Re: [storm] iSCSI version descriptors (for SCSI SPC-4)
"David Harrington" <ietfdbh@comcast.net> Wed, 22 September 2010 04:23 UTC
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From: David Harrington <ietfdbh@comcast.net>
To: david.black@emc.com, Frederick.Knight@netapp.com, cbm@chadalapaka.com, storm@ietf.org
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Date: Wed, 22 Sep 2010 00:23:11 -0400
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Subject: Re: [storm] iSCSI version descriptors (for SCSI SPC-4)
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Hi, (as a contributor) I am not following very closely, so I have a question. > Also, this approach is potentially confusing - all 3 values > need to be in the same document, Why? Isn't it common for IANA registries to have values added from multiple documents? I presume the registry is defined in such a way that each value also includes a reference to the document that registered it. so the approach of: > > As written now, the drafts create the key in the SAM draft > (with the > > value 2), and the consolidated draft adds the value 0 and 1. would seem reasonable. Is it also not fairly likely the two documents would go through the standards process at roughly the same time? I may be missing something... dbh > -----Original Message----- > From: storm-bounces@ietf.org [mailto:storm-bounces@ietf.org] > On Behalf Of david.black@emc.com > Sent: Tuesday, September 21, 2010 11:41 AM > To: Frederick.Knight@netapp.com; cbm@chadalapaka.com; storm@ietf.org > Subject: Re: [storm] iSCSI version descriptors (for SCSI SPC-4) > > > As written now, the drafts create the key in the SAM draft > (with the > > value 2), and the consolidated draft adds the value 0 and 1. > > The current version of the consolidated draft doesn't (yet) > appear to contain the text to add the 0 and 1 values. > > Also, this approach is potentially confusing - all 3 values > need to be in the same document, which could be the SAM > draft. In addition, more IANA Considerations text is needed > to create a separate IANA registry for the values of the new > "iSCSIProtocolLevel" key and provide its initial content (all > 3 values). On the assumption that it's better to have all 3 > initial values in one place, the SAM draft would be that place. > > The consolidated draft needs to be careful about the new > "iSCSIProtocolLevel" key, as a NotUnderstood response is > acceptable for that key, in contrast to most other iSCSI > keys. If the key is defined in the SAM draft, then the > consolidated draft can say what the value 1 declares support > for and then normatively reference the SAM draft for the full > definition of the key (plus say that a NotUnderstood response > is acceptable for that new key). > > Thanks, > --David > > > > -----Original Message----- > > From: Knight, Frederick [mailto:Frederick.Knight@netapp.com] > > Sent: Tuesday, September 21, 2010 9:13 AM > > To: Black, David; cbm@chadalapaka.com; storm@ietf.org > > Subject: RE: iSCSI version descriptors (for SCSI SPC-4) > > > > Most of this is fine, but I do have 1 question. > > > > We originally debated whether to create 1 draft that included > > everything (consolidated + SAM 4/5), or to create 2 drafts (1 for > > consolidated and 1 for new SAM 4/5 features). The > consensus at the time was for 2 drafts. > > > > Put "running code" based stuff in the consolidated draft. > > > > Put all the new stuff in the SAM4/5 features draft. > > > > This suggestion (adding a new key to the consolidated > draft) sort of > > muddies the waters. I think we should be careful about > starting down > > a path where we pick and choose which new features we > decide to fold back into the consolidated draft, and which > new features we decide to exclude. > > > > As written now, the drafts create the key in the SAM draft > (with the > > value 2), and the consolidated draft adds the value 0 and 1. > > > > I'm not sure how much this matters, but we had reasons for the > > original choice we made about "running code" vs. "new" stuff, and > > while valid to revisit those reasons, I would prefer that > we do so explicitly. > > > > Fred > > > > -----Original Message----- > > From: david.black@emc.com [mailto:david.black@emc.com] > > Sent: Monday, September 20, 2010 11:46 AM > > To: cbm@chadalapaka.com; Knight, Frederick; storm@ietf.org > > Cc: david.black@emc.com > > Subject: iSCSI version descriptors (for SCSI SPC-4) > > > > It's time to come back to this topic. > > > > I believe that what should happen is to have SPC-4 point to an IANA > > registry for all iSCSI version descriptors other than the existing > > "(no version claimed)" descriptor (might be SPC-5 by the > time we get > > all the pieces in place). The reason for doing this is to > put IETF in > > a position to create new version descriptors for iSCSI > without having to ask T10 to do so (although, it makes sense > to ask T10 to reflect the currently-valid version descriptors > for iSCSI in each version of SPC). > > > > Getting this to happen requires some