[T10] Revisiting the RMB (Removable Medium) bit definition

Kevin D Butt kdbutt at us.ibm.com
Thu Jul 30 12:08:28 PDT 2020


Ralph, 

This looks good to me. I am still trying to wrap my head around "break the 
I_T nexus" since this is the first use in SPC or SAM. However, I think the 
standard English meaning works well here.

Kevin D. Butt
SCSI Architect, Tape Firmware, Data Retention Infrastructure
T10 Standards
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com

=========== Interesting Links ===========
[ IBM Tape Storage ]  https://www.ibm.com/it-infrastructure/storage/tape
[ SSIC - HBA/OS/Switch/Product interoperation ] 
https://www-304.ibm.com/systems/support/storage/ssic/interoperability.wss
[ LTO & 3592 ISV Support Matrix ] 
www.ibm.com/systems/resources/lto_isv_matrix.pdf
[ LTO SCSI Reference ] 
http://www-01.ibm.com/support/docview.wss?uid=ssg1S7003556
[ 3592 SCSI Reference ] 
http://www-01.ibm.com/support/docview.wss?uid=ssg1S7003248
===================================



From:   Ralph Weber <Ralph.Weber at wdc.com>
To:     "t10 at t10.org" <t10 at t10.org>
Date:   07/30/2020 11:59
Subject:        [EXTERNAL] Re: [T10] Revisiting the RMB (Removable Medium) 
bit definition
Sent by:        t10-bounces at t10.org



Kevin,
 
This doesn?t look too difficult to solve.
 
A removable medium (rmb) bit set to zero indicates that the medium is not 
removable or is able to be removed only if that removal is accompanied by 
the breaking of the I_T nexus connection between the application client to 
the device server.  A rmb bit set to one indicates that the medium is 
removable able to be removed without affecting the I_T nexus between the 
application client and the device server.
 
All the best, .Ralph
 
 
From: Kevin D Butt <kdbutt at us.ibm.com> 
Sent: Thursday, July 30, 2020 10:42 AM
To: Ralph Weber <Ralph.Weber at wdc.com>
Cc: t10 at t10.org
Subject: RE: [T10] Revisiting the RMB (Removable Medium) bit definition
 
CAUTION: This email originated from outside of Western Digital. Do not 
click on links or open attachments unless you recognize the sender and 
know that the content is safe.
 
Ralph,

That does solve the mentioned problems. It does, however, cause a nuanced 
change in meaning from "not removable" to "able to be removed only if". 
The original definition says if the RMB bit is zero the medium is not 
removable whereas the new definition says the medium can actually be 
removed, but only if the device server goes away with it. While that does 
seem to be the intent of this effort, I have to wonder if it is not 
actually changing the meaning.

My concern is rooted in making sure we don't break something else. From 
tape devices, I do not see the proposed definition to be an issue. 
However, I don't have much a view into the application client side of 
things outside the tape world. Do application clients expect that the 
medium is never removed is the RMB bit is set to zero? If the I_T nexus is 
broken, do they search other I_T nexuses to try and find the medium?

Thanks,

Kevin D. Butt
SCSI Architect, Tape Firmware, Data Retention Infrastructure
T10 Standards
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com

=========== Interesting Links ===========
[ IBM Tape Storage ]  https://www.ibm.com/it-infrastructure/storage/tape
[ SSIC - HBA/OS/Switch/Product interoperation ] 
https://www-304.ibm.com/systems/support/storage/ssic/interoperability.wss
[ LTO & 3592 ISV Support Matrix ] 
www.ibm.com/systems/resources/lto_isv_matrix.pdf
[ LTO SCSI Reference ] 
http://www-01.ibm.com/support/docview.wss?uid=ssg1S7003556
[ 3592 SCSI Reference ] 
http://www-01.ibm.com/support/docview.wss?uid=ssg1S7003248
===================================



From:        Ralph Weber <Ralph.Weber at wdc.com>
To:        "t10 at t10.org" <t10 at t10.org>
Date:        07/30/2020 04:35
Subject:        [EXTERNAL] Re: [T10] Revisiting the RMB (Removable Medium) 
bit definition
Sent by:        t10-bounces at t10.org

 
Kevin,
Having slept on the problem, it?s become apparent that symmetry requires 
the addition of ?is not able to be? to the first sentence, a la?
A removable medium (rmb) bit set to zero indicates that the medium is not 
removableable to be removed only if that removal is accompanied by the 
breaking of the I_T nexus connection between the application client to the 
device server.  A rmb bit set to one indicates that the medium is 
removableable to be removed without affecting the I_T nexus between the 
application client and the device server.
 
