Re: [PATCH 0/4] nfs41: allow layoutget at pnfs_do_multiple_writes

[Trond Myklebust <Trond.Myklebust@netapp.com>]

On Tue, 2011-11-29 at 15:49 -0800, Marc Eshel wrote: 
> The only 1 cent that I can add to this argument is that I was led to 
> believe by you and others that Linux kernel don't add functionality on the 
> client side that is not supported on the server side. Last time I made 
> this point I was told that it is ok if they are of by a version or two. 
> You made it clear that this is no longer true and that the Linux client 
> and server are now independent of each other. I spent time working on the 
> server side believing that the client and server will progress more or 
> less together, disappointed to find out that it is not the case any more.
> Marc. 

I don't know how to manage layout segments in a way that meets the pNFS
goals of scalability and performance, and neither you nor the pNFS spec
have told me how to do this.

If IBM wants a client that implements layout segments, then it is _your_
responsibility to: 
     A. Convince me that it is an implementable part of the spec. 
     B. Provide me with an implementation that deals all with the
        concerns that I have.

IOW: nobody has ever promised IBM that the community would do all your
client work for you. EMC, NetApp and Panasas have implemented (most of)
the bits that they cared about; any bits that they haven't implemented
and that you care about are up to you.

-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@netapp.com
www.netapp.com