Re: [storm] iSER - one last issue
"Hemal Shah" <hemal@broadcom.com> Wed, 18 January 2012 23:58 UTC
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From: Hemal Shah <hemal@broadcom.com>
To: "david.black@emc.com" <david.black@emc.com>, "Michael@huaweisymantec.com" <Michael@huaweisymantec.com>, "storm@ietf.org" <storm@ietf.org>
Thread-Topic: iSER - one last issue
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Date: Wed, 18 Jan 2012 23:55:30 +0000
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Subject: Re: [storm] iSER - one last issue
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David and Mike, I believe that the requirements should not be weakened and we should stick to the requirement in RFC5046. RFC5046 required the use of specific Send Message Type for valid reasons. In the case of requiring SendSE message use, the intent was to give a hint to the remote side to generate an event upon processing of SendSE message. For example, the SendSE is specifically carrying SCSI information that needs attention on the remote side e.g. SCSI command, Logout... In the case of requiring SendInvSE Message, the intent was to invalidate the STag used in the data transfer as well as inform the remote side to generate an event. For example, mandating the use of SendInvSE for the SCSI response PDU for a SCSI Read limits the exposure of STag used in SCSI Read data transfer and avoids the explicit invalidation of the STag at the initiator. Plus, it allows the target to generate an event on the initiator upon the completion of SCSI Read command. By relaxing RFC5046 requirements in the latest iSER draft, we will not only impact all iWARP based iSER implementations that rely on the use of specific Send Message Type for SCSI data transfers but also change the intended behavior of initiators and targets. For iWARP, I strongly suggest that the iSER draft does not relax the requirements specified in RFC5046. I hope that helps. Hemal From: storm-bounces@ietf.org [mailto:storm-bounces@ietf.org] On Behalf Of david.black@emc.com Sent: Wednesday, January 18, 2012 3:10 PM To: Michael@huaweisymantec.com; storm@ietf.org Subject: Re: [storm] iSER - one last issue Mike, Thank you for the explanation, but I don't believe you've correctly stated the intent of RFC 5046. Here are some examples from RFC 5046's text: 1.5. SCSI Read Overview The iSER Message is transferred to the target using a SendSE Message. The iSER layer at the target uses a SendInvSE Message to transfer the SCSI Response PDU back to the iSER layer at the initiator. Similar language occurs in 1.6 SCSI Write Overview. 5.2.1. Normal Connection Termination at the Initiator The iSER layer at the initiator MUST use a SendSE Message to send the Logout Request PDU to the target. Similar language occurs in 5.2.2 for target side normal connection termination, and more importantly in 7.3.1 SCSI Command: The iSER layer at the initiator MUST send the SCSI command in a SendSE Message to the target. None of the quoted text permits use of Send instead of SendSE or SendInv instead of SendInvSE. What you propose to do effectively changes "MUST" to "should" (lower case, weaker than "SHOULD"), and that sure looks like a change to RFC 5046. Are there good implementation-based reasons to weaken these requirements now? Does anyone else have a viewpoint on this topic? Thanks, --David From: Michael Ko [mailto:Michael@huaweisymantec.com] Sent: Wednesday, January 18, 2012 2:22 PM To: Black, David; storm@ietf.org Subject: Re: iSER - one last issue David, Here is my rationale for using the lower case "should". The intent of RFC5046 is that the Send Message type must be used instead of RDMA Reads or Writes. The Solicited Event feature of the Send Message is provided as a convenience. The receiver must still do the right thing in handling the Send Message regardless of whether the SE feature is used. In other words, the sender is responsible for using the right format for the message (Send vs RDMA) but the receiver must not rely on the sender to determine how to handle the received message. The same rationale goes for the Invalidate feature. Mike ----- Original Message ----- From: david.black@emc.com<mailto:david.black@emc.com> To: Michael@huaweisymantec.com<mailto:Michael@huaweisymantec.com> ; storm@ietf.org<mailto:storm@ietf.org> Sent: Monday, January 16, 2012 2:06 PM Subject: iSER - one last issue Mike, Thanks for getting the -08 version of the iSER draft posted. I think that draft addresses all of the open issues, but I have a question for the WG about how to express the SendSE and SendInvSE requirements from RFC 5046. The -08 version of the iSER draft expresses requirements for the SendSE and SendInvSE messages (this is primarily for iSER over RDDP/iWARP) as: The SendSE Message should be used if supported by the RCaP layer (e.g., iWARP). My reading of RFC 5046 is that its requirements are tighter - to accurately reflect RFC 5046, I would replace "should" with "MUST" in the above text, at least for iWARP. In the alternative, if the "should"s remain, an explanatory item needs to be added to the Appendix A list of changes from RFC 5046. What do others think the right course of action is here, use "MUST" or explain weakening of requirement to "should" ? Thanks, --David From: storm-bounces@ietf.org [mailto:storm-bounces@ietf.org] On Behalf Of Michael Ko Sent: Sunday, January 15, 2012 8:43 AM To: storm@ietf.org Subject: Re: [storm] I-D Action: draft-ietf-storm-iser-08.txt This version contains all the updates as discussed in the latest exchanges with Hemal Shah and David Black. Mike ----- Original Message ----- From: internet-drafts@ietf.org<mailto:internet-drafts@ietf.org> To: i-d-announce@ietf.org<mailto:i-d-announce@ietf.org> Cc: storm@ietf.org<mailto:storm@ietf.org> Sent: Sunday, January 15, 2012 5:40 AM Subject: [storm] I-D Action: draft-ietf-storm-iser-08.txt A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the STORage Maintenance Working Group of the IETF. Title : iSCSI Extensions for RDMA Specification Author(s) : Michael Ko Alexander Nezhinsky Filename : draft-ietf-storm-iser-08.txt Pages : 95 Date : 2012-01-15 iSCSI Extensions for RDMA provides the RDMA data transfer capability to iSCSI by layering iSCSI on top of an RDMA-Capable Protocol. An RDMA-Capable Protocol provides RDMA Read and Write services, which enable data to be transferred directly into SCSI I/O Buffers without intermediate data copies. This document describes the extensions to the iSCSI protocol to support RDMA services as provided by an RDMA- Capable Protocol. This document obsoletes RFC 5046. A URL for this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-ietf-storm-iser-08.txt Internet-Drafts are also available by anonymous FTP at: ftp://ftp.ietf.org/internet-drafts/ This Internet-Draft can be retrieved at: ftp://ftp.ietf.org/internet-drafts/draft-ietf-storm-iser-08.txt _______________________________________________ storm mailing list storm@ietf.org<mailto:storm@ietf.org> https://www.ietf.org/mailman/listinfo/storm
- [storm] I-D Action: draft-ietf-storm-iser-08.txt internet-drafts
- Re: [storm] I-D Action: draft-ietf-storm-iser-08.… Michael Ko
- [storm] iSER - one last issue david.black
- Re: [storm] iSER - one last issue Michael Ko
- Re: [storm] iSER - one last issue david.black
- Re: [storm] iSER - one last issue Hemal Shah
- Re: [storm] iSER - one last issue Tom Talpey
- Re: [storm] iSER - one last issue Hemal Shah
- Re: [storm] iSER - one last issue Tom Talpey
- Re: [storm] iSER - one last issue Hemal Shah
- Re: [storm] iSER - one last issue Michael Ko