Subject: RE: [nfsv4] Global namespace for v4.1?

From: "Noveck, Dave" <[email-masked]>
Date: Mon, 22 Dec 2003 07:07:34 -0800

> It is not the granularity that I am after. I could live with directories
> or even subtrees.

OK, glad to hear it.

I was going by your statements:

> IMHO a good global namespace should be imposed without artificially restricting 
> the way components are placed. 

> It should also not have (or not have it standardized) a mapping to local namespaces. 
> I.E., in theory a file in the global namespace may be located anywhere.
 
> Probably you may want to restrict this to directories but you should not go 
> beyond this. 

>From which I concluded that the current v4 model, which made fs's (significant
trees) the unit of migration and referral, was not acceptable to you.

> The thing that I am concerned about is that building a global map based on an 
> "arbitrary" composition of local maps will not get you the transparency that 
> every enterprise is looking for - location transparency, migration transparency, 
> replication transparency. Transparency is what will keep applications and 
> administration separate. 

Maybe I'm not understanding the problem you are worried about.  As far as what
I have proposed, each fs can be at an arbitrary position within the namespace,
and that typically will not depend on the server or servers on which the fs is 
currently hosted.  Does that address your concern?

> As for teleport - I never though about AFS in those terms (should I have?).

I don't know AFS well enough to understand how it deals with the granularity
issue.  I know there is a global namespace but is it the case that directories
within it can be arbitrarily located and still manipulated as if they were
within a single fs?  If so, then it does seem to me kind of science-fictional 
and something that is rather distant, in the context of a protocol like NFS 
where multiple separately-derived implementations need to interoperate.

The v4 approach relies, for its simplicity, on the fact that the separately
located subtrees are separate fs's and thus you cannot link files between them,
move directories between them, etc.  That's why I characterized that as "walking",
i.e. something we know how to do, can be done within the bounds of RFC3530,
albeit with a number of rough edges, and only requires that we travel the
road laid out for us, putting one foot in front of the other.

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From: Julian Satran <[email-masked]>
Date: Mon, 22 Dec 2003 18:56:34 +0200

> currently hosted.  Does that address your concern?
Arbitrary in reference to what? If it is in a fixed position in the global 
namespace that addresses my concern.
> where multiple separately-derived implementations need to interoperate.
Not necessarily - in AFS the "local names" in the local filespace have no 
relevance to the global names
However the same effect could be achieved with "bigger granules". 
Interoperability - I am not aware of any interopearbility issues that 
become simpler by that or another choice of building the global tree.
If you limit yourself to referrals servers or the referal-servers will 
have to guarantee the "unique" structure of the global name-space.

> road laid out for us, putting one foot in front of the other.
I am not sure that I would characterize moving directories as a bad thing