Re: [rddp] [Junk released by Allow List] Re: [Ips] Storage Maintenance (storm) BOF reminder & requests

[Mikkel Hagen <[e-mail]>]

My impression is that while it does technically start in streaming mode, if it receives anything other than a MPA request it will abort the connection, thus not being usable at all?

Mikkel Hagen
Research and Development
Data Center Bridging/FC/OFA/SAS/SATA/iSCSI/iWARP Consortiums
Phone:[phone]  Fax:[phone]
UNH-IOL
121 Technology Drive, Suite 2
Durham, NH 03824

Felix Marti wrote:

-----Original Message-----
From: [e-mail] [mailto:[e-mail]] On Behalf
    

Of
  

Robert D. Russell
Sent: Sunday, March 22, 2009 8:42 AM
To: [e-mail]
Cc: [e-mail]; [e-mail]; [e-mail]
Subject: [Junk released by Allow List] Re: [rddp] [Ips] Storage
Maintenance (storm) BOF reminder & requests

David:

There are 2 issues I would like to suggest for discussion at the BOF
meeting later this week.  Both have to do with the iSER spec, RFC
    

5046.
  

1. At the present time, as far as I know, no existing hardware,
    neither Infiniband nor iWARP, is capable of opening a connection
    in "normal" TCP mode and then transitioning it into zero-copy
    

mode.
  

    Unfortunately, the iSER spec requires that.
    Can't we just replace that part of the iSER spec?
    Otherwise, all hardware and all implementations are non-standard.
    

[felix] Note that iWarp does start life as a 'streaming' connection
(normal) and is then upgraded to iWarp (zero-copy). However, you might
refer to the fact that linux doesn't support this, as the linux network
stack maintainers are unwilling to properly integrate iWarp devices.
 
  

2. The OFED stack is used to access both Infiniband and iWARP
    

hardware.
  

    This software requires 2 extra 64-bit fields for addressing
    on both Infiniband and iWARP hardware, but these fields
    are not allowed for in the current iSER Header Format.
    Can't we just add those extra fields to the iSER spec?
    If someday some other implementation doesn't need those
    fields, they can be just set to 0 (which is what is implied by
    the current iSER standard anyway).  Again, by not doing this,
    all implementations are non-standard.

In other words, I'm suggesting that we consider replacing the relevant
parts of the current iSER specs with the current OFED specs on these
2 issues.

Thanks for your consideration,
Bob Russell

Note: The following (old) posting by Mike Ko states that the
extra header fields are needed only by IB, not by IETF
(i.e., iWARP), because IB uses nZBVA, whereas iWARP uses ZBVA.

But are there any IETF/iWARP implementations out there that actually
use ZBVA with iWARP RNICs?  (I don't mean software simulations of
the iWARP protocol.)  We have built an iSER implementation that
uses the OFED stack to access both IB and iWARP hardware, and for
both of them we need to use the extra iSER header fields (nZBVA).
Perhaps this is an issue with the design of the OFED stack, which
was built primarily to access IB hardware and therefore reflects
the needs of the IB hardware.  But we found that the only way to
access iWARP hardware via the OFED stack was to used the expanded
(nZBVA) iSER header (and to use a meaningful value in the extra field,
NOT to just set it to zero).

In any case, rather than have 2 different versions of the iSER header,
it would be better to have just one, regardless of the underlying
technology involved (after all, isn't that what a standard is for??).
This is especially relevant when using the OFED stack, because,
as we have demonstrated, software built on top of the OFED stack can
(AND SHOULD!) be able to run with EITHER IB or iWARP hardware,
with NO change to that software.  Having 2 different iSER headers
does NOT make that possible!


    

2008/4/15 Mike Ko <mako at almaden.ibm.com>:

VA is a concept introduced in an Infiniband annex to support iSER.
      

It
  

appears in the expanded iSER header for Infiniband use only to
      

support the
    

non-Zero Based Virtual Address (non-ZBVA) used in Infiniband vs the
      

ZBVA
    

used in IETF.
      

Mike - could you please put me in contact with someone who has
    

actually
  

implemented iSER on top of IETF/iWARP hardware NICs using ZBVA?

    

"The DataDescriptorOut describes the I/O buffer starting with the
      

immediate
    

unsolicited data (if any), followed by the non-immediate unsolicited
      

data
    

(if any) and solicited data." If non-ZBVA mode is used, then VA
      

points to
    

the beginning of this buffer. So in your example, the VA field in
      

the
  

expanded iSER header will be zero. Note that for IETF, ZBVA is
      

assumed and
    

there is no provision to specify a different VA in the iSER header.
      

Mike - I believe this VA field in the expanded iSER header is almost
NEVER zero -- it is always an actual virtual address.

