some comments on PLDA tapes using Class 3

Weber, Ralph RWEBER at SCROMPDPST.CO.SYMBIOS.COM
Tue Jul 9 07:11:00 PDT 1996


* From the SCSI Reflector, posted by:
* "Weber, Ralph" <RWEBER at SCROMPDPST.CO.SYMBIOS.COM>
*

Doug,

I wouldn't write a driver to follow case 4 proposed, specifically,

} case                    what the          result of         next
}                         initiator         READ POSITION     initiator
}                         sees              command           action
} =====================================================================
}
} 4. Command and data     command           result is NEW     send next
} succeed, but status     times out         (i.e. expected)   command
} gets lost on the way                      value of
} back to initiator                         position
}
} 5. Failure in command   command           result is OLD     re-send
} or data, and status     times out         value of          command
} gets lost on the way                      position
} back to initiator
}

I'd change case 4 to read:

 case                    what the          result of         next
                         initiator         READ POSITION     initiator
                         sees              command           action
 =====================================================================

 4. Command and data     command           result is NEW     a) backup
 succeed, but status     times out         (i.e. expected)   to OLD value
 gets lost on the way                      value of          of position
 back to initiator                         position          b) re-send
                                                             command

Call me paranoid, but the unexpected position result tells me only that
the tape is not positioned where it ought to be.  Assuming that an
unexpected position result means that the write finished successfully
is, to my mind, wildly optimistic.

Ralph...
 --
Ralph O. Weber                E-Mail: ralph.weber at symbios.com
Symbios Logic Inc.             Voice: 214-733-3594
17304 Preston Road               Fax: 214-713-8121
Suite 635                   SCSI BBS: 719-533-7950 300--14400
Dallas, TX 75252                                   baud







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