Known defects in SMC

Erich Oetting x2178 eros at
Fri Dec 17 07:53:16 PST 1999

* From the T10 Reflector (t10 at, posted by:
* Erich Oetting x2178 <eros at>

> I have been making a light review of the tape and medium changer standards.

Thanks, it's always nice to have input like this.

> The following two entries are incorrect in Table 2.  The op codes are 
> duplicated with other legitimate entries.  The text of the standard seems
> be correct (Interpretation Precedence: text before tables).
> RELEASE ELEMENT (6) 16h17h O 6.6
> RELEASE ELEMENT (10) 56h57h O 6.7
> RESERVE ELEMENT (6) 16h O 6.9
> RESERVE ELEMENT (10) 56h O 6.10

This problem was noted earlier. The RELEASE ELEMENT (6) and RELEASE ELEMENT
opcodes are correct (17h and 57h) in ANSI NCITS 314-1998. 
> Since the LOG SELECT command is called out in this draft, the LOG SENSE 
> command must also be called out.  SPC says that if LOG SELECT is
> LOG SENSE shall also be implemented.  
> LOG SENSE support is mandatory in FC-TP, but the SMC standard does not
> it.  This must be fixed.  The entries should be:
> LOG SELECT      4Ch             O           SPC-2
> LOG SENSE           4Dh             O           SPC-2

You are correct here.  No idea why this was not discovered earlier. 

> The FC-TP profile calls out the REPORT LUNS command as mandatory.  This
> does not appear in Table 2.  It must be added.
> REPORT LUNS         A0h             O           SPC-2

The REPORT LUNS command does need to be added to the table.  This was spotted 
earlier, but after SMC was forwarded to ANSI.

> I found another big error in the SMC document.  The document calls out
the REZ
> ERO command as allowed for SMC device servers in Table 2 as optional and 
> refers the reader to SPC (line below taken from Table 2).
> REZERO UNIT     01h     O     SPC
> I have checked both the latest SPC and SPC-2 drafts.  No such command 
> description appears in either document.
> Either this command is unnecessary for SMC, and the entry removed, or there 
> is a big omission in SPC.  
> I suspect that the REZERO command description, if needed, must be added to 
> SMC. There are REZERO commands lurking around in other command set
> left over form SCSI-2 and still implemented by some device servers.
> With the INITIALIZE ELEMENT STATUS command in SMC, the REZERO command may
> be needed; it may simply be removed from the table.  However, such a
> is a technical change that requires some approval (hence the copy to John

The REZERO UNIT command is obsolete and should be removed from the table.

> Also, the FC-TP document seems to require that you reference SPC-2 and
> to permit FC-TP to conform to the base standards.  That document also adds 
> new mode page requirements and commands not called out, etc.  

SPC-2 and FCP-2 did not exist as standards when SMC was forwarded to ANSI.  
SMC-2 will refer to these standards.  I hope to have a draft SMC-2
available by 

the next T10 mailing.

> A thorough review needs to be performed since the base standards have moved 
> and the FC-TP profile appears to require certain behaviors that are found 
> only in the next generation standards.  FC-TP cannot be approved when the 
> base standards do not support the features it requires.  FC-TP is not 
> supposed to define new behavior.
> It appears that there has been no review of SMC vs. the other standards and 
> the requirements of FC-TP.  FC-TP cannot be approved with SMC in this state.

Thanks for your concern.  I will prepare a new revision of an earlier
listing known defects in SMC making note of these additional problems.

  .... Erich

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