SCSI-2 Parity Errors

Gerry Johnsen gerry at
Thu Mar 16 14:43:44 PST 1995

As a manufacurer of both SCSI host adapters and SCSI targets, disk 
arrays, I wholeheartedly agree with Jim McGrath's comments pertaning 
to the uselessness of complicated error recovery procedures ala 
restore pointers message.  In our target devices, and most current 
drives we have tested, a command or data out parity error results only 
in the return of a check condtion status and appropriate sense data.  
Our host adapter experiance with the restore pointers operation 
particularly when combined with scatter/gather transfers indicated it 
was more trouble to impliment then it is worth.

Since most parity errors result from improper cabling or termination 
forwarding the error to the host for action makes the most sense.

Since this subject has generated so much traffic, I would like to 
gauge support for a simplified SCSI-3 document which would describe 
only the most basic subset of features required to impliment a 
host adapter to drive SPI connection.  I have considerable sympathy 
for the engineer assigned to connect a drive to his host system 
who needs to wade through 1000's of pages on multiple SCSI-3 documents 
to do his job. 

Gerry Johnsen				Ciprico Inc
(612)551-4000				2800 Campus Drive
gerry at			Plymouth, MN 55418

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