DSSI Warm Swapping Guide for BA400-Series Enclosures and KFQSA Adapters

This document outlines the procedures for 'warm swapping'—the process of powering down and replacing specific field-replaceable units (FRUs) on an active Digital Storage Systems Interconnect (DSSI) bus without shutting down the entire VAXcluster. It covers CPUs, KFQSA Q-bus adapters, and Integrated Storage Elements (ISEs) that support this maintenance technique. The manual details requirements, identifies compatible and incompatible hardware, provides step-by-step removal and installation instructions, and includes procedures for recording and restoring necessary system and device parameters to ensure proper system operation post-replacement.