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

[Daniel P. Berrange]

On Thu, Dec 21, 2017 at 05:58:47PM -0500, John Snow wrote:
> 
> 
> 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.)

Fun. That rather makes you wish that every single distinct type of table
in QCow2 files had a unique UUID value stored in it, to make forensics
like this easier :-)

Regards,
Daniel
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