DSA Troubleshooting Course Student Guide Mar89

This document is a Student Guide for the DSA (Digital Storage Architecture) Troubleshooting Course, published by Digital Equipment Corporation in March 1989. It is explicitly designated for DIGITAL INTERNAL USE ONLY and intended for field engineers as both a learning tool and a reference for troubleshooting problems in the field.

The guide provides a comprehensive overview of DSA disk subsystems, focusing primarily on RA-series disk drives (RA60, RA70, RA80, RA81, RA82, RA90) and associated HSC/xDA controllers within a VMS operating system environment.

Key areas covered include:

1. Digital Standard Disk Format (DSDF): Detailed explanations of disk physical geometry, logical addressing (Logical Block Numbers - LBNs, Replacement Block Numbers - RBNs, Diagnostic Block Numbers - DBNs, External Block Numbers - XBNs), data structures (headers, Error Correcting Code - ECC, Error Detecting Code - EDC), and servo information.
2. Bad Block Replacement (BBR) and Revectoring: Mechanisms for handling defective disk blocks, including when and how BBR is performed, and discussions on primary and non-primary replacement types.
3. Standard Disk Interface (SDI): A thorough description of the communication protocol between controllers and drives, covering SDI bus lines, encoding, various drive states, and Level 1 and Level 2 SDI commands.
4. Drive Characteristics and Status Decoding: Detailed specifications for different RA-series drives and methods for decoding drive status bytes to identify error conditions.
5. Troubleshooting Utilities and Diagnostics: In-depth user guides and lab exercises for critical tools:
   • BLOCK.COM: A utility for logical block number conversion.
   • DKUTIL (Disk Utility): For examining and modifying disk structures, particularly the Replacement Control Table (RCT) and Format Control Table (FCT).
   • RAUTIL: A VAX/MicroVAX VMS utility for media analysis, bad block replacement, and LBN/RBN translation.
   • DSAERR: An error log analysis tool for processing VMS binary error log files and generating various reports (Physical, Geographic, Summary, Verbose, Time).
   • VAXsimPLUS: An Artificial Intelligence (AI) based tool for symptom-directed diagnosis, providing predictive analysis and formatted evidence data.
   • FAKDSK: A utility for creating "fake" disk units on HSC controllers for testing purposes.
   • RA Drive Formatting: Guidance on when and when not to use disk formatting as a troubleshooting and recovery measure.

The document emphasizes a "symptom-directed" troubleshooting approach, leveraging existing error log information and systematic data collection, analysis, and verification steps to minimize disruption. It specifically states that it does not cover MSCP (Mass Storage Control Protocol), specific controller or drive repair (beyond HDA and communication references), physically broken equipment (emphasis is on logically broken drives), or tape drive support.