Subject: Re: [nfsv4] Individual i-d on v4.0 migration issues

From: "Myklebust, Trond" <[email-masked]>
Date: Thu, 01 Sep 2011 18:23:08 -0400

Whoops. I meant to say that "All servers that want to support migration MUST..."

It's not just restricted to multi -homed ones.

Trond Myklebust <[email-masked]> wrote:

On Thu, 2011-09-01 at 14:22 -0700, Robert Thurlow wrote: 
> Myklebust, Trond wrote:
> 
> > How about something like the following suggestion?
> > 
> > 1) Servers that support trunking SHOULD allow a client to determine all
> > ports on which the server is listening using a COMPOUND of the form
> > PUTROOTFH; GETATTR fs_locations.
> > 
> > 2) A client that want to use the "uniform model" MUST query fs_location=
> > on the server root filehandle prior to calling
> > SETCLIENTID/SETCLIENTID_CONFIRM. If the server does not support
> > fs_locations on the rootfh, then the client SHOULD use a unique long
> > form client id and MAY assume that the server does not support
> > migration(?), OR that a migration event must follow the non-uniform
> > model(?). Otherwise, the client may use RENEW requests on all the IP
> > addresses in order to discover on which ones a given lease applies.
> 
> "PUTROOTFH; GETATTR fs_locations" can't be anything magical -
> that is the proper way for a current NFSv4 client to inquire
> about alternate replicas of this filesystem, in the complete
> absence of migration.  We have implemented support for this.

That is 100% intentional. I'm just trying to formulate a way of
implementing the uniform model that can deal with multi-homed servers
(which I still see as a problem) _without_ introducing any new magic or
unexpected uses of the protocol.

The only new thing, is the implication that multi-homed servers that
want to support migration MUST do the above so that clients that want to
use the uniform model can detect when they are trunking.

Cheers
  Trond
-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
[email-masked]
www.netapp.com