Re: iSCSI - changes - PDULength and related

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

Some framing mechanisms (defined by other standards) work well with PDU
length not exceeding path MTU.
This may be suboptimal (and I assume will be seldomness in use) but may
help get things going.

Julo

----- Forwarded by Julian Satran/Haifa/IBM on 20-10-01 23:58 -----
                                                                                        
                    Paul Koning                                                         
                    <pkoning@jlc.n       To:     Julian Satran/Haifa/IBM@IBMIL          
                    et>                  cc:     ips@ece.cmu.edu                        
                                         Subject:     Re: iSCSI - changes - PDULength   
                    15-10-01 17:04        and related                                   
                    Please respond                                                      
                    to Paul Koning                                                      
                                                                                        
                                                                                        



Excerpt of message (sent 12 October 2001) by Julian Satran:
> ...
> In addition text request and response key+value strings are not required
to
> be confined to a single PDU (as we PDULength can be a low as 64 bytes!)
>
> Comments?

Why change the minimum value of PDULength (and the two burstsize
parameters)?  It used to be 512, which makes more sense, although even
that is rather small.  Allowing the length to be set to such tiny
values (like 64) adds a lot of complexity to the implementation to no
useful purpose.

I'd prefer to see a minimum around 1500, but if not, at least it
should not be reduced from the existing value of 512.

       paul

> ...
> 23 MaxRecvPDULength
>
> Use: All
> Who can send: Initiator and Target
>
> MaxRecvPDULength=<0|number-64-to-2**24>
> ...
> 24 MaxBurstSize
>
> Use: LO
> Who can send: Initiator and Target
>
> MaxBurstSize=<0|number-64-to-2**24>
>
> Default is 256 Kbytes.
>
> Initiator and target negotiate maximum SCSI data payload in bytes
> ...
> 25 FirstBurstSize
>
> Use: LO
> Who can send: Initiator and Target
>
> FirstBurstSize=<0|number-64-to-2**24>


----- Forwarded by Julian Satran/Haifa/IBM on 20-10-01 23:58 -----
                                                                                        
                    Paul Koning                                                         
                    <ni1d@arrl.net       To:     ips@ece.cmu.edu                        
                    >                    cc:                                            
                    Sent by:             Subject:     Re: iSCSI - changes - PDULength   
                    owner-ips@ece.        and related                                   
                    cmu.edu                                                             
                                                                                        
                                                                                        
                    18-10-01 17:54                                                      
                    Please respond                                                      
                    to Paul Koning                                                      
                                                                                        
                                                                                        



(((resending this, since the previous copy seems to have gone AWOL)))

Excerpt of message (sent 12 October 2001) by Julian Satran:
> ...
> In addition text request and response key+value strings are not required
to
> be confined to a single PDU (as we PDULength can be a low as 64 bytes!)
>
> Comments?

Why change the minimum value of PDULength (and the two burstsize
parameters)?  It used to be 512, which makes more sense, although even
that is rather small.  Allowing the length to be set to such tiny
values (like 64) adds a lot of complexity to the implementation to no
useful purpose.

I'd prefer to see a minimum around 1500, but if not, at least it
should not be reduced from the existing value of 512.

       paul

> ...
> 23 MaxRecvPDULength
>
> Use: All
> Who can send: Initiator and Target
>
> MaxRecvPDULength=<0|number-64-to-2**24>
> ...
> 24 MaxBurstSize
>
> Use: LO
> Who can send: Initiator and Target
>
> MaxBurstSize=<0|number-64-to-2**24>
>
> Default is 256 Kbytes.
>
> Initiator and target negotiate maximum SCSI data payload in bytes
> ...
> 25 FirstBurstSize
>
> Use: LO
> Who can send: Initiator and Target
>
> FirstBurstSize=<0|number-64-to-2**24>