RE: ISCSI: Unsolicited data in draft v12

["BURBRIDGE,MATTHEW (HP-UnitedKingdom,ex2)" <matthew_burbridge@hp.com>]

I must express my concern on this issue.  From a target point of view once
it has negoiated the use of unsolicited data it has to allocate buffer space
for that unsolicited data.  Now depending on the various parameters this may
be a sizeable chunk of valuable resources which it is making available.  Now
if the decision to use unsolicited data is being moved from a per session to
per task basis (which is what this change effectively does) then it puts an
awful lot of resource overhead on the target which may never be used.

For the reasons above I propose that we do not relax the v12 restriction and
keep it as:

"An iSCSI initiator MUST send as unsolicited data either the negotiated
amount or all the data if the total amount is less than the negotiated
amount for unsolicited data."

Matthew Burbridge
Principal Engineer
NSAS-Bristol
Hewlett Packard

-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
Sent: Monday, April 08, 2002 9:36 AM
To: Rod Harrison
Cc: ips@ece.cmu.edu; owner-ips@ece.cmu.edu
Subject: Re: ISCSI: Unsolicited data in draft v12



OK - Julo 


"Rod Harrison" <rod.harrison@windriver.com> 
Sent by: owner-ips@ece.cmu.edu 
08-04-02 14:52 
Please respond to "Rod Harrison" 
        
        To:        <ips@ece.cmu.edu> 
        cc:         
        Subject:        ISCSI: Unsolicited data in draft v12 

       



                I propose we slightly relax the new restriction in draft v12
that the
initiator MUST send the maximum permissible amount of unsolicited data. I
suggest we change the rule to allow the initiator to either send no
unsolicited data, or the maximum permissible.

                There is no difficulty for the target here since the lack of
unsolicited
data will be clearly indicated by a command PDU with F bit set and
dataSegLen=0. The target will have all the information it needs to
immediately issue R2Ts as appropriate.

                I believe the initiator should be able to make a policy
decision on which
individual commands should be sent with unsolicited data and which should
not.

                In draft 11.91 section 2.2.4 I suggest we change

"An iSCSI initiator MUST send as unsolicited data either the negotiated
amount or all the data if the total amount is less than the negotiated
amount for unsolicited data."

                to something like

"An iSCSI initiator MAY choose to send no unsolicited data with a command,
or if any unsolicited data is sent it MUST be either the negotiated amount
or all the data if the total amount is less than the negotiated amount for
unsolicited data."

                - Rod