MMC4 SET CD SPEED change to SET SPEED

Bmcferrin at aol.com Bmcferrin at aol.com
Mon Sep 1 22:59:07 PDT 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* Bmcferrin at aol.com
*

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MMC WG Members:
In order to provide a SET SPEED command that is capable of operating
with multiple media types, a great deal more description is required in
the SET SPEED command.  I never fully developed the proposal.
Furthermore, there appears no demand to complete it.  So, it is simpler
to remove it.  The command returns to SET CD SPEED.

Some additional information:
SET CD SPEED was labelled OBSOLETE in MMC-2.  There were quite a number
of complaints from both hardware and software people.  In MMC-3, SET CD
SPEED was removed from the obsolete list.  The SCS bit was added to the
real-time streaming feature to indicate suport for the command.  SET CD
SPEED has never been specified as mandatory for any media type.

We also received complaints about OBSOLETE - especially with respect to
mode page 2ah.  It was decided that use of obsolete is not the best
choice for MMC.  So after a consultation with Ralph Weber, we invented
LEGACY.  Legacy means that:
1) using the capability is permitted,
2) using the capability is not preferred behavior, and
3) the description of the capability shall not change.

The description of a legacy capability shall be placed in the Legacy
Specifications annex.  That simplifies adherence to #2 and #3.

Kind Regards,
Bill McFerrin



Hello Bill (and David), I do not agree this change done in
"T10/02-187.r0".

Because;

1. MMC4 becomes incompatible with MMC3.

MMC3 "4.2.4 High Speed CD-RW media recording" and "6.4.3.34 Real Time
Streaming Feature (0107h)" says SET CD SPEED command is option for CD.
Also
MMC4 says SET CD SPEED command is option in Real Time Streaming Feature
(0107h). If some media type wants it mandatory, please specify in the
media
specification.

2. SET CD SPEED command has too much trouble to expand for future.

Each CD drive models have different implementation of the parameter e.g.
2353 bytes/scoter v.s. 2048 bytes/scoter, 1024 bytes/1K bytes v.s. 1000
bytes/1K bytes. Software and PC manufacture have different
implementation
requirement to the drive manufacture, so a drive manufacture has
different
combination and can not change the specific implementation for the
specific
customer. Software venders need to have Inquiry database to use
selectable
Write Speed of the specific CD drive. So In MMC3, Get Performance
command
and Set Streaming command were created.

3. No command provides possible Speed parameter list that host can use
in
SET CD SPEED command.

Because Mode Page 2Ah is obsoleted and useless other than CD. And SET CD
SPEED command is not allowed to report any error (drive shall select
some
near Writing Speed for any request), so host can not detect what Write
Speed is selected by device. So host can not user SET CD SPEED command
without drive Inquiry database.

4. SET CD SPEED command can not cover Zone rotation control media.

SET CD SPEED command can not cover DVD-RAM, +RW from the beginning. So
Rob
Sims of HP proposed to create Get Performance command and Set Streaming
command. And DVD Forum group accepted the HP's proposal.

5. T10/02-187.r0 shows that the discussion was technically wrong.

"In Discussion, Set CD Speed:" of section 7.2.3 said "Set Streaming is
described as being associated with the READ (12) with the streaming bit
set
to 1." This is technically wrong. Get Performance command has the
capability to show Streaming (data transfer rate) profile of Zone'ed
media
e.g. DVD-RAM 2,7G, +RW 3G and Sparing Speed drop of Hardware Defect
Management device. Streaming bit setting of Read12 command, Write12
command
have no relationship with the Get Performance command capability. Of
cause,
Streaming bit setting never affect Set Streaming command.

6. An ATAPI tape device uses SET CD SPEED command.

MMC does not cover tape device. I checked T10 document and Minutes from
document.97 to document.03. There is not discussion and specification,
proposal of SET CD SPEED command for tape device. This means SET CD
SPEED
command is vender specific definition for "SCSI Stream Commands - 2"
device. If tape device wants to use SET SPEED command, it shall be
described in SPC or SSC, not in MMC.


Bill, No.1 reason makes me much trouble. Some Logo Licence program and
Customer Test program are based on MMC3 document. So if MMC4 has
incompatible description with MMC3, Market and Customers of MMC drives
are
confused too much. Pioneer can not accept this unreasonable crash.


Best regards,

Keiji Katata
PIONEER CORP.