    

Tagged offset (TO) refers to the offset within a tagged buffer in
      

RDMA Write
    

and RDMA Read Request Messages. When sending non-immediate
      

unsolicited
    

data, Send Message types are used and the TO field is not present.
      

Instead,
    

the buffer offset is appropriately represented by the Buffer Offset
      

field in
    

the SCSI Data-Out PDU. Note that Tagged Offset is not the same as
      

write VA
    

and it does not appear in the iSER header.

Mike
      

On Wed, 11 Mar 2009, [e-mail] wrote:

    

This is a reminder that the Storage Maintenance BOF will
be held in about 2 weeks at the IETF meetings in San Francisco.
Please plan to attend if you're interested:

THURSDAY, March 26, 2009
Continental 1&2  	TSV  	storm  	 Storage Maintenance BOF

The BOF description is at:
http://www.ietf.org/mail-archive/web/ips/current/msg02669.html" rel="nofollow">http://www.ietf.org/mail-archive/web/ips/current/msg02669.html

The initial agenda is here:
http://www.ietf.org/mail-archive/web/ips/current/msg02670.html" rel="nofollow">http://www.ietf.org/mail-archive/web/ips/current/msg02670.html

I'm going to go upload that initial agenda as the BOF agenda,
and it can be bashed at the meeting.

The primary purpose of this BOF is to answer two questions:
(1) What storage maintenance work (IP Storage, Remote Direct
	Data Placement) should be done?
(2) Should an IETF Working Group be formed to undertake that
	work?

Everyone gets to weigh in on these decisions, even those who
can't attend the BOF meeting.  Anyone who thinks that there is
work that should be done, and who cannot come to the BOF meeting
should say so on the IPS or RDDP mailing lists (and it'd be a
good idea for those who can come to do this).  As part of the
email, please indicate how you're interested in helping (author
or co-author of specific drafts, promise to review and comment
on specific drafts).

Here's a summary of the initial draft list of work items:
- iSCSI: Combine RFCs into one document, removing unused features.
- iSCSI: Interoperability report on what has been implemented and
	interoperates in support of Draft Standard status for iSCSI.
- iSCSI: Add backwards-compatible features to support SAM-4.
- iFCP: The Address Translation mode of iFCP needs to be deprecated.
- RDDP MPA: Small startup update for MPI application support.
- iSER: A few minor updates based on InfiniBand experience.

Additional work (e.g., updated/improved iSNS for iSCSI, MIB changes,
updated ipsec security profile [i.e., IKEv2-based]) is possible if
there's interest.

There are (at least) four possible outcomes:
(A) None of this work needs to be done.
(B) There are some small work items that make sense.  Individual
	drafts with a draft shepherd (i.e., David Black) will
	suffice.
(C) A working group is needed to undertake more complex work
	items and reach consensus on design issues.  The WG can
	be "virtual" and operate mostly via the mailing list
	until/unless controversial/contentious issues arise.
(D) There is a lot of complex work that is needed, and a WG
	that will plan to meet at every IETF meeting should be
	formed.

Please note that the IETF "rough consensus" process requires a
working group in practice to be effective.  This makes outcome
(C) look attractive to me, as:
- I'm coming under increasing pressure to limit travel, and
	the next two IETF meetings after San Francisco are not
	in the US.
- I'd rather have the "rough consensus" process available and
	not need it than need it and not have it available.

Setting an example for how to express interest ...

---------------
I think that the iSCSI single RFC and interoperability report are
good ideas, but I want to see a bunch of people expressing interest
in these, as significant effort is involved.  It might make sense
to do the single iSCSI RFC but put off the interoperability report
(the resulting RFC would remain at Proposed Standard rather than
going to Draft Standard), as I'm not hearing about major iSCSI
interoperability issues.

I think the latter four items (SAM-4 for iSCSI, deprecate iFCP
address translation, MPI fix to MPA and iSER fixes) should all
be done.

I plan to author the iFCP address translation deprecation draft,
and review all other drafts.

I think that a virtual WG should be formed that plans to do its
work primarily via the mailing list.  I believe the SAM-4 work
by itself is complex enough to need a working group - I would
expect design issues to turn up at least there and in determining
whether to remove certain iSCSI features, but I'm cautiously
optimistic that the mailing list is sufficient to work these
issues out (and concerned that travel restrictions are likely to
force use of the mailing list).

-----------------

Ok, who wants to go next?

Thanks,
--David
----------------------------------------------------
David L. Black, Distinguished Engineer
EMC Corporation, 176 South St., Hopkinton, MA  01748
[phone]             FAX: [phone]
[e-mail]        Mobile: [phone]
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