
>>> Zhen Zhou wrote:
>>>> On Wed, Jun 11, 2008 at 8:45 PM, David Timms <dtimms at iinet.net.au> 
>>>> wrote:
>>>>> Zhen Zhou wrote:
>>>>>> So what is the right path to recover these lvm?
>>>>>>
>>>>>> Any tips will be welcome! Thanks in advanced,
>>>>>>
>>>>>> BTW: the attached is lvm metadata file. More detail information
>>>>>> needed, pls tell me.
>>>>> You might find experts in LVM hanging out on:
>>>>> linux-lvm at redhat.com [subscription required].
>>>>>
>>>>> Good luck.
>>>> FTA, thanks for your tips.
>>>> and I really wonder whether these errors "Incorrect metadata area
>>>> header checksum,
>>>> Volume group VolGroup00 metadata is inconsistent" is impossible to 
>>>> recover.
>>>>
>>>> Or what I need to deal, is to follow:
>>>> http://thread.gmane.org/gmane.linux.redhat.fedora.general/196481
>>>> to recover all lvm's data?
>>>>
>>>> Any tips will be welcome. TIA
>>>>
>>>> Zhou Zhen
>>>>
>>> I asked in a related thread on the developer's list and I'll ask 
>>> here. Someone please let me know if my question doesn't make any 
>>> sense. Is it harder to recover files from an LVM than with the older 
>>> partioning scheme?
>>>
>>
>> FWIW, I did recover data from an LVM that was removed (on purpose) in 
>> part of an upgrade.  I couldn't mount the drive as the LVM recovery 
>> procedures listed and I thought I was toast.  If I left the drive in 
>> the computer, the computer would try to add the drive back into the 
>> LVM no matter what I tried.
>>
>> To complicate things even further, the drive was part of a RAID 1 
>> array.  I put the drive into a carrier.  As the drive was SATA, I 
>> ended up getting a Thermaltake carrier that supports SATA and IDE (end 
>> product plug). :)
>>
>> It was many months ago but I used normal recovery tools to pull the 
>> data off of the drive.  I would have to look at my notes which are at 
>> home. If I remember I will see if I can find my notes.
>>
>> Basically, it is possible but I don't know if it is harder as this was 
>> my first time.
>>
> I suspect it is more difficult by comparison but I could easily be 
> misinterpreting what I am reading. For instance this appears on 
> wikipedia at the end of the LVM entry.
> 
>> Caveats
>>
>> The current implementation does not support write barriers. This means 
>> that any guarantee against filesystem corruption offered by journaled 
>> file systems like ext3 and XFS is negated.
> 
> It seems to imply that a lack of support for write barriers may be more 
> likely to cause/lead to/result in/not protect against corruption and 
> therefore by extension make data recovery more difficult in particular 
> cases. Though whether support for write barriers is now present I don't 
> know. I have learned a bit about file operations in searching but I am 
> still not clear on what a write barrier is, though I think I am getting 
> close, if you know of some place I can find a factual definition that 
> would be great because I have found many instances of people discussing 
> them but obviously both parties know what it is and so they never have 
> to or bother to agree on a common definition.If you can explain what a 
> write barrier is then that would be even cooler. I feel like I have most 
> of the pieces but I am missing the lynch pin that will hold it all 
> together. Though its just as likely that the answer will cause me more 
> confusion but I won't know until I find it.
> 
> Here is the url to the entry:(its not very long)
>> http://en.wikipedia.org/wiki/Logical_Volume_Manager_(Linux)
> 
> 
> 
Funny but I think I have found my answer, right under my nose as usual : )
Thanks for responding though because I probably wouldn't have seen it 
otherwise.

-- 
Fortune favors the BOLD