SPL question - START STOP Unit command in the Active_Wait state

Elliott, Robert (Server Storage) Elliott at hp.com
Fri Sep 18 15:25:46 PDT 2009


* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert (Server Storage)" <Elliott at hp.com>
*
The basic rule is in SBC-3 (sbc3r20 section5.20 page 108):
"If the immediate (IMMED) bit is set to zero, then the device server shall
return status after the operation is completed. If the IMMED bit set to one,
then the device server shall return status as soon as the CDB has been
validated."
With IMMED=0, the expectation is that the device server will be ready for
media access commands when GOOD status is returned (i.e., "the operation is
completed"; i.e., the SSU_PC1:Active state has been reached as requested). 
SAS's spinup controls are not intended to break that promise.
---
Rob Elliott, HP Industry Standard Server Storage
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of
Bill.Martin at emulex.com
Sent: Thursday, September 17, 2009 12:46 PM
To: t10 at t10.org
Subject: SPL question - START STOP Unit command in the Active_Wait state
In SPL, there is a lack of direction in the Active_Wait state related to the
START STOP UNIT command with START_VALID and the START bit set or ACTIVE.  I
have discussed this with a few people, and have gotten a few different
answers.  The issue is that the Active_Wait state discusses what to do with
any other version of the START STOP UNIT command, and if you enter the
Active_Wait state from the standby state, stopped state, or Idle_Wait state
because of a START STOP UNIT command with the POWER CONDITION field set to
START_VALID and the START bit set or with the POWER CONDITION field set to
ACTIVE, then the device server shall not complete the command until this
state machine reaches the SA_PC_1:Active state.  There is no indication of
what should be done with the START STOP UNIT command with these two
conditions if it is received while in the Active_Wait state.  This situation
can arise if the Active_Wait is entered after power on.
I am looking for collective wisdom on what the right answer is.  May the
device server immediately respond with GOOD status without exiting this
state?  Is there somewhere else in the specification that requires that the
device server shall be in the Active state before responding with GOOD
Status?  I have not been able to find the second of these conditions.
Bill Martin
Emulex
Office of Technology
Industry Standards
916 772-3658
916 765-6875 (Cell)
bill.martin at emulex.com
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