TASK SET FULL Definition(s) in FC-TAPE and SAM-2

JoeBre at Exabyte.COM JoeBre at Exabyte.COM
Wed Mar 17 10:18:03 PST 1999


* From the T10 Reflector (t10 at symbios.com), posted by:
* JoeBre at Exabyte.COM
*
Comment below....

> -----Original Message-----
> From: Bob Snively [mailto:Bob.Snively at ebay.sun.com]
> Sent: Wednesday, March 17, 1999 9:40 AM
> To: dap at nsg0.network.com; t10 at symbios.com; fc at nsg0.network.com
> Subject: Re: TASK SET FULL Definition(s) in FC-TAPE and SAM-2
> 
> 
> 
> Realistically, after placing my answers in the section below, 
> I believe
> that tagged queueing must be supported by FC-TAPE compliant 
> initiators,
> since only such initiators will do anything intelligent with 
> QUEUE FULL (TASK SET FULL).  Typically, their action is to retry
> infrequently and in addition to retry whenever a task is 
> completed from
> that logical unit.
> 
> Then the "cleaner" TASK SET FULL behavior can replace the present
> proper SCSI behavior of "vendor specific" or "OVERLAPPED 
> COMMANDS ATTEMPTED."
> 
> > b) the lun does not support tagged tasks, is processing a command
> > received from one Initiator (has no reservation active), 
> does not have
> > enough resources to receive another command and enter it into the
> > Task Set,  and receives another command from a different Initiator.
> > 
> > I would expect a TASK SET FULL.
> 
> There is a CHECK CONDITION ASC/ASCQ assigned for this behavior:
> 
> 	ASC/ASCQ 48/00  OVERLAPPED COMMANDS ATTEMPTED
> 	
> The check condition is provided by either command and the other is
> automatically aborted.

<Breher>
I don't understand why this is necessarily an OVERLAPPED COMMAND. I believe
that it is possible for a lun to run out of resources, other than the
Application Client trying to reuse a particular task address before it has
been retired.

It seems to me that the OVERLAPPED COMMANDS ATTEMPTED sense is an indication
of an extreme initiator fault, rather than the target running out of some
(unspecified) resource.
</Breher>
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