Hello Juergen

to your question: 
"> So why do we need 'local data mount' (aka 'alias mount')? Which 
> problem does it solve that 'peer mounting' localhost does not solve?"

Yes, you could apply peer mounting to a local host as a special case.  
Certainly there is nothing that should prevent that.  However, the distinction 
is still relevant.  For one, in the peer mounting case, the remote host is 
considered the authoritative owner, the mounting host is _not_ the 
authoritative owner.  In alias mount, since it is the same owner, it has 
authority.  

The fact that in peer mount the local host has no authority means that the use 
cases primarily targeted involve cases that require visibility of data and 
support for a data retrieval, read-only view.  One of the concerns that had 
been raised earlier were the ramifications that transactional behavior and 
locking etc would have in a distributed scenario.  Given that alias-mount is 
local, things are simplified and use cases that go beyond pure providing 
visibility easier to support.  So, alias mounting may be an important special 
case of peer mounting, but also a simple case.  This is a fact that we would 
like to leverage.  

In practical terms, alias mount and peer mount can look very similar.  Peer 
mount involves an additional parameter (to identify the target system), with 
corresponding additional mountpoint management ramifications.  So, peer mount 
can in that sense build on top of, or extend, alias mount.  

--- Alex

-----Original Message-----
From: Eric Voit (evoit) 
Sent: Friday, April 08, 2016 6:33 AM
To: Juergen Schoenwaelder <j.schoenwael...@jacobs-university.de>
Cc: Martin Bjorklund <m...@tail-f.com>; kwat...@juniper.net; Alexander Clemm 
(alex) <a...@cisco.com>; netmod@ietf.org
Subject: RE: [netmod] kw comments on draft-voit-netmod-yang-mount-requirements

> From: Juergen Schoenwaelder, April 08, 2016 2:58 AM
> 
> On Fri, Apr 08, 2016 at 02:20:19AM +0000, Eric Voit (evoit) wrote:
> > My thinking matches more closely to what Kent lays out above:
> >
> > schema-mount
> > data-mount
> > remote data mount   (a.k.a. peer mount)
> > local data mount        (a.k.a. alias mount)
> >
> > The value in the term "yang mount" is that it provides a conceptual 
> > umbrella to
> ensure a cohesive syntax across the four valid permutations of the 
> above.  The term itself was never intended to be implementable.
> >
> 
> So why do we need 'local data mount' (aka 'alias mount')? Which 
> problem does it solve that 'peer mounting' localhost does not solve?

To me it comes down to ease of use for the developer. If the system only allows 
mounting localhost, why require that parameter in the syntax?   That parameter 
shouldn't even be available/visible for entry. 

Eric

> /js
> 
> --
> Juergen Schoenwaelder           Jacobs University Bremen gGmbH
> Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
> Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>

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