Comments on 05-177r0 "write same"

Sheffield, Robert L robert.l.sheffield at intel.com
Wed May 4 14:05:40 PDT 2005


* From the T10 Reflector (t10 at t10.org), posted by:
* "Sheffield, Robert L" <robert.l.sheffield at intel.com>
*
Jim,

The SAT WG agreed that whether the SATL issues an SCD LBA Segment Access
command is contingent on whether the device reports in IDENTIFY DEVICE
that it supports SCD LBA Segment Access. The SAT standard cannot base
any standard requirements on vendor-specific or out-of-band controls
that might modify what a device supports or not, so it is not
appropriate to specify SATL behavior with respect to whether or not SCT
LBA Segment Access or SCD (in general) is "enabled". Any coordination
between a SATL with regards to vendor-specific enable/disable of these
features is, of course, vendor-specific, and not documented in the
standard.

Regards,
Bob

-----Original Message-----
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of
James.C.Hatfield at seagate.com
Sent: Wednesday, May 04, 2005 12:47 PM
To: curtis.stevens at wdc.com
Cc: t10 at t10.org
Subject: RE: Comments on 05-177r0 "write same"

* From the T10 Reflector (t10 at t10.org), posted by:
* James.C.Hatfield at seagate.com
*
You are correct in stating that there is no documented standard
way to 'enable or disable' SCT LBA Segment Access, but there <is> a
documented way for the device to separately report that
     a) it supports (or not) SCT (in general)     <and>
     b) is supports (or not) SCT LBA Segment Access

It is vendor unique whether or not there is a way to change the settings
of these bits.

Please refer to the SCT Technical report (1701DT rev 5, page 5)
      IDENTIFY DEVICE, word 206
      bit 0 = SCT Feature set supported (includes SCT status)
      bit 2 = LBA Segment Access (AC2) supported

I request that the SAT document needs to address what to do if bit 0 is
set
to one
and bit 2 is cleared to zero.

Thank You !!!
-----------------------------------------------------------------
Jim Hatfield
Seagate Technology LLC
   e-mail:  James.C.Hatfield at seagate.com
   s-mail:  389 Disc Drive;  Longmont, CO 80503 USA
   voice:  720-684-2120
   fax....:  720-684-2711

========================================================================
======
(from Curtis Stevens' notes of the discussion at the SAT meeting May 3
2005)

1. OPCODE - Is there a preferred hierarchy of choices for
implementation?
      If a device does not support SCT, is there a preference for the
other
2
      choices?

      Committee Respose:
      a. Wording was changed to reference SCT LBA Segment Access.
      There is no enable or disable for this capability.

3. Please clarify the meaning of "device implements SCT".  See 1a above.

4. What if the ATA device (target) 'supports' SCT, but does not have it
(or
the LBA Segment Access subcommand) enabled?

Committee Response:
      There is enable/disable for SMART, but there is no enable or
disable
for SCT.

*
* 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