Untagged tasks?

Bob Snively Bob.Snively at EBay.Sun.COM
Fri Mar 31 12:22:10 PST 2000

* From the T10 Reflector (t10 at t10.org), posted by:
* Bob Snively <Bob.Snively at EBay.Sun.COM>

Having received the proper amount of well-justified flack, I am proposing
that the untagged queueing not be made obsolete, using the accompanying 
language.  The reasoning is:

	1)  Simple queued and untagged devices actually act the same,
	    except that untagged operations are checked for command overlap.

	2)  Support of untagged queueing is mandatory in SAM-2.
	3)  Untagged queueing is widely used in tape and library applications.
	    Since the bits will be set, it is important to continue to
	    define their usage.
	4)  Same as 3, but for booting.

The wording I placed in 150r2 is:


  (T) Page 37 - section - The untagged task option should be make 
  obsolete in FCP-2 as it serves no useful purpose.


  This proposal is rejected. SAM-2 unambiguously requires a protocol to support  
  both tagged and untagged tasks. Tape functionality is almost exclusively 
  implemented with untagged tasks. Boot functionality is almost exclusively 
  implemented with untagged tasks. While the use of that attribute may not 
  create a meaningful difference in the behavior of the devices, the attribute 
  will absolutely be used by present day drivers and must be supported.

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