RE: iSCSI SCSI command F bit questions

[pat_thaler@agilent.com]

A goal of having the unsolicited data feature is that it allows data to flow (in the unsolicited data out PDUs) during the round trip delay for the first R2T. To achieve this, the Target must know how much unsolicited data will be sent when it receives the SCSI command PDU so it knows where to start the range of the R2T. The set of options you list allows that. When the target receives the command PDU, it can tell by examination of that PDU whether the initiator has chosen 1, 2, 3 or 4 below.
 1. no unsolicited data 
 2. unsolicited data = immediate data length
 3 and 4. unsolicited data = FirstBurstLength or all the data, which ever is less.

Note that your terminology below is a little off - unsolicited data includes immediate data. If you want to specifically talk about the unsolicited data sent in data out PDUs, you need to say non-immediate unsolicited data.

Pat

-----Original Message-----
From: AClarke@attotech.com [mailto:AClarke@attotech.com]
Sent: Wednesday, April 09, 2003 6:59 AM
To: wrstuden@wasabisystems.com
Cc: ips@ece.cmu.edu
Subject: Re: iSCSI SCSI command F bit questions
<clip>
So for each unidirectional write command (with InitialR2T=No,
ImmediateData=Yes), the initiator can choose between:
    1. no immediate data and no unsolicited data (data-outs)
    2. immediate data and no unsolicited, immediate < FirstBurstLength
    3. no immediate data and unsolicited, unsolicited = FirstBurstLength
    4. immediate data and unsolicited data, sum = FirstBurstLength
Is this correct?

Why can't the initiator send less than FirstBurstLength of unsolicited
using a data-out with F bit set?
If we are acting as if an R2T was sent, section 10.8 states "a target MAY
choose to Reject that PDU with "Protocol error" reason code."