99-231r0 - EXTENDED COPY and Abort Task Management Functions
Ericson, George
gericson at clariion.com
Mon Sep 13 10:03:51 PDT 1999
* From the T10 Reflector (t10 at t10.org), posted by:
* "Ericson, George" <gericson at clariion.com>
*
Copy Manager Devices are modeled as an independent device that translates
copy requests to read and write requests to other devices. This suggests
some changes to SAM2 as well as SPC2.
Proposal:
In addition to modifications to SPC-2. Modify the Abort Task description in
SAM-2 to support devices which issue commands to other devices. This would
implicitely cover the Copy Manager.
--------------------------------------------------
Insert before last paragraph of SAM2.11, section 6.1
Before returning a FUNCTION COMPLETE response the logical unit must wait for
a FUNCTION COMPLETE response from all outstanding Task requests that have
been issued to other devices pursuant to the execution of this Task. To
expedite those responses, the Device Server may issue Abort Task requests to
any or all of those outstanding Task requests. In that case, the FUNCTION
COMPLETE returned by the Abort Task request will satisfy the requirement of
a FUNCTION COMPLETE from the associated Task request.
----------------------------------------------------
George
-----Original Message-----
From: Ralph Weber [mailto:ralphoweber at CompuServe.COM]
Sent: Saturday, August 21, 1999 9:12 AM
To: T10, Reflector
Subject: 99-231r0 - EXTENDED COPY and Abort Task Management Functions
* From the T10 Reflector (t10 at t10.org), posted by:
* Ralph Weber <ralphoweber at compuserve.com>
*
A proposal for consideration at the September meetings has
been placed on the T10 FTP site as:
< ftp://ftp.t10.org/t10/document.99/99-231r0.pdf >
The text of the proposal is included below. However, the PDF
contains text formatting that cannot be represented in ASCII plain
text. Please refer to the PDF if the information below catches your
interest.
Doc: T10/99-231r0
Date: 18 August 1999
To: T10 Technical Committee
From: Ralph Weber, LSI Logic Alternate Member of T10
Subj: EXTENDED COPY and Abort Task Management Functions
The ABORT TASK, ABORT TASK SET, and CLEAR TASK SET task management
functions may cause an EXTENDED COPY command to be terminated
prematurely. When this occurs as a result of a persistent
reservations PREEMPT AND ABORT service action it is critical that the
copy manager cease all data transfers as part of completing the ABORT
TASK SET operation described in list entry b) in 5.3.2.5.3 (SPC-2 rev
11).
Two alternatives are proposed for instantiating this requirement in
SPC-2. Two alternatives are necessary because task management
functions have less than perfectly defined completion notification
requirements, and the completion notification of the ABORT TASK SET
task management function is a key concept in one of the alternatives.
Alternative I
Since initiators using the ABORT TASK SET, et. al. task management
functions to prematurely terminate an EXTENDED COPY command probably
desire the same behavior as required by persistent reservations,
alternative I proposes to state the requirement as a requirement on
the copy manager for task management function support. This would be
accomplished by adding a new clause to the EXTENDED COPY command
definition.
Pros
This alternative places the requirement text in the definition of the
EXTENDED COPY command, which is where developers of copy manager
functions are most likely to look for special requirements for their
software.
Cons
The mechanism by which an ABORT TASK SET task management function
indicates its completion had a weak definition, especially for some
SCSI protocols. Thus, the statement '... before allowing the device
server to complete the task management function' is more open to
interpretation than might be desirable.
Specific Proposal
Add the following as clause 7.4.3 and renumber subsequent clauses as
necessary.
7.4.3 Abort task management functions
When a device server processes an ABORT TASK, ABORT TASK SET, or
CLEAR TASK SET task management function that terminates an
EXTENDED COPY command, the copy manager shall ensure that all
commands it has issued pursuant to the EXENDED COPY command have
been terminated and are no longer transferring data before
allowing the device server to complete the task management
function. This requirement shall also apply to the processing
the PREEMPT AND ABORT service action on the PERSISTENT RESERVE
OUT command as described in 5.3.2.5.3.
Alternative II
State the requirement directly in the 5.3.2.5.3 description of the
PREEMPT AND ABORT service action.
Pros
This alternative leaves no confusion as to the requirements for the
PREEMPT AND ABORT service action.
Cons
The defined behavior for the ABORT TASK SET, et. al. task management
functions is ambiguous, although no worse so than for the COPY
command today. Developers focused on the definition of the EXTENDED
COPY command may miss the requirement.
Specific Proposal
Modify list b) in clause 5.3.2.5.3 to read as follows (new text
underlined in the PDF):
b) Every task from all preempted initiators shall be terminated
as if an ABORT TASK SET task management function had been
performed by each of the preempted initiators. If a terminated
task is a COPY or EXTENDED COPY command, all commands and data
transfers generated by the command shall be terminated before the
ABORT TASK SET task management function is considered completed.
After the ABORT TASK SET function has completed, all new tasks
are subject to the persistent reservation restrictions
established by the preempting initiator;
*
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