Re: [Xen-devel] [RFC V9 3/4] domain snapshot design: xl

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2014-12-22 at 01:52 -0700, Chun Yan Liu wrote:
> 
> >>> On 12/19/2014 at 06:27 PM, in message 
> >>> <1418984856.20028.17.camel@xxxxxxxxxx>,
> Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote: 
> > On Fri, 2014-12-19 at 00:03 -0700, Chun Yan Liu wrote: 
> >  
> > > '--name' meant to give a meaningful name (like: newinstall. Used as the 
> > > memory snapshot name and disk snapshot name). 
> >  
> > Where is this name stored and when and where would it be presented to 
> > the user?
> e.g. For qcow2 internal disk snapshot, this name is stored within the disk.
> When user wants to delete internal disk snapshot, it will be:
> #qemu-img snapshot -d name disk

Makes sense, thanks. Can you clarify in the doc with something like
"name is used as an identifier in the underlying storage backend".

Does it have to be unique? Sounds like it does.

> > > That's good. Then we need to add some description to tell users about 
> > > the auto-generated domain snapshot name, disk snapshot name, 
> > > memory state file and external disk snapshot files, etc. 
> >  
> > We will need user docs and manpage updates, yes. 
> >  
> > > > > #e.g. to specify exernal disk snapshot, like this:  
> > > > > #disks=['/tmp/hda_snapshot.qcow2,qcow2,hda',  
> > > > >         '/tmp/hdb_snapshot.qcow2,qcow2,hdb',]  
> > > > >   
> > > > > #e.g. to specify internal disk snapshot, like this:  
> > > > > disks=[',,hda',',,hdb',]  
> > > >   
> > > > Ideally one or the other of these behaviours would be possible without  
> > > > needing to be quite so explicit. 
> > >  
> > > OK, I'll delete one. 
> >  
> > I don't object to having this more capable syntax as an option, so the 
> > user can override things if they wish, all I was suggesting is that the 
> > default ought to be something useful so the user doesn't need to say 
> > anything if they just want the toolstack to "do something sensible". 
> 
> I see. By default user doesn't need to specify 'disks' at all, then xl
> will do internal disk snapshot to each domain disk.

Right, or it could do an external snapshot to the directory it has been
told the snapshot should live in.

Ian.


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