Re: About F-bit in ISCSI Scsi command PDU

[Bill Studenmund <wrstuden@wasabisystems.com>]

On Tue, 13 Aug 2002, Prashanth.C.A. Shetty wrote:

> Hello All,
>     As per the draft definition of F-bit explained in
> the iSCSI SCSI command PDU section..."F-bit should be
> set to 1 when no unsolicited data follow the command
> PDU".

Where did you see that text?

In draft 15, section 9.3.1, I see:

(F) is set to 1 when no unsolicited SCSI Data-Out PDUs follow this PDU.

>     My interpretation of the above statement is:
>     F-bit in the command PDU is to be set to 1 by the
> initiator only if solicited data needs to be sent to
> the Target and should be zero for Unsolicited data
> transfer.
>     My question:
>     If I need to send only immediate
> data:..[dataxferlen <=
> MaxRecvPduLen,InitalR2t=True,ImmediateData=True]....What
> should be the F-bit set to????.

The text quoted above clarifies that F only applies to unsolicited data
PDUs, not immediate data.

>     Should it be set to ZERO[because IMMEDIATE DATA
> ONLY[InitialR2t=True,ImmediateData=True] falls as one
> of unsolicited data transfer type] or should it be set
> to ONE[because no unsolicited data follows the command
> PDU]????

One, as there are no unsolicited Data-Out PDUs.

Note also that just because you negotiated ImmediateData=Yes, and it's
probably better to (saves a data PDU), you don't HAVE to send any. You
just can.

Take care,

Bill