SSC-3: Discussion related to Letter Ballot SYM-019-a
Kevin D Butt
kdbutt at us.ibm.com
Fri Jun 20 16:42:30 PDT 2008
Formatted message: <A HREF="r0806206_f.htm">HTML-formatted message</A>
Thanks Paul. I did not intend to limit the use case to the one I
mentioned. It is intended only as on example of one use case. There
certainly are more as you have pointed out.
Thanks,
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 us.ibm.com
http://www-03.ibm.com/servers/storage/
"Paul Suhler" <Paul.Suhler at Quantum.Com>
Sent by: owner-t10 at t10.org
06/20/2008 03:38 PM
To
<t10 at t10.org>
cc
Subject
RE: SSC-3: Discussion related to Letter Ballot SYM-019-a
I believe that there was another use case in which old tapes were copied
onto newer tapes to avoid wear becoming so bad that error rates would go
up too much. Keyless copy was seen as a way of improving the security of
this.
Thanks,
Paul
___________________________________
Paul A. Suhler | Firmware Engineer | Quantum Corporation | Office:
949.856.7748 | paul.suhler at quantum.com
___________________________________
Disregard the Quantum Corporation confidentiality notice below. The
information contained in this transmission is not confidential. Permission
is hereby explicitly granted to disclose, copy, and further distribute to
any individual(s) or organization(s), without restriction.
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Kevin D
Butt
Sent: Friday, June 20, 2008 11:14 AM
To: Roger Cummings
Cc: t10 at t10.org
Subject: RE: SSC-3: Discussion related to Letter Ballot SYM-019-a
Roger,
The group forced me to create the KCSLU and KCDLU terms in order to
describe the feature. In describing what one device is doing, I could
only talk about RAW because to read you need to be in RAW mode and for the
other when writing I could only talk about EXTERNAL because you need to be
in EXTERNAL to write. So I had to narrow the discussion depending on
whether I was talking about reading or writing. The keyless copy section
is intended to describe how to use the RAW and EXTERNAL modes. I
personally don't care what terms are used. Let me describe the intent
then we can understand what needs to be described. Hopefully this will
help us describe it clearly.
The intent is that a system can use the keyless copy capability to copy
data from one tape to another without requiring an encryption/decryption
key. The use case would be a data recovery lab. The lab are the experts
on getting the data off the tape but the user doesn't want to expose the
data. Hence the need to copy the data without having the decryption key.
I envision that if a device supports RAW it will also support EXTERNAL. I
really don't see a use case where support for one but not the other makes
sense. I would have no problem with stating that if RAW is supported
EXTERNAL shall be supported and vice-versa.
Thanks,
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 us.ibm.com
http://www-03.ibm.com/servers/storage/
"Roger Cummings" <roger_cummings at symantec.com>
06/20/2008 08:04 AM
To
Kevin D Butt/Tucson/IBM at IBMUS
cc
<t10 at t10.org>
Subject
RE: SSC-3: Discussion related to Letter Ballot SYM-019-a
Kevin,
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.
Regards,
Roger
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 t10.org [mailto:owner-t10 at t10.org] On Behalf Of Kevin D
Butt
Sent: Thursday, June 19, 2008 3:32 PM
To: t10 at t10.org
Subject: SSC-3: Discussion related to Letter Ballot SYM-019-a
SYM-019-a:
The 4.2.21.5 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 supported.
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.
Comments?
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 us.ibm.com
http://www-03.ibm.com/servers/storage/
The information contained in this transmission may be confidential. Any
disclosure, copying, or further distribution of confidential information
is not permitted unless such privilege is explicitly granted in writing by
Quantum Corporation. Furthermore, Quantum Corporation is not responsible
for the proper and complete transmission of the substance of this
communication or for any delay in its receipt.
More information about the T10
mailing list