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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: iSCSI: Plugging holes in CmdSNLakshmi, Comments below. -- Mallikarjun Mallikarjun Chadalapaka Networked Storage Architecture Network Storage Solutions Hewlett-Packard MS 5668 Roseville CA 95747 cbm@rose.hp.com ----- Original Message ----- From: "Lakshmi Ramasubramanian" <nramas@windows.microsoft.com> To: "Julian Satran" <Julian_Satran@il.ibm.com>; <ips@ece.cmu.edu> Sent: Friday, May 30, 2003 12:59 PM Subject: iSCSI: Plugging holes in CmdSN >If the target detects data digest error in a PDU, >and sends Reject the initiator I assume you mean the SCSI command PDU above. > > * MAY retry the command with the same CmdSN, TaskTag, etc. > > * Or, Send a Task Mgmt command to ABORT TASK that task. > >Target will not advance ExpCmdSN until initiator does something >to clear the rejected command. Yes, one of the two must happen (or the session drop, of course). > >But, can the initiator send a Task Mgmt command with function >LU Reset (instead of ABORT TASK) as IMMEDIATE command? The initiator may. Because the LU Reset is an immediate command, it will be processed by the iSCSI layer and then the SCSI layer and an LU Reset action will result. >Should >the target then clear the rejected command and any command that >was received after that? And, advance the ExpCmdSN so that initiator >can proceed with that session? I am not sure what you mean by "clear the rejected command". As for advancing ExpCmdSN, I don't think that is the legal behavior. Unless the target has a RefCmdSN to plug a hole, it cannot plug a CmdSN hole. And only the Abort Task TMF has the RefCmdSN. The iSCSI layer on target cannot afford to simply plug all the CmdSN holes with an LU Reset because there may be commands destined to other LUs already in the CmdSN reordering queue. Also, the iSCSI layer on the target does not look at the LUN field of each task - as a design rule.
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