Re: ISCSI: need to fix handling of partial data transfers

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

Device operation is not in the iSCSI domain.  You can find the information
you need in SCSI.
It comes complete with device type, capabilities, alignment required(if
any), block sizes and much more (enough to fill many pages for every device
class).  If you want the information you require just ask for it by SCSI
means.
A perusal of the SCSI standards for several classes of devices might help.

Julo


                                                                                                         
                      Paul Koning                                                                        
                      <ni1d@arrl.net>          To:       Julian Satran/Haifa/IBM@IBMIL                   
                      Sent by:                 cc:       ips@ece.cmu.edu                                 
                      owner-ips@ece.cmu        Subject:  Re: ISCSI: need to fix handling of partial data 
                      .edu                      transfers                                                
                                                                                                         
                                                                                                         
                      16-03-02 18:24                                                                     
                      Please respond to                                                                  
                      Paul Koning                                                                        
                                                                                                         
                                                                                                         



Excerpt of message (sent 16 March 2002) by Julian Satran:
>
> Paul,
>
> We have different opinions on basics.
> If I enter into an appliance shop and ask for a bottle of milk - I get an
> "error message".
> It may fall in one of two categories:
>
>    "protocol error" (in humanes - "you are an idiot")
>    "we don't keep milk"
>
>
> I agreed that the first was not nice and I will change it.
> But there are errors from which you have no recovery - the devices can't
> work with each other.

I think we're actually pretty much in agreement here.

My point is this:

Right now the spec says "you can ask for milk in an appliance store,
but the shopkeeper is allowed to tell you 'no'".  I'm proposing to say
"you cannot ask for milk in an appliance store".

The outcome is the same either way: the devices discover that they
can't talk to each other.  But the second rule is simpler.

So that's why I proposed to make the rule "you must answer with
exactly the data length asked for (R2T) or negotiated (unsolicited
data length)".

     paul