Save Data Pointer questions
KD6NNM at aol.com
KD6NNM at aol.com
Fri Mar 7 09:06:18 PST 1997
* From the SCSI Reflector (scsi at symbios.com), posted by:
* KD6NNM at aol.com
*
James,
> According to the SCSI-2 rev. H copy of the standard, section 5.6.6 2nd
para.
>
> seems to say there SHALL (on disconnecting devices) be a SAVE DATA POINTER
-
>
> DISCONNECT message after each successful connection (except possibly the
> last). This would say that after the command phase there should be one.
If
>
> one is to look at what the message 02 SAVE DATA POINTER message does, it
> only saves the DATA POINTER not the COMMAND or STATUS pointer, section
> 5.6.20, so it does not make sense for a target to do a 0204 sequence after
> the COMMAND phase, but that's not what the standard says. Generally you
> don't see the SAVE DATA POINTER after
> the COMMAND phase, but it seems I have seen this before. Because there is
> an implied RESTORE pointer message on a reconnect, the COMMAND and STATUS
> (and DATA) pointers are restored to the last saved values, so there is not
a
>
> need to do the SAVE DATA pointer message after the COMMAND phase, but SCSI
> standard does say SHALL send 0204 sequence after all successful
connections.
>
> Your call.
I agree with Jim. I would also "sum it up" as follows:
"When DATA moves --- SAVE DA (DATA) POINTERS!"
"If DATA has NOT moved --- Save or don't. Results are the same.
Greg A.
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