Novell Netware Operating System

[Brian Bezdicek]

NetWare[2] is a discontinued computer network operating system developed by Novell, Inc. It initially used cooperative multitasking to run various services on a personal computer, using the IPX network protocol.

The original NetWare product in 1983 supported clients running both CP/M and MS-DOS, ran over a proprietary star network topology and was based on a Novell-built file server using the Motorola 68000 processor. The company soon moved away from building its own hardware, and NetWare became hardware-independent, running on any suitable Intel-based IBM PC compatible system, and able to utilize a wide range of network cards. From the beginning NetWare implemented a number of features inspired by mainframe and minicomputer systems that were not available in its competitors' products.

In 1991, Novell introduced cheaper peer-to-peer networking products for DOS and Windows, unrelated to their server-centric NetWare. These are NetWare Lite 1.0 (NWL), and later Personal NetWare 1.0 (PNW) in 1993.

In 1993, the main NetWare product line took a dramatic turn when version 4 introduced NetWare Directory Services (NDS, later renamed eDirectory), a global directory service based on ISO X.500 concepts (six years later, Microsoft released Active Directory). The directory service, along with a new e-mail system (GroupWise), application configuration suite (ZENworks), and security product (BorderManager) were all targeted at the needs of large enterprises.

By 2000, however, Microsoft was taking more of Novell's customer base and Novell increasingly looked to a future based on a Linux kernel. The successor to NetWare, Open Enterprise Server (OES), released in March 2005, offers all the services previously hosted by NetWare 6.5, but on a SUSE Linux Enterprise Server; the NetWare kernel remained an option until OES 11 in late 2011.

The final update release was version 6.5SP8 of May 2009; NetWare is no longer on Novell's product list.[3] NetWare 6.5SP8 General Support ended in 2010; Extended Support was available until the end of 2015, and Self Support until the end of 2017. The replacement is Open Enterprise Server.[4]

NetWare evolved from a very simple concept: file sharing instead of disk sharing. By controlling access at the level of individual files, instead of entire disks, files could be locked and better access control implemented. In 1983 when the first versions of NetWare originated, all other competing products were based on the concept of providing shared direct disk access. Novell's alternative approach was validated by IBM in 1984, which helped promote the NetWare product.

Novell NetWare shares disk space in the form of NetWare volumes, comparable to logical volumes. Client workstations running DOS run a special terminate and stay resident (TSR) program that allows them to map a local drive letter to a NetWare volume. Clients log into a server in order to be allowed to map volumes, and access can be restricted according to the login name. Similarly, they can connect to shared printers on the dedicated print server, and print as if the printer is connected locally.

During the early to mid-1980s Microsoft introduced their own LAN system in LAN Manager, based on the competing NBF protocol. Early attempts to compete with NetWare failed, but this changed with the inclusion of improved networking support in Windows for Workgroups, and then the successful Windows NT and Windows 95. NT, in particular, offered a sub-set of NetWare's services, but on a system that could also be used on a desktop, and due to the vertical integration there was no need for a third-party client.

NetWare originated from consulting work by SuperSet Software, a group founded by the friends Drew Major, Dale Neibaur, Kyle Powell and later Mark Hurst. This work stemmed from their classwork at Brigham Young University in Provo, Utah, starting in October 1981.

First called ShareNet or S-Net, this network operating system (NOS) was later called Novell NetWare. NetWare is based on the NetWare Core Protocol (NCP), which is a packet-based protocol that enables a client to send requests to and receive replies from a NetWare server. Initially, NCP was directly tied to the IPX/SPX protocol, and NetWare communicated natively using only IPX/SPX.

The first product to bear the NetWare name was released in 1983. The original product, NetWare 68 (AKA S-Net), ran on Novell's proprietary 68000-based file server hardware, and used a star network topology. This was later joined by NetWare 86, which could use conventional Intel 8086-based PCs for the server. This was replaced in 1985 with Advanced NetWare 86, which allowed more than one server on the same network. In 1986, after the Intel 80286 processor became available, Novell released Advanced NetWare 286. Two versions were offered for sale; the basic version was sold as ELS I, plus an enhanced version, ELS II. *ELS* stood for "Entry Level System".