All the best, .Ralph
 
From:John Geldman <John.Geldman at kioxia.com> 
Sent: Thursday, July 30, 2020 12:37 AM
To: Ralph Weber <Ralph.Weber at wdc.com>; t10 at t10.org
Subject: RE: [T10] Revisiting the RMB (Removable Medium) bit definition
 
CAUTION:This email originated from outside of Western Digital. Do not 
click on links or open attachments unless you recognize the sender and 
know that the content is safe.
 
Ralph, 
 
I seem to be missing something. 
 
>From my world view RMB was/is about removable media, not removable 
devices. We still want it to be. If we declare that rmb set to zero means 
not able to remove the media, then to remove the media, the device server 
has to be removed, i.e., disconnected. 
 
The statement that removal of a device breaks the connection to the host 
needs to be said? 
 
Isn?t the problem folks thinking RMB was/is about removable devices? 
 
John
 
From:t10-bounces at t10.org<t10-bounces at t10.org> On Behalf Of Ralph Weber
Sent: Wednesday, July 29, 2020 6:45 PM
To: t10 at t10.org
Subject: Re: [T10] Revisiting the RMB (Removable Medium) bit definition
 
IMHO The absence of any statement about the I_T nexus in the RMB=0 case 
severely limits the value of the change.
 
From:John Geldman <John.Geldman at kioxia.com> 
Sent: Wednesday, July 29, 2020 8:27 PM
To: Ralph Weber <Ralph.Weber at wdc.com>; t10 at t10.org
Subject: RE: [T10] Revisiting the RMB (Removable Medium) bit definition
 
CAUTION:This email originated from outside of Western Digital. Do not 
click on links or open attachments unless you recognize the sender and 
know that the content is safe.
 
The observations are all correct, but they do obfuscate. Does this work?
 
A removable medium (rmb) bit set to zero indicates that the medium is not 
removable able to be removed from the device server. A rmb bit set to one 
indicates that the medium is removableable to be removed from the device 
server. If the rmb bit is set to one and the medium is removed, then the 
I_T nexus between the application client and the device server, if any, is 
not affected.
 
John
 
From:t10-bounces at t10.org<t10-bounces at t10.org> On Behalf Of Ralph Weber
Sent: Wednesday, July 29, 2020 5:52 PM
To: t10 at t10.org
Subject: Re: [T10] Revisiting the RMB (Removable Medium) bit definition
 
I agree that the two sentence are not symmetrical, however? I cannot find 
a way to make them symmetrical that does not involve an excess of Rube 
Goldberg English that obfuscates more than it clarifies.
 
Please feel free to augment the suggestion made below with detailed text 
changes.
 
All the best, .Ralph
 
From:Kevin D Butt <kdbutt at us.ibm.com> 
Sent: Wednesday, July 29, 2020 3:42 PM
To: Ralph Weber <Ralph.Weber at wdc.com>
Cc: t10 at t10.org
Subject: RE: [T10] Revisiting the RMB (Removable Medium) bit definition
 
CAUTION:This email originated from outside of Western Digital. Do not 
click on links or open attachments unless you recognize the sender and 
know that the content is safe.
 
That is starting to look good to me, but I would suggest making it 
symmetrical.
A removable medium (rmb) bit set to zero indicates that the medium is not 
removable able to be removed without removing the I_T nexus that connects 
the application client to the device server.  A rmb bit set to one 
indicates that the medium is removableable to be removed without affecting 
the I_T nexus between the application client and the device server.