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MMC WG Members:
 In order to provide a SET SPEED command that is capable of operating = with multiple media types, a great deal more description is required in = the SET SPEED command.  I never fully developed the = proposal.  Furthermore, there appears no demand to complete = it.  So, it is simpler to remove it.  The command returns to = SET CD SPEED.
 
Some additional information:
 SET CD SPEED was labelled OBSOLETE in MMC-2.  There were quite a = number of complaints from both hardware and software people.  In = MMC-3, SET CD SPEED was removed from the obsolete list.  The SCS = bit was added to the real-time streaming feature to indicate suport for = the command.  SET CD SPEED has never been specified as mandatory = for any media type.
 
We also received complaints about OBSOLETE - especially with respect to = mode page 2ah.  It was decided that use of obsolete is not the = best choice for MMC.  So after a consultation with Ralph Weber, we = invented LEGACY.  Legacy means that:
 1) using the capability is permitted,
 2) using the capability is not preferred behavior, and
 3) the description of the capability shall not change.
 
The description of a legacy capability shall be placed in the Legacy = Specifications annex.  That simplifies adherence to #2 and #3.
 
Kind Regards,
 Bill McFerrin
 

Because;
 
1. MMC4 becomes incompatible with MMC3.
 
MMC3 "4.2.4 High Speed CD-RW media recording" and "6.4.3.34 Real = Time
 Streaming Feature (0107h)" says SET CD SPEED command is option for CD. = Also
 MMC4 says SET CD SPEED command is option in Real Time Streaming = Feature
 (0107h). If some media type wants it mandatory, please specify in the = media
 specification.
 
2. SET CD SPEED command has too much trouble to expand for future.
 
Each CD drive models have different implementation of the parameter = e.g.
 2353 bytes/scoter v.s. 2048 bytes/scoter, 1024 bytes/1K bytes v.s. = 1000
 bytes/1K bytes. Software and PC manufacture have different = implementation
 requirement to the drive manufacture, so a drive manufacture has = different
 combination and can not change the specific implementation for the = specific
 customer. Software venders need to have Inquiry database to use = selectable
 Write Speed of the specific CD drive. So In MMC3, Get Performance = command
 and Set Streaming command were created.
 
3. No command provides possible Speed parameter list that host can use = in
 SET CD SPEED command.
 
Because Mode Page 2Ah is obsoleted and useless other than CD. And SET = CD
 SPEED command is not allowed to report any error (drive shall select = some
 near Writing Speed for any request), so host can not detect what = Write
 Speed is selected by device. So host can not user SET CD SPEED = command
 without drive Inquiry database.
 
4. SET CD SPEED command can not cover Zone rotation control media.
 
SET CD SPEED command can not cover DVD-RAM, +RW from the beginning. So = Rob
 Sims of HP proposed to create Get Performance command and Set = Streaming
 command. And DVD Forum group accepted the HP's proposal.
 
5. T10/02-187.r0 shows that the discussion was technically wrong.
 
"In Discussion, Set CD Speed:" of section 7.2.3 said "Set Streaming = is
 described as being associated with the READ (12) with the streaming bit = set
 to 1." This is technically wrong. Get Performance command has the
 capability to show Streaming (data transfer rate) profile of Zone'ed = media
 e.g. DVD-RAM 2,7G, +RW 3G and Sparing Speed drop of Hardware Defect
 Management device. Streaming bit setting of Read12 command, Write12 = command
 have no relationship with the Get Performance command capability. Of = cause,
 Streaming bit setting never affect Set Streaming command.
 
6. An ATAPI tape device uses SET CD SPEED command.
 
MMC does not cover tape device. I checked T10 document and Minutes = from
 document.97 to document.03. There is not discussion and = specification,
 proposal of SET CD SPEED command for tape device. This means SET CD = SPEED
 command is vender specific definition for "SCSI Stream Commands - = 2"
 device. If tape device wants to use SET SPEED command, it shall be
 described in SPC or SSC, not in MMC.
 

Bill, No.1 reason makes me much trouble. Some Logo Licence program = and
 Customer Test program are based on MMC3 document. So if MMC4 has
 incompatible description with MMC3, Market and Customers of MMC drives = are
 confused too much. Pioneer can not accept this unreasonable crash.
 

Best regards,
 
Keiji Katata
 PIONEER CORP.
 


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