task states?

Mallikarjun C. cbm at rose.hp.com
Mon Feb 11 11:52:26 PST 2002


* From the T10 Reflector (t10 at t10.org), posted by:
* "Mallikarjun C." <cbm at rose.hp.com>
*
Rob,

Thanks for the response, please allow me to copy it to the list.


"Elliott, Robert" wrote:
> 
> I think it's correct.
> 
> The task is made of multiple commands.  The task itself is what goes
> through those states, not each individual command.  If you get a CA all
> the linked commands are blocked as a set.

Okay, that's the other possibility I suspected and which SAM-2's 
current language upon closer reading seems to confirm, but here's
my reasoning for thinking that each of the commands goes through
the same state transitions.

- I assumed a device server may need to address resource constraints 
  before a task is transitioned out of the Dormant state.  If this
  is a reasonable interpretation of SAM-2's language, then the same
  constraints would need to be faced and addressed for each of the
  commands in a task.  It sounds like SAM-2 would rather suggest the
  constraints be addressed in the Enabled state for linked commands...
 
- I reasoned that if a Reservation on an LU is obtained by one initiator 
  when a second initiator is half way through its task with linked
commands, 
  the next (linked) command from the second initiator should get a
RESERVATION 
  CONFLICT - thus implying that each command goes through the
transitions.
  If it were the task going through the transitions, (since it's already
  transitioned to the Enabled state,) none of the following linked
commands 
  would see a reservation conflict even though the device server by then
  is reserved for exclusive use by the first initiator.  It seems to be
  that the latter behavior is currently intended....

Thanks.
-- 
Mallikarjun 


Mallikarjun Chadalapaka
Networked Storage Architecture
Network Storage Solutions Organization
MS 5668	Hewlett-Packard, Roseville.
cbm at rose.hp.com


> 
> > -----Original Message-----
> > From: Mallikarjun C. [mailto:cbm at rose.hp.com]
> > Sent: Sunday, February 10, 2002 11:36 PM
> > To: t10 at t10.org
> > Subject: task states?
> >
> >
> > * From the T10 Reflector (t10 at t10.org), posted by:
> > * "Mallikarjun C." <cbm at rose.hp.com>
> > *
> > All,
> >
> > SAM-2 (clause 7.4) describes the states a task goes through
> > on a target.
> >
> > In the case of linked commands, as far as I can tell, each of the
> > commands goes through the same transitions.  So, it appears to
> > me that the states be called "command states".
> >
> > Apologies if this is discussed earlier, a pointer would be
> > appreciated.
> > If not, providing the reason behind the current terminology
> > would help
> > my understanding.
> >
> > Thanks!
> > --
> > Mallikarjun
> >
> > Mallikarjun Chadalapaka
> > Networked Storage Architecture
> > Network Storage Solutions Organization
> > Hewlett-Packard MS 5668
> > Roseville CA 95747
> >
> > *
> > * For T10 Reflector information, send a message with
> > * 'info t10' (no quotes) in the message body to majordomo at t10.org
> >
*
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