Kevin D. Butt
SCSI Architect, Tape Firmware, Data Retention Infrastructure
T10 Standards
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com

=========== Interesting Links ===========
[ IBM Tape Storage ]  https://www.ibm.com/it-infrastructure/storage/tape
[ SSIC - HBA/OS/Switch/Product interoperation ] 
https://www-304.ibm.com/systems/support/storage/ssic/interoperability.wss
[ LTO & 3592 ISV Support Matrix ] 
www.ibm.com/systems/resources/lto_isv_matrix.pdf
[ LTO SCSI Reference ] 
http://www-01.ibm.com/support/docview.wss?uid=ssg1S7003556
[ 3592 SCSI Reference ] 
http://www-01.ibm.com/support/docview.wss?uid=ssg1S7003248
===================================



From:        Ralph Weber <Ralph.Weber at wdc.com>
To:        "t10 at t10.org" <t10 at t10.org>
Date:        07/29/2020 13:20
Subject:        [EXTERNAL] Re: [T10] Revisiting the RMB (Removable Medium) 
bit definition
Sent by:        t10-bounces at t10.org

 
Or? how about something along the lines of:
A removable medium (rmb) bit set to zero indicates that the medium is not 
removable without removing the I_T nexus that connects the application 
client to the device server.  A rmb bit set to one indicates that the 
medium is removableable to be removed without affecting the I_T nexus 
between the application client and the device server.
 
 
From:Curtis Stevens <curtis.stevens at seagate.com> 
Sent: Wednesday, July 29, 2020 3:12 PM
To: Ballard, Curtis C (HPE Storage) <curtis.ballard at hpe.com>; Kevin D Butt 
<kdbutt at us.ibm.com>; Ralph Weber <Ralph.Weber at wdc.com>
Cc: t10 at t10.org
Subject: Re: [T10] Revisiting the RMB (Removable Medium) bit definition
 
CAUTION:This email originated from outside of Western Digital. Do not 
click on links or open attachments unless you recognize the sender and 
know that the content is safe.
 
I think part of the blatant wording that Ralph is proposing is that those 
making the requirements on the device side do not fully understand SCSI. 
This has been the case from day 1 and has not changed.  It is fairly easy 
to understand commands and what they do.  Understanding the architecture 
is a different story.
 
I think your suggested change could be integrated with Ralphs change...
 
 
---------------------------------------------
Curtis E. Stevens
Technologist
Seagate Technology
 
E-Mail: Curtis.Stevens at Seagate.com
Phone: 949-307-5050
 

From:Ballard, Curtis C (HPE Storage) <curtis.ballard at hpe.com>
Sent: Wednesday, July 29, 2020 12:49 PM
To: Curtis Stevens <curtis.stevens at seagate.com>; Kevin D Butt <
kdbutt at us.ibm.com>; Ralph Weber <Ralph.Weber at wdc.com>
Cc: t10 at t10.org<t10 at t10.org>
Subject: RE: [T10] Revisiting the RMB (Removable Medium) bit definition 
 
Why don?t we specify it in architectural terms.  Something along the lines 
of:
A removable medium (rmb) bit set to zero indicates that the medium is not 
removable from the device server. 
A rmb bit set to one indicates that the medium is removableable to be 
removed without removing the device server.
 
Curtis Ballard
Hewlett Packard Enterprise
HPE Storage R&D
Fort Collins, CO
(970) 898-3013
 
From:t10-bounces at t10.org[mailto:t10-bounces at t10.org] On Behalf Of Curtis 
Stevens
Sent: Wednesday, July 29, 2020 1:04 PM
To: Kevin D Butt <kdbutt at us.ibm.com>; Ralph Weber <Ralph.Weber at wdc.com>
Cc: t10 at t10.org
Subject: Re: [T10] Revisiting the RMB (Removable Medium) bit definition
 
I would turn the proposal around and say the RMB bit shall only be set to 
one if the device is able to report ... after is media is ejected.
 
 
---------------------------------------------
Curtis E. Stevens
Technologist
Seagate Technology
 
E-Mail: Curtis.Stevens at Seagate.com
Phone: 949-307-5050
 

From:t10-bounces at t10.org<t10-bounces at t10.org> on behalf of Kevin D Butt <
kdbutt at us.ibm.com>
Sent: Wednesday, July 29, 2020 8:48 AM
To: Ralph Weber <Ralph.Weber at wdc.com>
Cc: t10 at t10.org<t10 at t10.org>
Subject: Re: [T10] Revisiting the RMB (Removable Medium) bit definition
 
Ralph,

I applaud your goal, however, I am concerned about this definition. Take, 
for example, a tape library. It has removable media, yet it would not 
report one of these two additional sense codes. Even if all user 
cartridges were removed, the library would still be ready. It could do 
management type things including using diagnostic cartridges (not seen as 
medium to the application client) to test drives.

