Interpretation of Logical unit Reset behavior

Elliott, Robert (Server Storage) Elliott at hp.com
Mon Oct 21 17:37:40 PDT 2002


* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert (Server Storage)" <Elliott at hp.com>
*
That's what these sentences are trying to allow.

(spc2r24)
5.9.6 Hard reset:
"Each SCSI transport protocol standard that defines reset events shall
specify the SCSI target port's action in response to reset events."

6.7 TARGET RESET:
NOTE 12 - ... SCSI transport protocols may require additional actions
beyond those specified here.

SPI-5 defines its actions with:
(spi5r03)
4.12.3 When to negotiation
A port shall set its negotiation required flags to true for all other
ports after a reset event (see 12.5).
...
After a reset event a port shall set its transfer agreements for all
other ports to the default transfer agreement (see table 4).

12.5.4 Target reset event
When a SCSI device successfully receives a TARGET RESET message, it
shall cause a reset event. 


--
Rob Elliott, elliott at hp.com
Industry Standard Server Storage Advanced Technology
Hewlett-Packard



> -----Original Message-----
> From: Binford, Charles [mailto:CBinford at pirus.com] 
> Sent: Monday, October 21, 2002 6:11 PM
> To: t10 at t10.org
> Subject: RE: Interpretation of Logical unit Reset behavior
> 
> 
> * From the T10 Reflector (t10 at t10.org), posted by:
> * "Binford, Charles" <CBinford at Pirus.com>
> *
> Robert,  while I agree with your conclusion, I think it is 
> hard to justify your last statement, "TARGET RESET does the 
> target port resetting." from any words I can find in SAM-2.  
> Everywhere I looked Target Reset was merely a LUN reset to 
> each LU.  My reading says the result of a host sending a LUN 
> Reset to each LU, and a host sending a Target Reset would be 
> the same.  I don't see anything to suggest Target Reset 
> should have special handling of the port parameters.  What did I miss?
> 
> Charles Binford
> Pirus Networks
> 316.315.0382 x222
> 
> 
> -----Original Message-----
> From: Elliott, Robert (Server Storage) [mailto:Elliott at hp.com]
> Sent: Friday, October 18, 2002 6:08 PM
> To: t10 at t10.org
> Subject: RE: Interpretation of Logical unit Reset behavior
> 
> 
> * From the T10 Reflector (t10 at t10.org), posted by:
> * "Elliott, Robert (Server Storage)" <Elliott at hp.com>
> *
> This question was raised in March 2001 during the negotiation 
> rewrite, and 
> 	01-128r2 (1 May 2001) SPI-4 reset cleanup 
> added the rule that LOGICAL UNIT RESET shall not affect the 
> negotiation.
> 
> 
> Negotiated settings are a property of the target port shared 
> by all the logical units. In a target with multiple logical 
> units, reset of one of the logical units shouldn't affect the 
> others' ability to communicate.
> 
> SAM-2 just says the logical unit should be returned to a 
> power-on-like state, not the target port.  TARGET RESET does 
> the target port resetting.
> 
> --
> Rob Elliott, elliott at hp.com
> Industry Standard Server Storage Advanced Technology Hewlett-Packard
> 
> 
> 
> > -----Original Message-----
> > From: gerry.houlder at seagate.com [mailto:gerry.houlder at seagate.com]
> > Sent: Friday, October 18, 2002 4:26 PM
> > To: t10 at t10.org
> > Subject: Interpretation of Logical unit Reset behavior
> > 
> > 
> > * From the T10 Reflector (t10 at t10.org), posted by:
> > * gerry.houlder at seagate.com
> > *
> > A contradiction has been pointed out for the description of
> > the Logical Unit Reset behavior. In particular, note the 
> > requirements I have marked with double brackets << >>.
> > 
> > From SPI - 4 or 5:
> > 
> >    16.5.6 LOGICAL UNIT RESET
> >    The LOGICAL UNIT RESET message is defined in the SCSI 
> Architecture
> >    Model-2 standard.
> >    Receipt of the LOGICAL UNIT RESET message after an I_T_L
> > nexus has been
> >    established is a logical
> >    unit reset event as defined in the SCSI Architecture 
> > Model-2 standard.
> >    In addition to the requirements in the SCSI Architecture Model-2
> >    standard the SCSI target port shall go to
> >    the BUS FREE phase following the successful receipt of the 
> > LOGICAL UNIT
> >    RESET message.
> > 
> >    <<A logical unit reset has no effect on the transfer agreement.>>
> > 
> > From SCSI Architecture Model-2 standard
> > 
> >    5.9.7 Logical unit reset
> >    A logical unit reset is:
> >    a) The action in response to a LOGICAL UNIT RESET task management
> >    request (see 6.6) or some other
> >    logical unit reset event; or
> >    b) One of the actions in response to a TARGET RESET task 
> management
> >    function (see 6.7) or a hard reset
> >    (see 5.9.6).
> >    The definition of logical unit reset events is dependent
> > on the SCSI
> >    transport protocol.
> >    To process a logical unit reset the logical unit shall:
> >    a) Abort all tasks as described in 5.7;
> >    b) Clear a CA (see 5.9.1.6) or ACA (see 5.9.1.7) 
> > condition, if one is
> >    present;
> >    c) Release all reservations established using the reserve/release
> >    management method (persistent reserva-tions
> >    shall not be affected);
> >    <<d) Return the logical unit's operating mode to the 
> > appropriate initial
> >    conditions, similar to those conditions that
> >    would be found following device power-on.>> The MODE 
> > SELECT parameters
> >    (see SPC-2) shall be restored
> >    to their last saved values if saved values have been 
> > established. MODE
> >    SELECT parameters for which no
> >    saved values have been established shall be returned to 
> > their default
> >    values;
> >    e) Set an unit attention condition (see 5.9.5); and
> >    f) Initiate a logical unit reset for all dependent logical 
> > units (see
> >    4.13).
> >    In addition to the above, the logical unit shall perform 
> > any additional
> >    functions required by the applicable standards.
> > 
> > The wording from SPI says "no effect on transfer agreement",
> > meaning the target has to remember the transfer agreement 
> > even though everything else is being reset. The SAM wording 
> > says "similar to power on", which certainly includes 
> > resetting the transfer agreement. These conditions certainly 
> > conflict with each other. How do we resolve the conflicting wording?
> > 
> > The single LUN targets I am familiar with reset all the same
> > things (including the transfer agreement) for both of these 
> > functions. Are these devices in violation of the standard?
> > 
> > *
> > * For T10 Reflector information, send a message with
> > * 'info t10' (no quotes) in the message body to majordomo at t10.org
> > 
> *
> * For T10 Reflector information, send a message with
> * 'info t10' (no quotes) in the message body to majordomo at t10.org
> *
> * For T10 Reflector information, send a message with
> * 'info t10' (no quotes) in the message body to majordomo at t10.org
> 
*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org




More information about the T10 mailing list