Date:   September 04, 1991                      Document:  X3T9.2/91-148 Rev 0

To:     ANSI X3T9.2 Committee (SCSI)

From:   Jeffrey L. Williams (HP)

Subject: AEN via Request Sense

Proposal:

There currently does not exist a method of obtaining Asynchronous Event
Notifications for an initiator that does not support AEN.  A polling method
for obtaining AE data would enable an initiator to obtain this data 
without the supporting AENs.  This proposal deals with changes to the 
Request Sense Command and Inquiry Command which would allow for AE polling.


Requested Change:


Section 7.2.5.1  

+-------+-------+-------+-------+-------+-------+-------+-------+-------+
|Bit    |   7   |   6   |   5   |   4   |   3   |   2   |   1   |   0   |
|Byte   |       |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+-------+
|   0   |  Peripheral Qualifier |        Peripheral Device Type         |
+-------+-------+---------------+---------------------------------------+
|   1   |  RMB  |           Device-Type Modofier                        |
+-------+-------+-------+-----------------------+-----------------------+
|   2   |  ISO Version  |     ECMA Version      | ANSI-Approved Version |
+-------+-------+-------+-------+-------+-------+-----------------------+
|   3   | AENC  |TrmIOP | AENP  | Rsvd  |    Response Data Format       |
+-------+-------+-------+-------+-------+-------------------------------+
|       |                                                               |
| 4 -n  |   UNCHANGED                                                   |
|       |                                                               |
+-------+---------------------------------------------------------------+


The asynchronous event notification polling (AENP) bit of one indicates 
that that the device is capable of being polled for asynchronous event 
notifications.  An AENP bit of zero indicates that the device does not 
support polling for asynchronous event notifications.

Section 7.2.14   Request Sense Command

+-------+-------+-------+-------+-------+-------+-------+-------+-------+
|Bit    |   7   |   6   |   5   |   4   |   3   |   2   |   1   |   0   |
|Byte   |       |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+-------+
|   0   |                Operation Code (03h)                           |
+-------+-----------------------+-------+-------+-----------------------+
|   1   | Logical Unit Number   |          Reserved             | AENR  |
+-------+-----------------------+-------+-------+-----------------------+
|   2   |                         Reserved                              |
+-------+---------------------------------------------------------------+
|   3   |                         Reserved                              |
+-------+---------------------------------------------------------------+
|   4   |                     Allocation Length                         |
+-------+---------------------------------------------------------------+
|   5   |                          Control                              |
+-------+---------------------------------------------------------------+

The Asynchronous Event Notification Request bit (AENR) is optional.  An 
AENR bit of one indicates that the initiator is requesting the next pending
asynchronous event.  If no asynchronous events are pending, the target 
returns sense data with the sense key set to No Sense and additional sense
code set to No Additional Sense.