[sheepdog] [PATCH V2 4/4] collie: introduce '-o, --oid' option to 'collie vdi read' command

[Yunkai Zhang]

On Thu, Aug 23, 2012 at 10:20 PM, MORITA Kazutaka
<morita.kazutaka at lab.ntt.co.jp> wrote:
> At Thu, 23 Aug 2012 21:46:55 +0800,
> Yunkai Zhang wrote:
>>
>> When inconsistency happens, in the worst case, we just need to make
>> replicas with the same value but needn't to care about which replica
>> is correct.
>>
>> But in the best case, only several objects were polluted, then this
>> patch can give us a chance to verify them, This patch is used to work
>> with 'collie vdi check' command, that is my original intention when
>> developed it.
>
> Well, replica inconsistency happens only when the VM terminates
> unexpectedly.  If the vm image needs a fix, the guest os filesystem
> should fix it.  What sheepdog should do is only keeping consistency so

Can you explain how the guest os files system fix it?

I had discussed with Yuan, he told me that these inconsistent replicas
is useless for VM. If so, I will have another question: why not delete
it directly? Or if these replicas are useful data, How can we randomly
select a replica?

> that the VMs doesn't read the wrong data as a block storage, isn't it?
> Have you ever encountered a situation where you need to specify a
> replica to be recovered?
>
> Thanks,
>
> Kazutaka



-- 
Yunkai Zhang
Work at Taobao