SSC-3: Discussion related to Letter Ballot SYM-019-a

Roger Cummings roger_cummings at
Fri Jun 20 08:04:38 PDT 2008

Formatted message: <A HREF="r0806202_f.htm">HTML-formatted message</A>

I'm not sure that I can accept your simplification that this collapses
to which settings of "ENCRYPTION MODE" and "DECRYPTION MODE" fields are
supported. The issue I'm having relates to the second paragraph on page
55 (PDF page 74) of SSC-3 Rev 4a, which seems to imply that for some
encryption algorithms it's necessary for the KCSLU to support both
EXTERNAL & RAW modes, but for others RAW support is sufficient. Is the
converse of this true i.e. some LUs that support RAW mode will NOT be
able to act as KCSLUs?
I do agree that this would be a useful simplification if we can resolve
the above point, which I freely admit may be a misunderstanding on my
point. And being able to read the capability of an LU wrt encryption
modes in advance would definitely be a useful thing for our apps. But if
we can make that simplification then I'd recommend that we delete the
terms KCSLU & KCDLU in their entirety as all they mean is "an LU that
supports RAW mode" and "an LU that supports EXTERNAL mode" respectively.
P.S. And I haven't forgotten that I have an AI related to SYM-019-b, and
I hope to have something on that subject ready for Anchorage.
	From: owner-t10 at [mailto:owner-t10 at] On Behalf Of
Kevin D Butt
	Sent: Thursday, June 19, 2008 3:32 PM
	To: t10 at
	Subject: SSC-3: Discussion related to Letter Ballot SYM-019-a
	The Keyless copy section should identify How an
application client determines that a Logical Unit has the capability to
act as a KCSLU or a KCDLU 
	There is no bit anywhere that indicates the support for acting
as a KCSLU or KCDLU.  In reality, it is if the LU supports the EXTERNAL
encryption mode or the RAW decryption mode.  So the request here should
be reworded to say how does an application client determine which
settings of "ENCRYPTION MODE" and "DECRYPTION MODE" fields are
	Looking at the section describing each of these fields, there is
no text describing a CC returned for RAW or EXTERNAL if they are not
supported.  The standard is silent.  This is also the case for DISABLE.
Obviously the standard does not explicitly indicate anywhere that these
modes are optional. 
	What should we do? 
	Option 1: Add text under the description of these fields stating
that if EXTERNAL or RAW mode is selected and it is not supported then
CC.  This would change the standard to explicitly state that these
options are optional. 
	Option 2: Add text somewhere to mandate support for these modes.
I suspect this option is not desired. 
	I think that we must do either option 1 or option 2.  The
standard needs to be clear if these are optional or not. 
	If we go done the path that these are explicitly stated as
optional, then this letter ballot comment leads to the question, "How do
we report support for different values in these two fields?"  This is
not just a question of Keyless copy but also of MIXED decryption mode.
There is an implication that ENCRYPT and DECRYPT are supported as well
as DISABLE.  I am not sure that is correct.  There could be a device
that only supportes one or the other or some combinations. 
	Kevin D. Butt
	SCSI & Fibre Channel Architect, Tape Firmware
	MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
	Tel: 520-799-2869 / 520-799-5280
	Fax: 520-799-2723 (T/L:321)
	Email address: kdbutt at 

More information about the T10 mailing list