The RMBshould be set to zero, if the device server is not able to 
terminate a TEST UNIT READY command (6.48) with CHECK CONDITION status, 
with the sense key set to NOT READY and the additional sense code:
a)set to NOT READY, MEDIUM NOT PRESENT; or
b)having the ADDITIONALSENSECODEfield (see 4.4.2 and 4.4.3) set to 3Ah 
(e.g., MEDIUM NOT PRESENT - TRAY OPEN).

Thanks,

Kevin D. Butt
SCSI Architect, Tape Firmware, Data Retention Infrastructure
T10 Standards
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com

=========== Interesting Links ===========
[ IBM Tape Storage ]  https://www.ibm.com/it-infrastructure/storage/tape
[ SSIC - HBA/OS/Switch/Product interoperation ] 
https://www-304.ibm.com/systems/support/storage/ssic/interoperability.wss
[ LTO & 3592 ISV Support Matrix ] 
www.ibm.com/systems/resources/lto_isv_matrix.pdf
[ LTO SCSI Reference ] 
http://www-01.ibm.com/support/docview.wss?uid=ssg1S7003556
[ 3592 SCSI Reference ] 
http://www-01.ibm.com/support/docview.wss?uid=ssg1S7003248
===================================



From:        Ralph Weber <Ralph.Weber at wdc.com>
To:        "t10 at t10.org" <t10 at t10.org>
Date:        07/29/2020 06:49
Subject:        [EXTERNAL] Re: [T10] Revisiting the RMB (Removable Medium) 
bit definition
Sent by:        t10-bounces at t10.org

 

Proposal 20-082r0SPC-6: Removable Medium Bit Expectations has been posted 
to bring this discussion thread to the attention of CAP.

Resisting the ongoing calls to put as many words as possible into every 
standard, the proposal includes only one of the methods for defining a 
?real? removable medium device discussed in this thread. For the purposes 
discussed here, only one method is necessary to sufficiently define the 
standard.

All the best, .Ralph

From:t10-bounces at t10.org <t10-bounces at t10.org> On Behalf Of Michael 
Webster
Sent: Tuesday, July 21, 2020 7:57 PM
To: t10 at t10.org
Subject: Re: [T10] Revisiting the RMB (Removable Medium) bit definition

I would like to add one other tidbit:  A device reporting RMB=1 in 
addition to being capable of a state that reports MEDIUM NOT PRESENT, such 
a device should also properly support and execute an ejection operation of 
that media when sent a START/STOP UNIT command with Power_Condition=0, 
LoEj=1, & Start=0.

Mike Webster
Western Digital

From: <t10-bounces at t10.org> on behalf of Mike Webster <
Mike.Webster at wdc.com>
Date: Friday, July 17, 2020 at 10:30 AM
To: "t10 at t10.org" <t10 at t10.org>
Subject: Re: [T10] Revisiting the RMB (Removable Medium) bit definition

I would expect a USB memory stick to report RMB=0 and ejection causes the 
whole device to be removed from the operating system?s driver stack. 
Afterward, such an ejected device would require an unplug/re-plug for the 
device to respond to anything on USB.

Unless that USB memory stick included a slot for media (e.g. an SD slot) 
then I would expect the USB memory stick to report RMB=1 and ejection 
would only cause the device to remove the media, the device would remain 
in the operating system?s driver stack, and the device would begin 
reporting CHECK CONDITION, NOT READY, MEDIUM NOT PRESENT for TEST UNIT 
READY.

Mike Webster
Western Digital 

From: <t10-bounces at t10.org> on behalf of Curtis Stevens <
curtis.stevens at seagate.com>
Date: Friday, July 17, 2020 at 10:05 AM
To: Kevin D Butt <kdbutt at us.ibm.com>, Paul Suhler <Paul.Suhler at kioxia.com>
Cc: "t10 at t10.org" <t10 at t10.org>, "t10-bounces at t10.org" <
t10-bounces at t10.org>
Subject: Re: [T10] Revisiting the RMB (Removable Medium) bit definition

We had this descussion during the original specification development.  For 
USB, the device controller is removed along with the media.  There is 
nothing present to respond with an RMB bit.  If however, you plug in a USB 
floppy, you can have an RMB bit that enables eject function reporting.


