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Subject: RE: iSCSI version 20 draft
Date: Wed, 22 Jan 2003 12:34:38 -0600
Message-ID: <78AF3C342AEAEF4BA33B35A8A15668C60296E7D9@cceexc17.americas.cpqcorp.net>
Thread-Topic: iSCSI version 20 draft
Thread-Index: AcLATNK4rZ6V/dVsTaeo6LUGAxknQQB963Zw
From: "Elliott, Robert (Server Storage)" <Elliott@hp.com>
To: <ips@ece.cmu.edu>
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Sorry to belabor this, but the wording about the affects of connection 
loss didn't end up like Mallikarjun's final recommendation.

Upon further discussion, we think this would be better:

If the tasks terminated in the above cases are SCSI tasks, they must 
be internally terminated as if with CHECK CONDITION
status. This enables ordering to be maintained correctly with respect
to commands on other connections when ACA is enabled. This enables 
ordering to be maintained correctly with respect to commands on other 
connections of the same I_T nexus when ACA is enabled (i.e., commands
waiting to be processed after those terminated are blocked due to
the ACA) - see [SAM-3] and [SPC-3].

After the tasks are terminated, the device server shall report a unit 
attention condition with an additional sense code of COMMANDS 
CLEARED BY TRANSPORT PROTOCOL EVENT on the next command processed on 
any connection for each affected I_T_L nexus. This enables ordering to 
be maintained correctly with respect to commands on other connections 
of the same I_T nexus when unit attention interlock is enabled (i.e., 
commands waiting to be processed after those terminated are blocked 
due to the unit attention interlock) - see [SAM-3] and [SPC-3].


The first paragraph explains why the "CHECK CONDITION" part is
important for the internally terminated tasks. If they were
allowed to terminate as if they had "GOOD" status, they wouldn't
invoke ACA.

The second paragraph explains the unit attention that must appear
on the next command on the wire (and lists the additional sense
code to use). This is not an additional sense code for an internal-only 
command status, so is appropriate for iSCSI to mention. We'll assign 
that code in SPC-3.


The text in iscsi-20 is:
6.5 Implicit termination of tasks
...
If the tasks terminated in the above cases a), b, c) and d)are
SCSI tasks, they must be internally terminated as if with
CHECK CONDITION status. This status is only meaningful for
appropriately handling the internal SCSI state and SCSI side
effects with respect to ordering because this status is never
communicated back as a terminating status to the initiator.
However additional actions may have to be taken at SCSI level
depending on the SCSI context as defined by the SCSI standards
(e.g., queued commands and ACA, UA for the next command on the
I_T nexus in cases a), b), and c) etc. - see [SAM] and [SPC3]).

10.14.5 Implicit termination of tasks
...
If the tasks terminated in any of the above cases are SCSI
tasks, they must be internally terminated as if with
CHECK CONDITION status. This status is only meaningful for
appropriately handling the internal SCSI state and SCSI side
effects with respect to ordering because this status is never
communicated back as a terminating status to the initiator.
However additional actions may have to be taken at SCSI level
depending on the SCSI context as defined by the SCSI standards
(e.g., queued commands and ACA, UA for the next command on the
I_T nexus in cases a), b), and c) etc. - see [SAM] and [SPC3]).

-- 
Rob Elliott, elliott@hp.com 
Hewlett-Packard Industry Standard Server Storage Advanced Technology 
https://ecardfile.com/id/RobElliott 


-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com] 
Sent: Sunday, January 19, 2003 11:52 PM
To: internet-drafts@ietf.org
Cc: ips@ece.cmu.edu; Allison Mankin
Subject: iSCSI version 20 draft


On behalf of the team of authors and as part of the IETF-IPS working
group 
I submit a draft for immediate publication. 

The text and pdf versions can be found at: 

http://www.haifa.il.ibm.com/satran/ips/draft-ietf-ips-iscsi-20.txt 
http://www.haifa.il.ibm.com/satran/ips/draft-ietf-ips-iscsi-20.pdf 

This version completely replaces: 

draft-ietf-ips-iscsi-19.txt and pdf 


The change marks are relative to version 19 and are clarifications
as requested by Steve Bellovin and typo fixes. 
All AD concerns and the "nits" where (hopefully) addressed. 

Julian Satran - IBM Research Laboratory at Haifa