iSCSI:Negotiating a maximum SCSI data phase

["Alison and Ken Thomas" <kenali2000@hotmail.com>]

Evening all,

One parameter which is trivial to specify but would make a big
difference to the target is to be able to negotiate the maximum
SCSI data phase any individual SCSI Command PDU will have associated
with it. The suggested words are:

     35 MaxSCSIDataPhase

        Use: LO
        Who can send: Initiator and Target

        MaxSCSIDataPhase=<number-from-0-to-4294967295>

        Default is 4294967295.

        Initiator and target negotiate the maximum number of bytes
        that can be specified in the Expected Data Transfer Length
        field of a SCSI Command PDU.  The lower of the 2 numbers
        is selected.


Basically, the default case is no change to the status quo, but in
the field of resource management, this assists the target by knowing
what may be thrown at it.

It may be beneficial for initiators too as one day when 1GB transfers
are the norm, a legacy target can advertise its age and indicate that it
stands not a snowflake's chance in Australia of actually servicing such
requests.

Cheers,

Ken Sandars
ksandars@eurologic.com
Eurologic Systems
+44 117 930 9616



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