[sheepdog-users] Start a guest from a snapshot

MORITA Kazutaka morita.kazutaka at lab.ntt.co.jp
Fri Mar 22 07:10:18 CET 2013


At Fri, 22 Mar 2013 13:33:57 +0800,
Liu Yuan wrote:
> 
> On 03/21/2013 10:49 PM, MORITA Kazutaka wrote:
> > If we start from a snapshot, a new writable vdi will be created as its
> > child.  The previous writable vdi will be kept as a snapshot because
> > we allows only one writable vdi for each vdi name.  If you want to
> > keep two writable vdi, you have to create a different vdi name (I
> > think this restriction is same as VMware or VirtualBox).
> > 
> 
> Ah, I see. So starting a VM on a snapshot means that we actually run on
> the newly created child, which idx = 0?

Yes, exactly.

> 
> >> > better seen as a clone. Kazutaka, is this intentional? How about marking
> >> > this VDI as clone?
> > IIUC, we mark a vdi as clone only when it is cloned from the other vdi
> > name.  However, to be honest, I don't understand the intention of 'c'
> > mark in the vdi list.  It's you who merge the patch to introduce the
> > mark, so if you think we should mark the vdi as clone, I'm not against
> > it.
> 
> 'Clone' means a writable VDI which is based(sharing data) on a read-only
> snapshot. I thought starting a VM on a snapshot will create another
> writable VDI with the same name. So this is not the case, we shouldn't
> mark it as clone.

Okay.

Thanks,

Kazutaka



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