RE: ips : Is FirstBurstSize valid when InitialR2T=yes ?

["Julian Satran" <Julian_Satran@il.ibm.com>]

Pat,

You are fighting a very old war!
The mail you are answering is dated February 2002!

Julo

"THALER,PAT (A-Roseville,ex1)" <pat_thaler@agilent.com> Sent by: owner-ips@ece.cmu.edu 06/14/2002 08:23 PM Please respond to "THALER,PAT (A-Roseville,ex1)"

To:        Santosh Rao <santoshr@cup.hp.com>, Eddy Quicksall <Eddy_Quicksall@ivivity.com>         cc:        IPS Reflector <ips@ece.cmu.edu>         Subject:        RE: ips : Is FirstBurstSize valid when InitialR2T=yes ?

Santosh,

I strongly disagree. There is no reason that FirstBurstSize should be 0 or any other particular value if InitalR2T = yes and ImmediateData=No. It won't be used in that case so it is fine for it to remain at the default of 64k or any other allowed value. The only requirment is that the target should respond with a valid value (one that is less than the offerred value and less than MaxBurstSize) because simple-minded login code on the Initiator may check that the value follows the rules even though other keys make the value unused. The target could also respond with Irrelevant.

Pat

-----Original Message-----
From: Santosh Rao [mailto:santoshr@cup.hp.com]
Sent: Wednesday, February 06, 2002 1:33 PM
To: Eddy Quicksall
Cc: IPS Reflector
Subject: Re: ips : Is FirstBurstSize valid when InitialR2T=yes ?



I think this needs changing then. There's no reason the following
should'nt be allowed :

I -> T :
                 InitialR2T=no
                 ImmediateData=yes
                 FirstBurstSize=65536

T -> I :
                 InitialR2T=yes
                 ImmediateData=no
                 FirstBurstSize=0

Julian :
Can we change the allowed valid range for FirstBurstSize from :

FirstBurstSize=<number-512-to-(2**24-1)>

to :

FirstBurstSize=<number-0-to-(2**24-1)>


- Santosh


Eddy Quicksall wrote:
> 
> Draft 10 says:
> 
> FirstBurstSize=<number-512-to-(2**24-1)>
> 
> So that means you can't send a 0, doesn't it?
> 
> Eddy
> 
> -----Original Message-----
> From: Santosh Rao [mailto:santoshr@cup.hp.com]
> Sent: Wednesday, February 06, 2002 3:01 PM
> To: Fischer, Michael
> Cc: 'Eddy Quicksall'; IPS Reflector
> Subject: Re: ips : Is FirstBurstSize valid when InitialR2T=yes ?
> 
> IMO, the FirstBurstSize key value negotiated during login is a don't
> care if *BOTH* immediate data and un-solicited data have been disabled.
> 
> However, if the target knows up-front that it does not support either
> immediate or un-solcited and it receives the key FirstBurstSize during
> login negotiation, it should return a 0 value as the result of the
> negotiation for FirstBurstSize.
> 
> (Note that the special semantics of 0 implying no limit is no longer
> true for FirstBurstSize and hence, the target can just return 0 iff both
> immediata data and un-solicited data are disabled in login negotiation.)
> 
> - Santosh
> 
> "Fischer, Michael" wrote:
> >
> > What if the sequence is as follows:
> >
> > I->T    FirstBurstSize=512; T=0; NSG=CSG;
> > T->I    FirstBurstSize=512; T=0; NSG=CSG;
> > I->T    InitialR2T=no, ImmediateData=no; T=1; NSG=FULL
> >
> > If the target does not support InitialR2T=no..  Does login now fail?
> There
> > does not seem to be a way for the target to say that it requires R2T.  Why
> > did the Initiator send FirstBurstSize if it was setting InitialR2T to no?
> > There is no negotiation with an AND function.
> >
> > Michael Fischer
> >
> > -----Original Message-----
> > From: Eddy Quicksall [mailto:Eddy_Quicksall@ivivity.com]
> > Sent: Wednesday, February 06, 2002 9:47 AM
> > To: Santosh Rao; IPS Reflector
> > Subject: RE: ips : Is FirstBurstSize valid when InitialR2T=yes ?
> >
> > That is how I am interpreting it.
> >
> > BTW: How about this one ...
> >
> > I->T FirstBurstSize=512, InitialR2T=no, ImmediateData=no
> >
> > If the target does not support InitialR2T=no, how should it respond to
> > FirstBurstSize?
> >
> > Should the target do this (for draft >= 9)?
> >
> > T->I FirstBurstSize=irrelevant, InitialR2T=yes, ImmediateData=no
> >
> > Eddy
> >
> > -----Original Message-----
> > From: Santosh Rao [mailto:santoshr@cup.hp.com]
> > Sent: Tuesday, February 05, 2002 2:56 PM
> > To: IPS Reflector
> > Subject: ips : Is FirstBurstSize valid when InitialR2T=yes ?
> >
> > Hello,
> >
> > Can someone clarify if the login key FirstBurstSize is valid when :
> > InitialR2T=yes  and ImmediateData=yes ?
> >
> > i.e. if immediate data is enabled and un-solicited data is disabled
> > during login negotiation, is the value of FirstBurstSize received in the
> > login response to be interpreted ?
> >
> > My current understanding is that FirstBurstSize is inclusive of the
> > immediate data portion, and so, if immediate data is enabled, but
> > un-solicited data is disabled, then, FirstBurstSize *must* be valid and
> > must be <= DataPDULength. (after rev 09, it would be <=
> > (MaxRecvPDULength - the header components size)).
> >
> > For example, a target implementation may offer a FirstBurstSize <
> > DataPDULength, in which case, the immediate data size is the
> > MIN(DataPDULength, FirstBurstSize, bytes_to_send).
> >
> > Can someone clarify if this is a correct interpretation or set me right
> > on this ?
> >
> > Thanks,
> > Santosh


-- 
##################################
Santosh Rao
Software Design Engineer,
HP-UX iSCSI Driver Team,
Hewlett Packard, Cupertino.
email : santoshr@cup.hp.com
Phone : 408-447-3751
##################################