Subject: [nfsv4] WG Last Call comments: NFS RDMA Drafts

From: [email-masked]
Date: Sun, 24 Sep 2006 18:46:29 -0400

--- draft-ietf-nfsv4-nfs-rdma-problem-statement-04.txt ---

I think section 6, which discusses RDMA as an enabler for improving
NFS semantics should be deleted from this draft for three reasons:
(1) This sort of semantic change is in the province of the
	NFSv4.1 draft and similar drafts.  
(2) I don't believe the argument that RDMA is a necessary prerequisite
	to these sorts of semantic changes.
(3) The performance results discussed in Section 4 suggest
	that a mix of conventional NFS ops for small operations
	with NFS/RDMA ops for large operations is attractive.
	Support of that combo probably rules out RDMA-specific
	modifications to NFS semantics.

Nits:

Section 2 - first paragraph should explicitly say that lack of
alignment of NFS file data as it is received causes a copy in
NFS implementations.

Section 2, p.5:

     RDMA implementations generally have other interesting properties,
     such as hardware assisted protocol access, and support for user
     space access to I/O.

"interesting" is a peculiar word.  I'd suggest deleting this sentence. 

--- draft-ietf-nfsv4-rpcrdma-03.txt ---

Section 5.1 has a diagram for use of RDMA for a long Reply, but not
for a long Call.  This ought to at least be noted in the text if the
additional long Call diagram is not added.  I assume the RDMA write
optimization is not available for long Calls - this should be stated. 

The IANA considerations section does not tell IANA which registry to
allocate the "netid" from or what additional information to record
about the allocated "netid".

Section 6.2 appears to require IANA to assign a program number, but
that's not noted in the IANA Considerations section.

--- draft-ietf-nfsv4-nfsdirect-03.txt ---

I was expecting RFC 2119 language (MUST/SHOULD/MAY) and didn't
see it.  For example in the first sentence of section 4:

   The server will ignore a Write list for any
   other NFS procedure, as well as any Write list entries beyond the
   first in the list.

The "will" should be a "MUST".

Also in section 4:

   (approximately 12KB/36KB would be vastly sufficient in the
   above cases), 

It's not clear what the "/" is supposed to mean.

The end of section 5 appears to imply that NFS/RDMA cannot be
configured without the NFSv4.1 addition.  Some more explanatory
text about appropriate use of RDMA with NFSv4.0 and NFSv4.1 would
be helpful here (e.g., the configuration assumptions that are to
be used with 4.0 in the absence of the configuration additions to 4.1).

The first paragraph in the IANA Considerations section is confusing
- IANA needs to be told whether or not to allocate the additional
port number, and it looks like the allocation needs to be done.

Thanks,
--David
----------------------------------------------------
David L. Black, Senior Technologist
EMC Corporation, 176 South St., Hopkinton, MA  01748
+1 (508) 293-7953             FAX: +1 (508) 293-7786
[email-masked]        Mobile: +1 (978) 394-7754
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