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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: iSCSI: Target -> Initiator SNACK?Initiator finds out by timeout and follows-up with a retry. Chapter 6 has it all and details are in the appendix. Julo
I'm having difficulty figuring out how a target handles CmdSN gaps it detects (due to lost PDU, digest errors, etc.) The draft reads like it is not a Target issue and it's up to the initiator to recover from this. How are both the target and initiator are supposed to handle this situation? Since the target cannot advance beyond it's expected next CmdSN (2.2.2.1), how does the initiator detect the gap? Through a timeout? A target initiated Nop-In? Thanks! 6.1.1 Usage of Retry By resending the same iSCSI command PDU ("retry") in the absence of a command acknowledgement or response, an initiator attempts to "plug" (what it thinks are) the discontinuities in CmdSN ordering on the tar- get end. Discarded command PDUs, due to digest errors, may have cre- ated these discontinuities. Retry MUST NOT be used for reasons other than plugging command sequence gaps. In particular, all PDU retransmission (for data, or status) requests for a currently allegiant command in progress must be conveyed to the target using only the SNACK mechanism already described. This, however, does not constitute a requirement on initi- ators to use SNACK.
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