Novell NetWare

NetWare is network operating system and a set of network protocols which are used in this system for interaction with the computers clients connected to network. The NetWare operating system is created by Novell company. NetWare is the closed operating system using cooperative multitasking for accomplishment of different services on computers with architecture of Intel x86. The stack of the XNS protocols is the cornerstone of network protocols of a system. Now NetWare supports the TCP/IP and IPX/SPX protocols. NetWare is one of families of XNS systems. For example, Banyan VINES and Ungerman-Bass Net/One belong to such systems. Unlike these products and XNS, the NetWare system occupied an essential market share in the early nineties and sustained the competition to Microsoft Windows NT after which release other systems competing with it stopped the existence.

Very simple idea was the basis for NetWare: one or several dedicated servers are connected to network and provide for sharing the disk space in the form of "volumes". On computers clients with the MS-DOS operating system several special resident programs which allow "appoint" letters of disks to volumes are started. Users need to be registered in network to get access to volumes and to have an opportunity to appoint letters of disks. Access to network resources is defined by a registration name.

Users can be also connected to shared printers on a dedicated server and print on network printers as well as on local.

In spite of the fact that in early versions of NetWare all system modules were considered as unreliable (any incorrectly working module could break work of all system), it was very stable system. Cases when the NetWare servers work without intervention of the person for years are frequent.

History

The NetWare system was created as a result ofSuperSet Software work  — consulting the group based by friends Drew Meydzher Dale Naybauer, Kyle Powell and later entered into this group Mark Hirst. Results of their occupations in Brigham Young University in the city Provo, the state Utah in October were the basis for this work 1981.

In  1983 Raymond Noorda joined work of the SuperSet group. Originally the group was faced by a problem of creation of the CPM system of sharing of disks for networks on the basis of the equipment of CP/M which was sold at that time by Novell company. In group there was a belief that CP/M is the platform doomed to failure, and the alternative solution for just released IBM compatible PCs was as a result proposed. The group also wrote the Snipes application  — the game working in an alpha mode which they used for testing of new network and demonstration of its opportunities. Snipes was the first network application in the world and actually is a predecessor of many popular multiplayer games, such as Doom and Quake. [1]

This network operating system was called Novell NetWare later. In NetWare the protocol NCP ({ is used { lang-en|NetWare Core Protocol}}  — the core protocol NetWare) which is the transfer protocol of packets allowing clients to transfer requests for the NetWare servers and to receive from them answers. Originally NCP was tied to protocols IPX/SPX, i.e. the NetWare system in itself could use for interaction in network only of IPX/SPX. For information storage authentications the built-in system on a basis was used DBMS Btrieve.

The first software product with the name NetWare was released in  1983. It was called NetWare 68 (or Novell S-Net), worked on the processor of Motorola 68000 and used topology "star". This product was replaced in  1985 with NetWare 86 which was written for work on processors Intel 8086. After release of processor Intel 80286 the Novell company released NetWare 286 (in  1986). In  1989, after release of processor Intel 80386, NetWare 386 followed. Later Novell reviewed numbering of versions of NetWare: NetWare 286 became NetWare 2.x, and NetWare became NetWare 3.x.

NetWare 286 2.x

The NetWare setup of version 2 required considerable efforts: for any change it was necessary to recompile a core and to reboot a system. Recompilation and replacement of a core required serial use of 20 diskettes. Administration of NetWare was executed using text utilities, for example SYSCON. In NetWare 2 the NetWare File System 286 file system, or NWFS 286 was used.

NetWare 3.x

NetWare of version 3 was simplified due to creation by to modular the principle. Functions of the operating system were performed by separate software modules  — loadable modules of NetWare (NLM) which could be loaded as at start of a system, and as required after start. Such architecture allowed to add necessary functions to a system, such as antivirus protection backup, support of long names files (at that time names of files in widespread MS-DOS are limited to 8 characters of a name and 3 characters expansions of a name) or support of files Macintosh. Management of NetWare was still offered to be executed in text utilities. In NetWare 3.x there was a new file system which was used by default in all NetWare systems to NetWare 5.x  — Netware File System 386, or NWFS 386.

Originally in NetWare for authentication the service Bindery was used. It was a system in which all data on access rights of users and these systems of protection were stored separately on each server. When in network there were several servers, users needed to be registered in each of these servers separately, and each server had to contain the list of users with access rights.

NetWare 4.x

Version 4 in  1993 provided a directory service of Novell (NDS)  — the service Bindery was replaced with service of the global directory in which all network infrastructure was described and which was controlled from one point. It meant what to the user was to be authenticated in NDS once enough to get access to resources of any server in structure of a tree of the directory. Thus users could get access to network resources regardless of on what server these resources were located. In version 4 a number of useful components and utilities, such as service of the distributed printing of Novell (NDPS), support of Java and the opened/closed enciphering of RSA also appeared.

