RE: iSCSI: draft 7: Abort Task and RefCmdSN

[Black_David@emc.com]

ABORT TASK SET and CLEAR TASK SET also need the RefCmdSN to
indicate where in the stream of commands they were issued.
Julian - you probably need to revise your revised text to
take this into account.

--David

> -----Original Message-----
> From: Elliott, Robert [mailto:Robert.Elliott@compaq.com]
> Sent: Sunday, August 05, 2001 1:36 PM
> To: 'ips@ece.cmu.edu'
> Subject: iSCSI: draft 7: Abort Task and RefCmdSN
> 
> 
> The Task Management [function] Command PDU includes two fields
> currently only used by the ABORT TASK function:
> 
> 2.5.2 Referenced Task Tag  
>   Initiator Task Tag of the task to be aborted - for abort task 
>  
> 2.5.3 RefCmdSN [Referenced command sequence number]
>   For abort-task the task CmdSN to enable task removal. If 
> RefCmdSN is 
>   is lower that ExpCmdSN or higher than MaxCmdSN the target 
> will ignore 
>   RefCmdSN.
> 
> Both fields identify the task to be aborted.  The Referenced Task
> Tag field sits at the SCSI level and matches the SAM-2 function
> call description (SAM-2 revision 18):
> 6.2 ABORT TASK
>   Function call:
>     Service Response = ABORT TASK (IN (I_T_L_Q Nexus) )
> 
> The RefCmdSN field sits at the iSCSI level.
> 
> I suggest removing one of these fields.  Having two ways to
> specify the same thing just raises the question of what to do
> when the values don't agree.  If that happens, should the 
> target:
> send back a Reject PDU
> abort both tasks
> abort the task indicated by the Referenced Task Tag
> abort the task indicated by the RefCmdSN
> abort one of the tasks but also report an error
> do any of the above
> 
> Since task management functions in general may rely on the
> SCSI tag (although Abort Task is the only current user of it), 
> I suggest keeping that flag and dropping the iSCSI field.
> 
> --
> Robert.Elliott@compaq.com
> Compaq Computer Server Storage
>