Re: [Qemu-devel] [PATCH] Revert block-qcow2.c to kvm-72 version due to corruption reports

[Anthony Liguori <anthony@codemonkey.ws>]

Jamie Lokier wrote:
> Anthony Liguori wrote:
>   
>>>> And let's be clear, your data is *not* safe with qcow2.  So I don't 
>>>> consider this to be a show stopping issue.
>>>>         
>>> I beg your pardon?  The one format that was recommended for quite a long 
>>> time now is considered unsafe?
>>>       
>> It's always been that way.  It's unsafe for a number of reasons that 
>> have been discussed at great length.
>>     
>
> It sure isn't mentioned in the documentation.
> If it was, I would never have used it, and I imagine I'm not alone.
>
> QEMU might be an emulator project where people expect quirks, but KVM
> and Xen are professional virtualisation platforms competing with
> VMware.
>
> It is really not very professional that the documentation places "your
> data is not safe" formats on an equal footing with safe formats -
> without saying anything about it - and doesn't even recommend one or
> the other.
>   

Please submit patches.  I don't disagree with you and that is why I'm 
trying to make this clear now.

> That said, maybe Microsoft is doing the same thing - their
> documentation happily recommends their VHD format if you're not
> concerned about running out of disk space, and it's maybe VHD has
> similar corruption windows.
>   

Yeah, it's hard to make a truly reliable format that isn't raw.  It 
basically is the same problem file systems solve and requires either a 
journal or an fsck step.  I'm thinking that this is a problem for other 
software too.

Regards,

Anthony Liguori

> -- Jamie
>
>
>