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

[MORITA Kazutaka]

At Fri, 24 Aug 2012 01:37:11 +0800,
Yunkai Zhang wrote:
> 
> If correct one have been removed, how can fsck fix that? (I'm not
> familiar with this command, I just have some doubts.)

In my opinion, either of replicas is correct one.  As long as sheepdog
provides block device semantics, the guest os filesystem should handle
any kind of I/O errors with a journaling or fsck command.

> 
> >
> > I don't fully understand yet what situation you want to avoid.  What
> > kinds of problem happens to you if you fix consistency with wrong
> > objects?
> 
> If fsck can help me to fix, I have no question, and this patch isn't
> very important for me.

I really need a concrete example.

 - What is the scenario where the consistency problem you are trying
   to solve happen?

 - In the scenario, how do you decide which object is correct?  IMO,
   either is correct in any cases.

 - What kind of problems are you expecting when VM reads the wrong
   object?

Thanks,

Kazutaka

> 
> I just want to try our best to protect sheepdog's data integrity, I
> haven't encountered any situation in real work, I didn't even
> encountered VM's unexpected termination.
> 
> If fix consistency with wrong objects is really not harm, I do not
> mind to drop this patch.
> 
> 
> >
> > Thanks,
> >
> > Kazutaka
> 
> 
> 
> -- 
> Yunkai Zhang
> Work at Taobao
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