Advanced NetWare version 2.x, launched in 1986, was written for the then-new 80286 CPU. The 80286 CPU features a new 16-bit protected mode that provides access to up to 16 MiB RAM as well as new mechanisms to aid multi-tasking. (Prior to the 80286, PC CPU servers used the Intel 8088/8086 8-/16-bit processors, which are limited to an address space of 1 MiB with not more than 640 KiB of directly addressable RAM.) The combination of a higher 16 MiB RAM limit, 80286 processor feature utilization, and 256 MB NetWare volume size limit (compared to the 32 MB that DOS allowed at that time) allowed the building of reliable, cost-effective server-based local area networks for the first time. The 16 MiB RAM limit was especially important, since it makes enough RAM available for disk caching to significantly improve performance. This became the key to Novell's performance while also allowing larger networks to be built.

The server could support up to four network cards,[6] and these can be a mixture of technologies such as ARCNET, Token Ring and Ethernet. The operating system is provided as a set of compiled object modules that required configuration and linking. Any change to the operating system requires a re-linking of the kernel. Installation also requires the use of a proprietary low-level format program for MFM hard drives called COMPSURF.

NetWare 2.x implements a number of features inspired by mainframe and minicomputer systems that were not available in other operating systems of the day. The System Fault Tolerance (SFT) features includes standard read-after-write verification (SFT-I) with on-the-fly bad block re-mapping (at the time, disks did not have that feature built in) and software RAID1 (disk mirroring, SFT-II). The Transaction Tracking System (TTS) optionally protects files against incomplete updates. For single files, this requires only a file attribute to be set. Transactions over multiple files and controlled roll-backs are possible by programming to the TTS API.

NetWare 286 2.x normally requires a dedicated PC to act as the server, where the server uses DOS only as a boot loader to execute the operating system file .mw-parser-output .monospacedfont-family:monospace,monospaceNET$OS.EXE. All memory is allocated to NetWare; no DOS ran on the server. However, a "non-dedicated" version was also available for price-conscious customers. In this, DOS 3.3 or higher remains in memory, and the processor time-slices between the DOS and NetWare programs, allowing the server computer to be used simultaneously as a network file server and as a user workstation. Because all extended memory (RAM above 1 MiB) is allocated to NetWare, DOS is limited to only 640 KiB; expanded memory managers that used the MMU of 80386 and higher processors, such as EMM386, do not work; 8086-style expanded memory on dedicated plug-in cards is possible however. Time slicing is accomplished using the keyboard interrupt, which requires strict compliance with the IBM PC design model, otherwise performance is affected.

Server licensing on early versions of NetWare 286 is accomplished by using a key card. The key card was designed for an 8-bit ISA bus, and has a serial number encoded on a ROM chip. The serial number has to match the serial number of the NetWare software running on the server. To broaden the hardware base, particularly to machines using the IBM MCA bus, later versions of NetWare 2.x do not require the key card; serialised license floppy disks are used in place of the key cards.

A key feature was support for 32-bit protected mode, eliminating the 16 MiB memory limit of NetWare 286 and therefore allowing larger hard drives to be supported (since NetWare 3.x cached the entire file allocation table and directory entry table into memory for improved performance).

NetWare version 3.x was also much simpler to install, with disk and network support provided by software modules called a NetWare Loadable Module (NLM) loaded either at start-up or when it was needed. NLMs could also add functionality such as anti-virus software, backup software, database and web servers. Support for long filenames was also provided by an NLM.

In NetWare 386 3.x all NLMs ran on the server at the same level of processor memory protection, known as "ring 0". This provided the best possible performance, it sacrificed reliability because there was no memory protection, and furthermore NetWare 3.x used a co-operative multitasking model, meaning that an NLM was required to yield to the kernel regularly. For either of these reasons a badly behaved NLM could result in a fatal (ABEND) error.

For a while, Novell also marketed an OEM version of NetWare 3, called Portable NetWare, together with OEMs such as Hewlett-Packard, DEC and Data General, who ported Novell source code to run on top of their Unix operating systems. Portable NetWare did not sell well.

Version 4 in 1993 introduced NetWare Directory Services, later re-branded as Novell Directory Services (NDS), based on X.500, which replaced the Bindery with a global directory service, in which the infrastructure was described and managed in a single place. Additionally, NDS provided an extensible schema, allowing the introduction of new object types. This allowed a single user authentication to NDS to govern access to any server in the directory tree structure. Users could therefore access network resources no matter on which server they resided, although user license counts were still tied to individual servers. (Large enterprises could opt for a license model giving them essentially unlimited per-server users if they let Novell audit their total user count.)

c80f0f1006