Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format

[Kevin Wolf]

Am 13.09.2010 15:07, schrieb Anthony Liguori:
> On 09/13/2010 06:03 AM, Kevin Wolf wrote:
>>
>> The real reason why it's not the same story is that a qcow3 would be
>> backwards compatible. Old images would just work as qcow3 by changing
>> the version number in the header. Even if they are on a block device.
>> Even if they are encrypted. Even if they are compressed. Even if they
>> have internal snapshots.
>>    
> 
> I think that's really the point of QED.  I think the features of qcow2 
> make it prohibitively difficult to achieve correctness and good peformance.

I know and I understand that. I'm not even saying that it's necessarily
a bad thing (though I think that having to maintain one format is better
than having to maintain two formats).

But then you can't say it's the same story as qcow3.

>> We would have just one driver instead of two, and we could tell people
>> the upgrade their images and they didn't have to care about feature loss.
> 
> If the features don't work correctly, is it really feature loss?

Obviously the features work correctly enough for people to use them
without complaints (other than performance currently, of course).

Or let me rephrase that: Where are your bug reports?

Kevin