Format Unit SI bit

Mark Evans Mark.Evans at wdc.com
Tue Jun 7 10:39:25 PDT 2011


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1106072_f.htm">HTML-formatted message</a>

Hi George,
There are just too many "shalls" in the definition for the bit set to one
for this to be as open-ended as you describe:
a)	 ...the device server shall attempt to write the initialization
pattern to all areas of the medium including those that may have been
reassigned (i.e., are in a defect list)...;
b)	...An SI bit set to one shall take precedence over any other FORMAT
UNIT CDB field...; and
c)	 ...the initialization pattern shall be written using a security
erasure write technique....
Though I'll admit that item (c) is certainly vendor specific, I don't see
where there is even a hint that the target device will end up being "totally
inoperable".
Gerry, I can see now that all of the information in the command and
parameter data could be used if the logical unit was to perform the security
initialize function and then finish with a normal format operation.  We
don't say this anyplace, but this condition could fall into George's list of
vendor specific behavior.
All of that written, I still think we need to clarify item (b).  I now think
that what was meant is:  "...the security initialize function shall take
precedence over any other function specified by the FORMAT UNIT command."
To me this means that you have to do the security initialize stuff first,
then whatever else you do is vendor specific.
Please feel free to call or send an email to me with any comments or
questions that you have about this stuff. 
Regards, 
Mark Evans
Western Digital Corporation
5863 Rue Ferrari
San Jose, CA 95138
Email: mark.evans at wdc.com
________________________________
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Penokie,
George
Sent: Tuesday, June 07, 2011 9:02 AM
To: Gerry Houlder; T10 Reflector
Cc: Truong Nguyen - SISA
Subject: RE: Format Unit SI bit
You are both right and wrong.
What happen when the SI bit is set depends on the customers specification.
Is some cases the intent may that the device be totally inoperable (think
the helicopter and all electronics need to be destroyed). In less radical
conditions the drive may come back usable with data scrubbed off. 
At the time this was put in there was no agreement by the committee as to
how scrubbed the data had to be, again that was intended to be left up to
the customers specification.
Bye for now, 
George Penokie 
LSI Corporation 
3033 41st St. NW 
Suite 100 
Rochester, MN 55901 
507-328-9017 
george.penokie at lsi.com 
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Gerry
Houlder
Sent: Tuesday, June 07, 2011 10:18 AM
To: T10 Reflector
Cc: Truong Nguyen - SISA
Subject: Re: Format Unit SI bit
I think Mark's interpretation is too broad. The SI bit is intended to
trigger a vendor specific security initialize feature. Things the device has
to do to implement this take precedence over other bits that might specify
conflicting demands. However things that specify the required final format
(e.g., logical block size, FMTPINFO) and whether existing defect lists are
included or not (e.g., FMTDATA, CMPLST, DEFECT LIST FORMAT, defect list
length) should still be obeyed. If an initialization pattern is specified,
that should be the pattern left on the media after the security initialize
is complete. The SI bit probably affects how defective areas (i.e., areas
excluded from the user data area) are treated, but should not cause the
device to ignore instructions about which areas are to be handled as
defective areas.
On Fri, Jun 3, 2011 at 10:56 AM, Mark Evans <Mark.Evans at wdc.com> wrote:
Hi Truong,
The SI bit was added into the INITIALIZATION PATTERN DESCRIPTOR for the
FORMAT UNIT command in SBCr-05 based on proposal 96-186R1.  As you wrote the
definition of the bit was modified slightly in SBC-r06 as the result of
discussion at the SCSI working group meetings in October of 1996.  The
definition of the SI bit has not been changed since that time.
What I think we really intended the new wording to mean is, "If the SI bit
its set to one, then the device server shall ignore:
a)	 the FMTPINFO field;
b)	the FMTDATA bit;
c)	 the CMPLST bit;
d)	the DEFECT LIST FORMAT field;
e)	 all of the bits and fields in the parameter list header, except the
IMMED bit; and
f)	  any defect list data.
Others may correct me if I'm wrong.  You know who you are, and I'm sure you
will - ha!
Please feel free to call or send an email to me with any comments or
questions that you have about this stuff. 
Regards, 
Mark Evans
Western Digital Corporation
5863 Rue Ferrari
San Jose, CA 95138
Email: mark.evans at wdc.com
________________________________
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Truong
Nguyen - SISA
Sent: Thursday, June 02, 2011 5:54 PM
To: t10 at t10.org
Subject: Format Unit SI bit
In SBC3r27, in the Format Unit initialization pattern descriptor subclause
5.3.2.3, there is a statement regarding the SI bit precedence:
"An SI bit set to one shall take precedence over any other FORMAT UNIT CDB
field."
What is this statement supposed to mean specifically?
It seems as though the statement was added some time ago in SBCr6:
ftp://ftp.t10.org/t10/t10r/1996/r9610141.htm
"Clarified SI by adding the statement An SI bit set to one shall take
precedence over any other FORMAT UNIT field."
I could not find any proposals associated with the modification.
Thanks,
Truong Nguyen
Samsung Information Systems America



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