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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] questions about draft-chadalapaka-command-ordering-00.txtI thank the authors for creating a document which "... provides guidance to system designers on how true command ordering solutions can be built based on iSCSI." As a systems designer, I welcome such an effort. I find the command ordering and recovery issues to be the most confusing aspect of the iSCSI standard. I have a few questions about the draft... 1) I think that the draft currently implies the section below from iSCSI is not always a MUST. Is this the authors intent? (From draft-ietf-ips-iscsi-20.txt) 3.2.2.1 Command Numbering and Acknowledging ... On any connection, the iSCSI initiator MUST send the commands in increasing order of CmdSN, except for commands that are retransmitted due to digest error recovery and connection recovery. (From draft-chadalapaka-command-ordering-00.txt) 3.3 Ordered command delivery 3.3.1 Issues There has been a lot of debate on this particular aspect in the IPS WG. Most of the debate was centered on two specific questions - ... b) Should [iSCSI] require initiators and targets to enforce command ordering? ... The final resolution of b) in section 3.3.1 by the iSCSI protocol designers was in favor of not requiring the initiators to use com- mand ordering always. This resolution is reflected in dropping the ACA requirement on the initiators, and allowing ABORT TASK TMF to plug command holes etc. The net result can be discerned by a care- ful reader of [iSCSI] - the onus of command ordering is on the iSCSI targets, while the initiators may or may not use command ordering. 2) I think the following text from section 6 implies that implementations should not comply with iSCSI, is this the authors intent as well? If so wouldn't this lead to interoperability problems? "In general, command ordering is automatically enforced if targets and initiators comply with the iSCSI specification. However, here are certain things for the iSCSI initiators and targets to take note of...." I would appreciate any comments--they would greatly help me with my work. Thanks, Aaron
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