# DG/UX

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**DG/UX** is a discontinued [Unix](/source/Unix) [operating system](/source/Operating_system) developed by [Data General](/source/Data_General) for its [Eclipse MV](/source/Eclipse_MV) [minicomputer](/source/Minicomputer) line, and later the [AViiON](/source/Aviion) [workstation](/source/Workstation) and [server](/source/Server_(computing)) line (both [Motorola 88000](/source/Motorola_88000) and [Intel](/source/Intel) [IA-32](/source/IA-32)-based variants).

## Overview

By 1985 most computer companies offered [Unix](/source/Unix) as an alternative to their [proprietary operating systems](/source/Proprietary_software).[1] DG/UX 1.00, released by [Data General](/source/Data_General) in March 1985, was based on [UNIX System V](/source/UNIX_System_V) Release 2 with additions from [4.1BSD](/source/BSD). By 1987, DG/UX 3.10 had been released, with [4.2BSD](/source/4.2BSD) [TCP/IP](/source/Internet_protocol_suite) networking, [NFS](/source/Network_File_System) and the [X Window System](/source/X_Window_System) included. DG/UX 4.00, in 1988, was a comprehensive re-design of the system, based on [System V Release 3](/source/System_V_Release_3), and supporting [symmetric multiprocessing](/source/Symmetric_multiprocessing) on the Eclipse MV. The 4.00 [filesystem](/source/Filesystem) was based on the [AOS/VS II](/source/AOS/VS_II) filesystem and, using the logical disk facility, could span multiple disks. DG/UX 5.4, released around 1991, replaced the legacy Unix file [buffer cache](/source/Buffer_cache) with unified, demand paged [virtual memory](/source/Virtual_memory) management. Later versions were based on [System V Release 4](/source/System_V_Release_4).

On the AViiON, DG/UX supported [multiprocessor](/source/Multiprocessor) machines at a time when most variants of Unix did not. The operating system was also more complete than some other Unix variants; for example, the operating system included a full [C](/source/C_(programming_language)) compiler ([gcc](/source/GNU_Compiler_Collection)) and also a logical volume manager. The OS was small and compact, but rich in features. It was simple and easy to install and did not require vast resources of memory or processing power. For example, a six-way [Pentium Pro](/source/Pentium_Pro)-based AViiON would support several hundred users using [text terminals](/source/Text_terminal).

The [volume manager](/source/Logical_volume_management) built into the OS was simple, but very powerful. All disk administration could be performed online, without taking any file system offline. This included extending, relocating, [mirroring](/source/Disk_mirroring) or shrinking. The same functions could be performed on the [swap](/source/Swap_partition) area, allowing in-place migrations of disk storage without downtime. DG/UX 5.4 supported filesystem shrinking, "split mirror" online backup, filesystems up to 2 TB, and [filesystem journaling](/source/Filesystem_journaling) in 1991. Few vendors offered similar features at that time.

DG/UX had a high-performance and stable clustered filesystem. The [Clariion](/source/Clariion) storage [NAS](/source/Network-attached_storage) was connected by high-voltage [SCSI](/source/SCSI) controllers, and SCSI hubs. Each server had double SCSI controllers for [failover](/source/Failover) reasons. Both controllers were master on the same bus, at the same time these filesystems were [NFS](/source/Network_File_System)-mounted from the cluster-master's floating [IP address](/source/IP_address). The data was written from each cluster node directly by the SCSI bus, but the orchestration, the [inode](/source/Inode) tables, where written by the NFS-mount from each cluster member.

Later versions added support for [processor and memory affinity](/source/Processor_affinity) to support their high-end multiprocessor [NUMA](/source/Non-uniform_memory_access) AViiON system.

## References

1. Desmond, John (1985-05-20). ["Prime adds Unix environment for 50 series users"](https://books.google.com/books?id=ygHfUXZWXlcC&pg=PA7). *Computerworld*. Vol. XIX, no. 20. p. 7. Retrieved 2025-06-07.

- ["DG-UX 4.00: DG's redesigned kernel lays the foundation for future UNIX systems"](https://web.archive.org/web/20070930212358/http://www.accessmylibrary.com/coms2/summary_0286-9202012_ITM). Archived from [the original](http://www.accessmylibrary.com/coms2/summary_0286-9202012_ITM) on 2007-09-30.

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Adapted from the Wikipedia article [DG/UX](https://en.wikipedia.org/wiki/DG%2FUX) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/DG%2FUX?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.