RE: Target Behavior Clarifications

<[email protected]> wrote on 18/04/2006 21:10:46:

> Based on the responses from Bill and Julian this is what I have:
> 
> 1) What should the behavior of a target be if it receives a PDU on a
> connection, larger than what it declared with MaxRecvDataSegmentLength:
> - If the PDU is part of a SCSI command? 
> <JC> I will drop the connection and terminate the task and generate 
> a UA with ASC/ASCQ value of 47h/7Fh - "SOME COMMANDS CLEARED BY 
> ISCSI PROTOCOL EVENT". If this is only connection in the session 
> then I generate a UA (06/29/00).
> - If the PDU is part of a login?
> <JC> I will drop the connection. Agreed that the default value of 8K
> should be supported since login is not complete.
> 
> 2) What should the target behavior be if the initiator sends it moredata 
than
> MaxBurstLength?
> 3) What should the target behavior be if the initiator sends more data 
than 
> FirstBurstLength?
> <JC> I have two options here: 
> 
> a)    As per the spec: The target reports the "Incorrect amount of 
> data" condition if during data output the total data length to 
> output is greater than FirstBurstLength and the initiator sent 
> unsolicited non-immediate data but the total amount of unsolicited 
> data is different than FirstBurstLength. The target reports the same
> error when the amount of data sent as a reply to an R2T does not 
> match the amount requested. (0B/0C/0D ? Write Error, Incorrect 
> Amount of Data). This should work.
> 
> The only issue here is that the definition of the sense code does 
> not match the definition in SPC-3 which says 0Ch 0Dh - WRITE ERROR -
> NOT ENOUGH UNSOLICITED DATA), which is not quite what the iSCSI says.
> 
> 
> b)    Treat this as a really bad error and assume that I have an 
> initiator that does not play well and drop the session and kill the 
command.
> 
That's what I would do too 
> 
> I am leaning towards (b). Help!!! Suggestions/Comments/Discussion.
> 
> Thanks, 
> 
> Jacob Cherian 
> Dell Inc. 
> Ph: (512) 723 3247 
> 
> From: William Studenmund [mailto:[email protected]] 
> Sent: Tuesday, April 18, 2006 12:33 PM
> To: Cherian, Jacob
> Cc: [email protected]
> Subject: Re: [Ips] Target Behavior Clarifications
> 
> On Apr 17, 2006, at 2:48 PM, <[email protected]> 
<[email protected]
> > wrote:
> 

> A couple of quick questions?
> 1) What should the behavior of a target be if it receives a PDU on a
> connection, larger than what it declared with MaxRecvDataSegmentLength:
> - If the PDU is part of a SCSI command? 
> - If the PDU is part of a login?
> 
> Drop the connection. Note, the session may still stick around as 
> part of recovery processing.
> 
> Also, during login (before FFP), the MaxRecvDataSegmentLength in 
> force is 8k, regardless of announced values.
> 

> 2) What should the target behaviour be if the initiator sends it 
> more data than MaxBurstLength?
> 3) What should the target behavior be if the initiator sends more data 
than 
> FirstBurstLength?
> There are specific sense and ASC/Q values for these errors.
> 
> These are treated as SCSI errors 1) because you have to give some 
> explanation for why you killed the SCSI task, and 2) because it is 
> not obvious which PDU in the burst was "too much." While you might 
> want to say it was the last one, that isn't necessarily true.
> 
> Note also that to trigger these errors, all the data placement had 
> to stay within the TTT bounds and you have to be in 
> DataPDUInOrder=No. That's the only way you can really write the same
> area twice. Most other errors involved in sending too much data in a
> burst would trigger an iSCSI protocol error by placing data outside 
> the bounds of the TTT.
> 
> Take care,
> 
> Bill_______________________________________________
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