Browse Prior Art Database

SCSI Interface Error Recovery Procedure Method

IP.com Disclosure Number: IPCOM000112129D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Bashem, RB: AUTHOR

Abstract

This invention solves the problems inherent in dealing with multiple exception conditions on the SCSI interface. It is an object oriented approach in which the packages being transferred are stacked.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

SCSI Interface Error Recovery Procedure Method

      This invention solves the problems inherent in dealing with
multiple exception conditions on the SCSI interface.  It is an object
oriented approach in which the packages being transferred are
stacked.

      SCSI Error Recovery Method - The SCSI interface with its
complex message protocol makes error recovery difficult.

Particularly difficult is responding to attention and handling
messages while already in the middle of error recovery.

      This invention solves the problems inherent in dealing with
multiple exception conditions on the SCSI interface.

      The SCSI error recovery method uses an object-oriented error
recovery method.  The object (such as a message element or a data
element) receives the error message and determines what error
recovery is appropriate.

Multiple exception conditions are handled by stacking the objects.

      Error Recovery Control - When an error occurs on the SCSI
interface, the first thing that must be determined is where in the
transfer sequence did the error occur.  This transfer sequence is
represented by a set of objects called Interface Logical Elements
(ILEs), each element representing one phase of the transfer.  For
example, a command phase is represented by a command ILE and a
extended message out is represented by an extended message out ILE.
The transfer sequence is a set of ILEs that the SCSI chip can do all
at once.  (With today's powerful chips that includes a large portion
of the entire command sequence).  I call this entire set of ILEs an
Input Output Package or IO Package.

      Each ILE is responsible for recovering from from exceptions
that occur while it is transfering.  Common exceptions include parity
errors and the initiator...