Format Unit SI bit

Jon Haswell - SISA jon.haswell at sisa.samsung.com
Tue Jun 7 11:27:45 PDT 2011


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1106073_f.htm">HTML-formatted message</a>

I would agree with your last comment, re needing to clarify (b). Wording
such as 'take precedence over'	is very ambiguous. To me 'taking
precedence over' implies it overrides other settings if they conflict,
but any conflict is vendor unique/unspecified so nobody can rely on what
will or will not be overridden. 
We are currently implementing it so we do the security initialize first
and then we implement everything else, we actually have no conflicts so
we implement every other function/feature requested after the initialize
is completed.
I would prefer to see some statement that is definitive such as, 'When
the SI bit is specified all other options are ignore' if that is really
what is intended. Or if not let's get specific as we do in other
commands/mode pages where we define what bits are honored/ignored where
we have multiple bits that conflict/interact.
Thanks
Jon Haswell
SSD Development
Office	408 544 5869
Cell	 408 472 2495
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Mark
Evans
Sent: Tuesday, June 07, 2011 10:39 AM
To: Penokie, George; Gerry Houlder; T10 Reflector
Cc: Truong Nguyen - SISA
Subject: RE: Format Unit SI bit
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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