---------------------------------------------
Curtis E. Stevens
Technologist
Seagate Technology

E-Mail: Curtis.Stevens at Seagate.com
Phone: 949-307-5050
 


From:t10-bounces at t10.org<t10-bounces at t10.org> on behalf of Kevin D Butt <
kdbutt at us.ibm.com>
Sent: Friday, July 17, 2020 9:40 AM
To: Paul Suhler <Paul.Suhler at kioxia.com>
Cc: t10 at t10.org<t10 at t10.org>; t10-bounces at t10.org<t10-bounces at t10.org>
Subject: Re: [T10] Revisiting the RMB (Removable Medium) bit definition 

I concur with Curtis and Paul.

Kevin D. Butt
SCSI Architect, Tape Firmware, Data Retention Infrastructure
T10 Standards
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com

=========== Interesting Links ===========
[ IBM Tape Storage ]  https://www.ibm.com/it-infrastructure/storage/tape
[ SSIC - HBA/OS/Switch/Product interoperation ] 
https://www-304.ibm.com/systems/support/storage/ssic/interoperability.wss
[ LTO & 3592 ISV Support Matrix ] 
www.ibm.com/systems/resources/lto_isv_matrix.pdf
[ LTO SCSI Reference ] 
http://www-01.ibm.com/support/docview.wss?uid=ssg1S7003556
[ 3592 SCSI Reference ] 
http://www-01.ibm.com/support/docview.wss?uid=ssg1S7003248
===================================



From:        Paul Suhler <Paul.Suhler at kioxia.com>
To:        "Ballard, Curtis C (HPE Storage)" <curtis.ballard at hpe.com>, 
Ralph Weber <Ralph.Weber at wdc.com>, "t10 at t10.org" <t10 at t10.org>
Date:        07/17/2020 09:19
Subject:        [EXTERNAL] Re: [T10] Revisiting the RMB (Removable Medium) 
bit definition
Sent by:        t10-bounces at t10.org


  

I agree with Curtis about the need to be able to report NOT READY, MEDIUM 
NOT PRESENT. I?ve worked on both SSC and SBC devices like that.

Paul
Kioxia

From:t10-bounces at t10.org <t10-bounces at t10.org> On Behalf Of Ballard, 
Curtis C (HPE Storage)
Sent: Friday, July 17, 2020 9:54 AM
To: Ralph Weber <Ralph.Weber at wdc.com>; t10 at t10.org
Subject: Re: [T10] Revisiting the RMB (Removable Medium) bit definition

Ralph,

That bit is used with tape drives and was used with SCSI magneto optical 
drives, DVD drives, etc. 

Even system I?ve used with that bit set to one, and I?ve worked with 
several devices from different manufacturers that set that bit to one, 
only use it in reference to the media with no device server disruption 
other than the expected Unit Attention condition transitions as the media 
is removed and re-loaded.

SCSI devices should only set that bit to one if they are able to report an 
02h/3Ah/00h ? NOT READY, MEDIUM NOT PRESENT

Curtis Ballard
Hewlett Packard Enterprise

From:t10-bounces at t10.org<t10-bounces at t10.org> On Behalf Of Ralph Weber
Sent: Thursday, July 16, 2020 5:27 PM
To: t10 at t10.org
Subject: [T10] Revisiting the RMB (Removable Medium) bit definition

Regarding the Standard INQUIRY data RMB bit, SPC-6 r02 says?
?A removable medium (RMB) bit set to zero indicates that the medium is not 
removable. A RMB bit set to one indicates that the medium is removable.?

An interesting debate has developed regarding whether a USB ?memory stick? 
is an RMB=0 or an RMB=1 device.

One wag has suggested that the RMB bit definition be conditionalized on 
the presence/absence of a coincident Logical Unit Reset condition or I_T 
Nexus Loss condition, something along the lines of?
?A removable medium (RMB) bit set to zero indicates that the medium is not 
removable without resulting in a Logical Unit Reset condition (see SAM-6) 
or an I_T Nexus Loss condition (see SAM-6). A RMB bit set to one indicates 
that the medium is removable with no concurrent Logical Unit Reset 
condition or I_T Nexus Loss condition.?

How says the T10 body politic?

Thanks,

.Ralph_______________________________________________
T10 mailing list
T10 at t10.org
https://www.t10.org/mailman/listinfo/t10

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