RE: iSCSI: Iterating long text responses

[Robert Snively <rsnively@Brocade.COM>]

I have looked over the options for iterating long text
responses.  In the context of SCSI driver stacks, #5 is 
a familiar behavior that could be applied very easily
to the text commands.  If anyone was interested, it could
even be extended to a future SCSI command within the SCSI 
command set.  I favor #5.

Bob Snively                        e-mail:    rsnively@brocade.com
Brocade Communications Systems     phone:  408 487 8135
1745 Technology Drive
San Jose, CA 95110



>  
>  5. Do #4, but allow the initiator to specify the amount of data
>     it is willing to accept:
>  
>     I->T  Text Command (F bit set, AcceptResponseLength=4096)
>     T->I  Text Response (first PDU, F bit set, 
>  TotalResponseLength=12288)
>  
>     In the above example, we have created a new text command field:
>  
>        AcceptResponseLength
>  
>     And in the text response PDU:
>  
>        TotalResponseLength
>  
>     The initiator indicated it was willing to accept a 4k response.
>     The target returned the first 4k in the text response, but set
>     the F bit since it was at its limit.  It also returned a
>     TotalResponseLength field.  Since this was greater than the
>     AcceptResponseLength, the initiator knows the amount of buffer
>     space it will need to get the full response.  It can then choose
>     whether it will re-send the command, and if so, can give it a
>     large enough response length:
>  
>     I->T  Text Command (F bit set, AcceptResponseLength=12288)
>     T->I  Text Response (first PDU, F bit clear)
>     T->I  Text Response (next PDU, F bit clear)
>     T->I  Text Response (last PDU, F bit set, 
>  TotalResponseLength=12288)
>  
>     Note that most initiators will probably send an 
>  AcceptResponseLength
>     of the largest response they would normally accept, and that most
>     target responses will fit in one or a few PDUs anyway.