RE: iSCSI: Clarification (again) for Task Management Commands

["Julian Satran" <Julian_Satran@il.ibm.com>]

David,

I think that readers will want to consider 9.4 as an  implementation 
alternative.

Julo




Black_David@emc.com
Sent by: owner-ips@ece.cmu.edu
10-11-01 04:53
Please respond to Black_David

 
        To:     somesh_gupta@silverbacksystems.com, ips@ece.cmu.edu
        cc: 
        Subject:        RE: iSCSI: Clarification (again) for Task Management Commands

 

Somesh,

The language in question reflects fairly direct requirements
language to be found in SAM-2's description of SCSI Task Management.
FCP goes to serious lengths with FC sequence aborts to make sure
this behaves as required.

For iSCSI, if responses to the aborted commands show up unexpectedly,
they have to be discarded.  How the Initiator keeps track of that
is the Initiator's problem - keeping track of the CmdSN of the
Abort Task Set may be useful.

--David
---------------------------------------------------
David L. Black, Senior Technologist
EMC Corporation, 42 South St., Hopkinton, MA  01748
+1 (508) 435-1000 x75140     FAX: +1 (508) 497-8500
black_david@emc.com       Mobile: +1 (978) 394-7754
---------------------------------------------------

> -----Original Message-----
> From: Somesh Gupta [mailto:somesh_gupta@silverbacksystems.com]
> Sent: Friday, November 09, 2001 4:55 PM
> To: IPS
> Subject: iSCSI: Clarification (again) for Task Management Commands
> 
> 
> Resend to add iSCSI tag. Sorry for missing it.
> 
> On page 67 of the 8-92.txt draft (section 3.5.1), it
> says
> 
> "For all the tasks covered by the task 
> management response (i.e., with CmdSN not higher than the task 
> management command CmdSN), additional responses MUST NOT be delivered 
> to the SCSI layer after the task management response."
> 
> If there is a multiple connection session,
> a status for a command impacted by the task
> management command (say ABORT TASK SET) could
> be stuck in the pipe on one connection, while
> the ABORT TASK SET completes on another
> connection.
> 
> How does the initiator iSCSI enforce the rule above?
> Seems to be the equivalent of sending the impacted
> commands on other connections in a zombie state,
> and not having a very good idea of how to get out.
> 
> Similarly Section 9.4 provides additional rules,
> but seems to leave a hole open with regards to
> status already in flight on other connections.
> 
> Any clarifications would be appreciated.
> 
> Somesh
>