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

"Felix Marti" <felix@chelsio.com> Mon, 23 March 2009 16:37 UTC

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Date: Mon, 23 Mar 2009 09:36:44 -0700
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Thread-Topic: [Junk released by Allow List] Re: [rddp] [Ips] Storage Maintenance (storm) BOF reminder & requests
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From: "Felix Marti" <felix@chelsio.com>
To: "Robert D. Russell" <rdr@iol.unh.edu>, <Black_David@emc.com>
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Cc: imss@ietf.org, ips@ietf.org, rddp@ietf.org
Subject: Re: [imss] [Junk released by Allow List] Re: [rddp] [Ips] Storage Maintenance (storm) BOF reminder & requests
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> -----Original Message-----
> From: rddp-bounces@ietf.org [mailto:rddp-bounces@ietf.org] On Behalf
Of
> Robert D. Russell
> Sent: Sunday, March 22, 2009 8:42 AM
> To: Black_David@emc.com
> Cc: imss@ietf.org; ips@ietf.org; rddp@ietf.org
> 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, Black_David@emc.com 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
> >
> > The initial agenda is here:
> > 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
> > +1 (508) 293-7953             FAX: +1 (508) 293-7786
> > black_david@emc.com        Mobile: +1 (978) 394-7754
> > ----------------------------------------------------
> > _______________________________________________
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> > Ips@ietf.org
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> >
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