work. For starters, note that > > the existing 0x960 iSCSI version descriptor can be used by > any version > > of iSCSI - "no version claimed" means that no assumptions > can be made > > about presence or absence of functionality. For that reason, my > > personal (not as WG chair) preference is that we create a version > > descriptor for RFC 3720 + RFC 5048 as reflected in the new combined > > iSCSI draft, in order to provide a means for an implementation to > > promise support for the corrections and clarifications in > RFC 5048 - > > that descriptor should also promise support for NAA iSCSI > names (RFC > > 3980) and the Node Architecture key (RFC 4850). Not using > any iSCSI version descriptor, or using the existing 0x960 > version descriptor, doesn't declare absence of support - the > only valid inference that an application client (initiator) > can make is "don't know". We do need to get to a conclusion > on whether to define this version descriptor. > > > > The actual mechanics for coordinating this across IETF and > T10 involve several steps: > > (1) The "iSCSIProtocolLevel" key should be defined in the > consolidated > > iSCSI draft, including creation of an IANA registry for its > values (range: 0 - 31) and defining the first two values: > > 0 - unknown (equivalent to a NotUnderstood response to the key) > > 1 - 3720 + 5048, etc., as reflected in the consolidated > iSCSI draft. > > I included 0 for completeness - it's not strictly necessary. This > > moves creation of that key from the SAM 4/5 features update > draft to > > the main consolidated draft > > (2) The new SAM-4/5 features draft then defines the value 2 > and adds it to that IANA registry. > > (3) As an interim measure, after WG last call is completed, > we (that > > probably means Fred and I) write a T10 proposal to create > the version > > descriptors 0x961 and 0x962 (corresponding to the values > > 1 and 2 for the "iSCSIProtocolLevel" key). That makes both version > > descriptors usable, and provides an opportunity for the > (inevitable) T10 input on exactly how the values of the > "iSCSIProtocolLevel" > > key are specified. > > (4) After the RFCs are published for both drafts (yes, I'm an > > optimist), another T10 proposal then updates SPC-4 to > cross-reference the IANA registry. > > > > Combining steps (3) and (4) at T10 would require both early > creation > > of the IANA registry and early assignment of the RFC numbers. It's > > not immediately clear to me that this should be done - we > can figure out whether/how to do this at the time when the > first T10 proposal needs to be written. > > > > Comments? > > > > Thanks, > > --David > > > > > > > -----Original Message----- > > > From: Mallikarjun Chadalapaka [mailto:cbm@chadalapaka.com] > > > Sent: Monday, March 08, 2010 2:06 AM > > > To: 'Knight, Frederick'; Black, David; storm@ietf.org > > > Subject: RE: [storm] SCSI Version Descriptors - iSCSI and SAM-5 > > > > > > Agreed on the SAM-5 version descriptor. I assume the new > draft will > > > in addition reference SAM-4. > > > > > > On the iSCSI version descriptions, I actually think creating a > > > 3720+5048 version descriptor is a good start. As Fred says, > > > existing implementations will be initially not reporting > this so the > > > initiator is left to other means to figure out the > compliance level > > > (and iSCSI provides the hooks to discern that). However, > I believe > > > this new version descriptor will help provide clarity > down the road > > > as existing implementations catch up to the standard - as > opposed to > > > leaving it open-ended until all implementations catch up > to the SAM-5 draft (which takes even longer to get to). > > > > > > So I guess my preference is to create a 3720+5048 version > > > descriptor, assuming it's OK to approach T10 any time in > future with > > > a request to add additional milestones based on > implementation feedback from the WG. > > > > > > Thanks. > > > > > > Mallikarjun > > > > > > > > > > > > > -----Original Message----- > > > > From: storm-bounces@ietf.org [mailto:storm-bounces@ietf.org] On > > > > Behalf Of Knight, Frederick > > > > Sent: Tuesday, March 02, 2010 10:20 AM > > > > To: Black_David@emc.com; storm@ietf.org > > > > Subject: Re: [storm] SCSI Version Descriptors - iSCSI and SAM-5 > > > > > > > > I agree, we need to request a frozen SAM-5 version > descriptor, and > > > > see what they say. > > > > > > > > I'm reluctant to create a new descriptor to indicate compliance > > > > with something old (3720+5048). > > > > > > > > All those existing implementations that support > 3720+5048 will NOT > > > > have that descriptor. What is an initiator to think? How will > > > > the initiator tell an old compliant device that > supports 3720+5048 > > > > with no descriptor from the new compliant device that supports > > > > 3720+5048 but has the descriptor? My fear is a host > that assumes > > > > that if the 3720+5048 descriptor you propose is NOT > present, then the device must NOT be 3720+5048 compliant. > > > > > > > > I'm