de facto obsolete sbc-2 ops

Elliott, Robert Robert.Elliott at COMPAQ.com
Tue Feb 19 11:51:45 PST 2002


* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert" <Robert.Elliott at COMPAQ.com>
*
> -----Original Message-----
> From: Pat LaVarre [mailto:LAVARRE at iomega.com]
> Sent: Tuesday, February 19, 2002 10:52 AM
> To: t10 at t10.org
> Subject: de facto obsolete sbc-2 ops
> 
> Q1) Do sbc-2 folk hang out here at <t10 at t10.org>?
> 
> > The following operation codes
> > are vendor-specific: ... 23h ...
> 
> Q2) I wish.  Has the time come to acknowledge Microsoft's de 
> facto definition of this op?  Can we make x23 "obsolete" 
> rather than "vendor-specific"?

The usual rule is once vendor-specific, always vendor-specific.  

MMC3 defines 23h as "READ FORMAT CAPACITIES". Is it being used on block
devices too? SCSI-2, SBC-1, and SBC-2 all mark it as vendor-specific for
block devices. 

> > ...
> 
> Q3) Can we obsolete x8B?  On the theory that for some people 
> this will be the Seek op for 64-bit Lba's?

16-bit opcodes are a rare commodity; we don't want to discard them just
because the lower bits match some other opcode's lower bits (SEEK(6) at
0Bh and SEEK(10) at 2Bh).


> Thanks in advance.    Pat LaVarre
> 
> P.S.
> > 5.1.43 XDWRITEREAD (32) command
> > This command is only available
> > on transport protocols supporting bidirectional commands.
> 
> Fun, thank you.  I had heard rumour of devices moving out 
> more than the 16 byte Cdb length limit of Atapi/Usb etc. and 
> I had heard rumours of commands that move data both in & out, 
> but this is very concrete.

You may want to peruse the OSD command set, which has lots of long CDBs
and discusses using bidirectional for its CREATE command.

---
Rob Elliott, Compaq Server Storage
Robert.Elliott at compaq.com

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