Re: [Qemu-devel] [PATCH] mirror: prevent 'top' mode mirroring when no backing file specified on the destination

[sochin.jiang]

 Well, that makes sense, I lose my consideration, thanks.




Sochin Jiang

On 2016/12/19 23:31, Eric Blake wrote:
> On 12/19/2016 04:38 PM, sochin jiang wrote:
>>  Mirroring using 'top' mode without backing file specified on the target can 
>> be success,
>>  but end with a disaster.
>>
>>  For example:
>>    Migration can be success in this situation while the virtual machine on 
>> the destination
>>  is no longer usable because of backing lost.
>>
> 
> I think this is a premature policy decision.  Even though the user can
> abuse it to lose data, I think there is still enough technical reason
> for why a user might have a valid use case for doing this (perhaps for
> creating incremental backups, where the user plans on re-chaining data
> back together using 'qemu-img rebase -u'), so I don't think we should
> forbid it at the qemu level.
>