reluctant to punish existing compliant devices by > creating a > > > > descriptor that they will not report. The horse is > already out of > > > > the barn, what good will it do to post a "please close > the door" sign? > > > > > > > > We should however, request that T10 create a descriptor that > > > > indicates compliance with the new SAM features draft (which > > > > therefore means > > > > 3720+5048+xxx; where xxx=the new SAM features RFC). If > the device > > > > 3720+5048+doesn't > > > > report this new descriptor, then you must use iSCSI > mechanisms to > > > > determine if the device is 3720 only, or 3720+5048. > > > > > > > > Fred Knight > > > > > > > > -----Original Message----- > > > > From: Black_David@emc.com [mailto:Black_David@emc.com] > > > > Sent: Monday, March 01, 2010 5:53 PM > > > > To: storm@ietf.org > > > > Subject: [storm] SCSI Version Descriptors - iSCSI and SAM-5 > > > > > > > > <WG Chair Hat On> > > > > > > > > We have some interesting technical decisions to make > around asking > > > > for some SCSI version descriptor values. For those not > familiar > > > > with them, a SCSI device can return up to 8 2-byte version > > > > descriptors in bytes 58-73 of standard INQUIRY data > (see section > > > > 6.4.2 in SPC-3 or the latest draft of SPC- 4). A > version descriptor value specifies both a standard and a revision. > > > > Version descriptor values are defined by explicit > action at T10; > > > > this serves as an indirect control over which versions of > > > > standards to which a device can claim to comply, and > discourages > > > > compliance with revisions that are unstable or otherwise > > > > unsuitable. T10 only assigns version descriptors to > drafts of standards that T10 believes to be stable (e.g., > suitable to implement from). > > > > > > > > The straightforward decision is that the iSCSI features update > > > > draft (draft- > > > > ietf-storm-iscsi-sam) will need to reference a stable > version of > > > > the SAM-5 standard (under development) prior to the > completion of SAM-5 work at T10. > > > I > > > > suggest that Fred Knight (editor of the draft) and I > discuss this > > > > at next week's meeting of T10 (specifically, the CAP WG > in T10) in > > > > a couple of weeks and bring the resulting recommendation to the > > > > storm WG list and the Anaheim meeting. Based on what's in the > > > > current draft of SAM-5, T10 may assign a version descriptor, or > > > > recommend that we wait for some more things that are > known to be inbound. > > > > > > > > The more interesting decision is version descriptors for iSCSI. > > > > Currently, there's only a generic version descriptor value , > > > > 0x960h "iSCSI (no version claimed)". There are an > additional 31 > > > > descriptor values available to iSCSI, and so the > question to the storm WG is - what would we like to see defined? > > > > > > > > I have two initial suggestions: > > > > 1) I suggest asking that a version descriptor be > defined for the combination > > > > of RFC 3720 (iSCSI) and RFC 5048 (iSCSI > corrections and clarifications) > > > > to enable a device to claim that it has > implemented RFC 5048. We could > > > > add additional RFCs to this set, e.g., RFC 3980 > for NAA names, although > > > > I'm not sure that's useful to know post-login.' > > > > 2) I strongly suggest *not* asking that a version > descriptor be defined > > > > for RFC 3720 by itself, as I'm concerned that > such a descriptor would > > > > serve as a (small) disincentive to implement RFC 5048. > > > > Please comment on these. > > > > > > > > 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 > > > > ---------------------------------------------------- > > > > > > > > _______________________________________________ > > > > storm mailing list > > > > storm@ietf.org > > > > https://www.ietf.org/mailman/listinfo/storm > > > > _______________________________________________ > > > > storm mailing list > > > > storm@ietf.org > > > > https://www.ietf.org/mailman/listinfo/storm > > > > > > > _______________________________________________ > storm mailing list > storm@ietf.org > https://www.ietf.org/mailman/listinfo/storm >
- [storm] SCSI Version Descriptors - iSCSI and SAM-5 Black_David
- Re: [storm] SCSI Version Descriptors - iSCSI and … Knight, Frederick
- Re: [storm] SCSI Version Descriptors - iSCSI and … Mallikarjun Chadalapaka
- [storm] iSCSI version descriptors (for SCSI SPC-4) david.black
- Re: [storm] iSCSI version descriptors (for SCSI S… Ralph Weber
- Re: [storm] iSCSI version descriptors (for SCSI S… david.black
- Re: [storm] iSCSI version descriptors (for SCSI S… Knight, Frederick
- Re: [storm] iSCSI version descriptors (for SCSI S… david.black
- Re: [storm] iSCSI version descriptors (for SCSI S… David Harrington
- Re: [storm] iSCSI version descriptors (for SCSI S… david.black
- Re: [storm] iSCSI version descriptors (for SCSI S… Mallikarjun Chadalapaka
- Re: [storm] iSCSI version descriptors (for SCSI S… david.black
- Re: [storm] iSCSI version descriptors (for SCSI S… Mallikarjun Chadalapaka