FW: FW: Question about the Ignore Wide Residue message

Jeff Williams jlw at hpbs1506.boi.hp.com
Wed Jun 8 08:15:50 PDT 1994

Date:    06 Jun 94 14:58:00 BST

>      2. In what commands does the target send this message to the 
>      initiator?  

The only time that an IWR message is needed is when an initiator requests
the truncation of data at an odd boundary.  For example, a Request Sense
command with an allocation length of 13 bytes.  We have decided that we
will never send an IWR since it is pretty much useless.  In the case 
above, we would send 14 *valid* sense data bytes without the IWR.  So if
the initiator was expecting, and counting on, only 13 bytes but got 14 
since there was no IWR, there would be problems.  Otherwise, everything 
works fine.

Also, there are no cases I can think of where an allocation length of
0xff would be truncated by the target at an odd boundary.  All commands
return an even amount of data unless specifically told to truncate.

Jeffrey L. Williams                                HP TelNet: 396-5030
Disk Controllers Lab             	 Telephone: (1) (208) 396-5030
Disk Memory Division                     Facsimile: (1) (208) 396-6858
Hewlett-Packard Co.                    ARPANET: jlw at hpdmd48.boi.hp.com

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