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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: iSCSI: cmd_sn management on rejected PDUsJoseph, Refer section 7.2 of rev10 draft for the answer to this question. Now, on to your question - >Should the target wait for the initiator to 'fill the hole' >by issuing some other command with cmd_sn=37? Generally yes - since the target treats it no different from an unreceived PDU. Specifically, the regular operational ErrorRecoveryLevel expectations apply to recover the situation you describe. -- Mallikarjun Mallikarjun Chadalapaka Networked Storage Architecture Network Storage Solutions Organization Hewlett-Packard MS 5668 Roseville CA 95747 ----- Original Message ----- From: Pittman, Joseph To: 'ips@ece.cmu.edu' Sent: Thursday, February 14, 2002 7:04 AM Subject: iSCSI: cmd_sn management on rejected PDUs I have a question about sequence number management when command PDUs are rejected. If an initiator sends a non-immediate command PDU which the target rejects, does this command consume a cmd_sn? For example, consider this case: - initiator sends a non-immediate text request with a non-zero target transfer tag, sequence number 37 - target looks up the target transfer tag, doesn't recognize it, and generates a reject/UNKNOWN_TT_TAG message Should the next command PDU sent by initiator use cmd_sn=37 or cmd_sn=38? 2 follow-up questions: IF the rejected PDU IS supposed to consume a cmd_sn, then what are the rules regarding how badly a PDU BHS may be mangled before it can be considered worthy of consuming a cmd_sn? That is, should a PDU BHS with the expected cmd_sn and I-bit == 0, but containing an otherwise random stream of bytes, consume a cmd_sn? And what if the header digest is incorrect? IF the rejected PDU is NOT supposed to consume a cmd_sn (i.e. next command PDU should be cmd_sn=37), then what is supposed to happen in the following case: - target supports command window size of 4 - initiator sends a non-immediate text request with a non-zero target transfer tag, sequence number 37 - initiator sends three more non-immediate commands with cmd_sn 38, 39, and 40 - target rejects cmd 37 In this case, cmds 38, 39, and 40 have arrived 'out of order'. Should the target wait for the initiator to 'fill the hole' by issuing some other command with cmd_sn=37? Thanks in advance for any spec interpretation or advice. -- Joe Pittman jpittman@netapp.com
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