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Error Symptom Code Generator for a Storage System

IP.com Disclosure Number: IPCOM000077501D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 56K

Publishing Venue

IBM

Related People

Salmassy, OE: AUTHOR [+2]

Abstract

A storage control unit, through hardware detection and microprogram sensing of subsystem error conditions, is capable of providing detailed diagnostic information to the I/O channel and the computer system to which it is attached. This information, contained in sense data, is assembled in a format convenient for and consistent with the particular type or class of subsystem error detected. For example, in a disk storage subsystem, individual sense data formats can be used to describe errors in the following areas of the machine: I/O channel and microprogram loader; disk storage drive; interface between disk storage drive and drive data path; control unit control storage and microinstruction data path; and disk storage drive data.

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Error Symptom Code Generator for a Storage System

A storage control unit, through hardware detection and microprogram sensing of subsystem error conditions, is capable of providing detailed diagnostic information to the I/O channel and the computer system to which it is attached. This information, contained in sense data, is assembled in a format convenient for and consistent with the particular type or class of subsystem error detected. For example, in a disk storage subsystem, individual sense data formats can be used to describe errors in the following areas of the machine: I/O channel and microprogram loader; disk storage drive; interface between disk storage drive and drive data path; control unit control storage and microinstruction data path; and disk storage drive data.

Under each of the formats, a certain number of bytes contain the detailed diagnostic information pertaining to the error condition. The described error symptom code generator automatically generates and places a unique error symptom code directly into the sense data, thus guaranteeing accurate interpretation and saving time required to manually reduce the data.

The error symptom code generator may be microprogram invoked after sense data is assembled following a subsystem error. It generates a symptom code from the diagnostic portion of the sense data, places the code into the sense data and returns control to the main microprogram. Fig. 1 is a representation of the sense data. The format byte FM can be an eight-bit quantity. Bits 0-3 define the format and an error message, generated by microprogram, is in bits 4-7. The diagnostic data bytes A, B, C, D... are variable as to length and makeup, according to the format. The byte are designated A1, B1, C1, if Format = 1; A2, B2, C2, ..., if Format = 2, and so on. Diagnostic information is contained in these bytes. For example: FORMAT 1

BYTE A1

BIT 0 - ERROR COND 1

BIT 1 - UNUSED

BIT 2 - DIAGNOSTIC REG. CHECK BIT

BIT 3 - ERROR COND 2

BITS 4-7 - UNUSED

BYTE B1

BIT 0 - ERROR COND 3...