00-203r0 - Describing AEN in the Processor Device Model

Ralph Weber ralphoweber at CompuServe.COM
Sun Apr 2 16:06:05 PDT 2000

* From the T10 Reflector (t10 at t10.org), posted by:
* Ralph Weber <ralphoweber at compuserve.com>
A proposal for consideration at the May meetings has been placed
on the T10 FTP site as:

< ftp://ftp.t10.org/t10/document.00/00-203r0.pdf >

The text of the proposal is as follows. Bold text has been removed
for ASCII text compatibility.  See the PDF for a fully formatted
presentation of the proposal.

Doc:  T10/00-203r0
Date: 2 April 2000
To:   T10 Technical Committee
From: Ralph Weber
Subj: Describing AEN in the Processor Device Model

During the development of SAM and SPC, we defined AER (Asynchronous
Event Reporting) as the general capability to report asynchronous
events as they happen and modeled it in SAM.  Appropriate name
changes (from AEN to AER) also were made at that time.  The intention
(as I remember it) was that AEN (Asynchronous Event Notification)
would be defined as a specific implementation of AER that relies on
using the host as a processor device to deliver AER data as the event
happen.  I also believe that there was an intention to tie AEN and
AER together by appropriate text in SPC.

I’ve noticed that the SPC-2 processor device model does not contain
any text that ties the knot between AEN and AER, neither does any
other part of SPC-2.  This proposal attempts to cleanup what may be
the very very old action item of describing the relationship between
AEN and AER.

Proposals for Specific Changes in SPC-2

Add the following definition:

3.1.x Asynchronous Event Notification: A specific implementation of
asynchronous event reporting that employs the processor device model
(see 6.2).

Add the following acronym:

AEN Asynchronous Event Notification (see 3.1.x)

Add the following clause heading and place all the text currently in
clause 6 in the new clause:

6.1 Processor Model Overview

Add the following clause:

6.2 Asynchronous Event Notification Model

Asynchronous event notification is a specific implementation of
asynchronous event reporting (see SAM-2) used by some protocols.
When the AEN model is used and an initiator enables asynchronous
event reports using the Control mode page (see 8.3.4), the initiator
is required to become a processor device model target when
asynchronous event reports are delivered.

Under AEN, delivery of an asynchronous event report occurs as

  1) The SCSI device with an event to report (a target that has been
     enabled to send AEN model AER reports via the Control mode page)
     becomes an initiator and sends a SEND command with the AER bit
     set (see 9.2); and
  2) The SCSI device to which the AEN report is sent (the initiator
     that enabled the AEN model AER reports by sending a MODE SELECT
     command with appropriate settings in the Control mode page)
     becomes a target to receive the SEND command with AER bit set
     and the AER sense data delivered in the Data-In buffer.

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