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

Kevin D Butt kdbutt at us.ibm.com
Wed Jul 29 08:48:45 PDT 2020


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 RMB should 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 ADDITIONALSENSECODE field (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 20-082r0 SPC-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_______________________________________________
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