Command queuing and SAM - Correction and addendum.
Charles Monia, SHR3-2/W4, 237-6757, email@example.com 11-Feb-1994 1532
monia at starch.enet.dec.com
Fri Feb 11 12:32:02 PST 1994
>From Jum McGrath's reflector note regarding command queuing:
>> Subject: Time: 2:55 PM
>> OFFICE MEMO Command Queuing and SAM Date: 2/8/940
>>Is it required by SAM that any SCSI protocol support all of the traditional
>>queuing functions (e.g. head of queue, ordered, abort, clear queue, etc...). ?
>>It would be a goodness if only unordered queuing and some abort function
>>anyone) be required.
My reply stated in part:
>Although support for queuing is still optional in SCSI-3, SAM requires
>that all SCSI-3 devices which implement queuing support all forms as well as
>the specified task management functions.
The above statement is incorrect. I had assumed that the working group consensus
reached at the last meeting (see X3T10/94-043R0, item 6) specifying that queuing
support was optional, implied that the SCSI-2 implementation rules were in
It is my opinion that, strictly speaking, this is not the case. Furthermore, I
see nothing in the original queuing document ( X3T9.2/91-098R6) passed
by the committee that implies otherwise.
>BTW: I would question why ATA should be bound by the rules that apply to
I am told that ATA(PI) is to be added as one of the SCSI-3 protocols. If that
is the case, then, in my view, ATA(PI) must comply with SAM. Whether this
is desirable or not is, of course, for the committee to decide.
SAM Technical Editor
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