RA60 RA80 And RA81 Disk Drives Brochure Aug82

This document, published in August 1982 by Digital Equipment Corporation (DEC), introduces the Digital Storage Architecture (DSA) and its initial product family: the UDA50 Disk Controller and the RA60, RA80, and RA81 Disk Drives.

The Digital Storage Architecture (DSA) is presented as a foundational approach for storage subsystem design in the 1980s, aiming to provide flexible, expandable, and migratable products with optimized data integrity, throughput, and availability. It emphasizes standardized hardware interconnects, software protocols, and a single operating system driver to ensure future compatibility and lower lifetime cost of ownership.

Key components detailed are:

1. UDA50 Disk Controller: The first implementation of DSA, this "intelligent" controller connects up to four DSA disks. It offloads the host system by managing critical functions such as advanced 170-bit Error Correction Code (ECC), error detection and recovery, sophisticated disk mapping, and performance optimizations like seek ordering, overlapped seeking, and rotational optimization. It supports high disk transfer rates up to 3 MB/sec.

2. RA60 Disk Drive: Positioned as the "Removable Media Solution," it offers 205 Megabytes (MB) of user capacity per drive, with up to 615 MB per cabinet or 820 MB per controller. It is rack-mounted and designed for flexibility and portability of data.

3. RA80 Disk Drive: The "Entry Level DSA Disk," this fixed-media (Winchester) drive provides 121 MB of formatted user capacity per drive, with up to 363 MB per cabinet or 484 MB per controller. It's suggested for 100-200 MB databases and can be paired with removable media for backup.

4. RA81 Disk Drive: Billed as the "Lowest Cost Per Megabyte Solution," this high-capacity fixed-media (Winchester) drive offers 456 MB per drive, scaling up to 1368 MB per cabinet or 1824 MB per controller. A triple-drive option provides almost 1.4 Billion Bytes in a compact footprint.

The document highlights the comprehensive features of the DSA subsystems in terms of data integrity (e.g., advanced ECC, address verification, automatic sector retirement), throughput enhancement (e.g., command queue, overlapped seeking, speed matching buffer), and availability enhancement (e.g., radial interconnect, on-board diagnostics, dual access, bus isolation). It also includes detailed specifications and a "Shopper's Guide" emphasizing the importance of lifetime cost of ownership over initial purchase price.