Re: [Qemu-devel] [PATCH V4 4/4] Change default to qcow2 for sync mode none.

[Eric Blake]

On 07/18/2013 12:03 PM, Ian Main wrote:
>>
>> Or we could simplify life by making 'format' mandatory for drive-backup;
>> it was optional for 'drive-mirror' due to incremental implementation,
>> but for 'drive-backup', we still have the opportunity to do things right
>> from the first release.
> 
> Ah, I did make a doc change, I must have forgotten to add it.
> 
> I'm all for making format mandatory if that is ok with everyone.  Maybe
> that is the best solution.

We can always change our mind in 1.7 to make it optional if we change
our minds, but I'd definitely like to see patches that make 'format'
mandatory for DriveBackup for 1.6 - simpler all around.  Converting
mandatory to optional is discoverable via introspection; while
converting optional to mandatory is an API break.  And since we can
argue that optional formats is relatively risky, it's better to have our
initial release be conservative by requiring the field until (and
unless) someone comes up with a use case why leaving it unspecified
makes a difference.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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