SAT TEST UNIT READY command translation

Sheffield, Robert L robert.l.sheffield at intel.com
Fri Aug 12 08:22:19 PDT 2005


* From the T10 Reflector (t10 at t10.org), posted by:
* "Sheffield, Robert L" <robert.l.sheffield at intel.com>
*
There is a proposal in-process to redefine the Test Unit Ready
translation in SAT:
ftp://ftp.t10.org/t10/document.05/05-226r2.pdf

See the SAT WG agenda: http://www.t10.org/ftp/t10/sat-agnd.htm 

In this proposal - if the device is in standby the SATL issues the
command anyway. If it completes without error - GOOD status is returned.

Regarding Pat's comment: SAT defines no means to set the ATA password,
and no means to put the drive in SLEEP mode (except via the ATA
PASSTHROUGH command), and so if an application chooses to use
vendor-specific methods to set the password or put the drive into SLEEP
mode, it will require vendor-specific methods to deal with commands
issued when the drive is in SLEEP mode or is locked-out with a password.
The Test Unit Ready definition in 05-226 doesn't address this.

Best reagrds,
Bob Sheffield

-----Original Message-----
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Douglas
Gilbert
Sent: Thursday, August 11, 2005 3:31 AM
To: t10 at t10.org
Cc: jgarzik at pobox.com
Subject: SAT TEST UNIT READY command translation

* From the T10 Reflector (t10 at t10.org), posted by:
* Douglas Gilbert <dougg at torque.net>
*
SAT revision 05, section 8.12.2 [Miscellaneous notes
(on the TEST UNIT READY command)] states:

"a) The TEST UNIT READY command is mapped to the Check
Power Mode ATA command. If the drive is in standby
power mode, then it is assumed that the drive is
incapable of accepting media access commands without
any intervention, so a CHECK CONDITION is returned with
the sense key set to NOT READY and the additional sense
code set to LOGICAL UNIT NOT READY, INITIALIZING COMMAND
REQUIRED."

However a (s)ATA disk in standby power mode will transition
to active power mode automatically when a media access
command is received (albeit with a delay while the disk
spins up). A SCSI disk reacts the same way when it is
in standby mode. That additional sense code above is
appropriate when a SCSI disk is in stopped power state
(a state not defined for ATA disks). SAT translates
a START STOP UNIT (start=0) SCSI command to the Standby
ATA command (while the same SCSI command would put a
SCSI disk into stopped power state).
So is 8.12.2 miscellaneous note a) correct?

Alternatively SAT could define its REQUEST SENSE to yield
power condition information (as per SPC-3 rev 23).

Doug Gilbert


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