Re: [Qemu-block] [Qemu-devel] qemu 2.9.0 qcow2 file failed to open after hard server reset

[John Snow]

On 12/27/2017 04:47 PM, Vasiliy Tolstov wrote:
> 2017-12-22 1:58 GMT+03:00 John Snow <address@hidden>:
>>
>>
>> On 12/21/2017 05:13 PM, Vasiliy Tolstov wrote:
>>> Hi! Today my server have forced reboot and one of my vm can't start
>>> with message:
>>> qcow2: Marking image as corrupt: L2 table offset 0x3f786d6c207600
>>> unaligned (L1 index: 0); further corruption events will be suppressed
>>>
>>> i'm use debian jessie with hand builded qemu 2.9.0, i'm try to
>>> qemu-img check but it not helps. How can i recover data inside qcow2
>>> file? (i'm not use compression or encryption inside it).
>>>
>>
>> Not looking good if you're missing the very first L2 table in its entirety.
>>
>> You might be able to go through this thing by hand and learn for
>> yourself where the L2 table is (it will be a 64KiB region, aligned to a
>> 64KiB boundary, that all contain 64bit, 64KiB aligned pointers that will
>> be less than the size of the file. the offset of this missing region is
>> not likely to be referenced elsewhere in your file.)
>>
>> and then, once you've found it, you can update the pointer that's wrong.
>> However, where there's smoke there's often fire, so...
>>
>> best of luck.
>>
>> --js
> 
> If i use raw image as i understand this corruption can't happening in raw?
> 

Not this exact type of corruption, anyway. Backups are important for a
reason!

--js