Re: [Qemu-devel] Re: KVM call minutes for June 8

[Kevin Wolf]

Am 10.06.2010 14:53, schrieb Anthony Liguori:
> On 06/10/2010 04:43 AM, Kevin Wolf wrote:
>>
>> Huh, why this? Seems I still haven't understood all of qcow2 then... I
>> always thought that there's just a specific offset where VM state
>> starts, but no explicit end.
>>    
> 
> A live snapshot can last for a very long time.  What happens if you need 
> to allocate a new block for disk I/O while saving a snapshot?

You allocate it, I guess?

Note that VM state must be virtually contiguous, but not necessarily
physically (virtually = on the virtual hard disk as seen by the guest;
physically = in the image file). It's just not seen by the guest because
it's saved at a high offset that is after the end of the real disk
content, but otherwise it should behave the same as guest data.

Kevin