NetWare 4.1x

NetWare 4.11 (intraNetWare release 1996.) included a number of the improvements which allowed to simplify installation of the operating system and its management and also to make it faster and stable. With this version also the first completely 32-bit client for workstations Microsoft Windows and the NetWare Administrator utility (NWADMIN or NWADMN32) — graphic the utility of administration NetWare was delivered. At that time the Novell company still saved a binding of the system to a stack of protocols of IPX/SPX as the NCP protocol was supported only with this stack. However thanks to increase in popularity TCP/IP NetWare 4.11 included a number of components and utilities which allowed intranets to create and connect local networks to To the Internet. With the operating system means for connection of workstations IPX to networks IP, for example the gateway IPX/IP were delivered. The Novell company for the first time included in delivery the application Web server (привет) which allowed to organize websites based on the NetWare servers. In this version integration of Internet technologies, for example by implementation of protocols DHCP and DNS on the NetWare platform also began.

In the same time the Novell company intensified works on integration of the products with a directory service of NDS. The mail GroupWise system was integrated with NDS, and the Novell company released some other products with support of the directory: ZENworks, BorderManager, Novell Modular Authentication Services and others.

NetWare 5.x

With release in  October, 1998 NetWare 5, Novell company recognized a crucial role of the Internet and made the main for the NCP protocol support of a stack of TCP/IP, but not IPX/SPX. The stack of protocols of IPX/SPX was supported, but TCP/IP began to play a role of the main stack. The majority of utilities of Novell and products of other companies should be rewritten for work with TCP/IP, but not to IPX/SPX. With NetWare 5 the first version graphic was delivered to Java - the administration console  — ConsoleOne which was supposed to be used together with utilities of NWAdmin.

The product NetWare 5 was released during reduction of a market share of NetWare (in the western markets) in process of replacement of the NetWare servers by the Windows NT servers. Also the last update for the NetWare 4 operating system  — NetWare 4.2 was released.

Version 5.1, became the latest version of NetWare 5 provided century January 2000. The product NetWare 5.x included a set of new components, including support SAN and clusters, the new file system NSS (Novell Storage Services) which replaced the traditional NWFS file system, service of certificates, IBM WebSphere, services multimedia, retrieval services on web resources, Oracle 8, Novell SQL, public key infrastructures service (PKIS) and others.

NetWare 6.x

With release in  October, 2001 of NetWare 6, changes were continued: the improved support of symmetric multiprocessor processing (SMP  — several processors in one server), was added by iFolder (file synchronization of the local folder with the server and providing secure access to them in the local area network and via the Internet), iManager (the web utility of administration NetWare and other products), Native File Access Pack (NFAP  — a component, providing access to NetWare server resources to clients of Windows, Macintosh and the UNIX-LIKE systems under protocols of matching networks), NetDrive (the utility allowing to appoint letters of disks to HTTP- and FTP resources and also to the iFolder servers) and also the Web server was by default replaced with Netscape Enterprise Server with Apache. Also the Btrieve database (used with the previous versions of NetWare) was replaced with Pervasive PSQL.

Open Enterprise Server

Основная статья: Novell Open Enterprise Server

1.0

After the version of NetWare 6.5 the Novell company released in  2003 the Open Enterprise Server (OES) operating system from which users can select operating system kernel  — NetWare or /Linux. This integration was executed soon after acquisition by Novell company of Ximian companies and the German supplier of GNU/Linux of SUSE company. It is considered that Novell displaces the attention with NetWare and ports applications on GNU/Linux. Though officially the Novell company denies it and states that it will conduct development and NetWare, and/Linux.

2.0

OES 2 was released October 8 2007. It included NetWare 6.5 SP7 and new, based on Linux  — SLES10.

Performance

The NetWare system dominated in the market of network operating systems from the middle of the 80th years until the end of the 90th thanks to extremely high performance in comparison with other network operating systems. The majority of comparative tests at that time indicated advantage in performance in the ratio from 5:1 to 10:1 in comparison with products of Microsoft, Banyan and other companies. Results of one comparative test were especially interesting: the NetWare 3.x system with the services NFS working under protocols of TCP/IP (not on the IPX protocol drafted for NetWare), was compared to the expensive Auspex NFS dedicated server and to the server of SCO Unix with the started services NFS. Performance of NetWare NFS exceeded performance of both NFS systems which are a part of the corresponding operating systems and exceeded twice performance of SCO Unix of NFS on the identical equipment.

There were several reasons of such performance of NetWare.

Services of files instead of disk services

At the time of development of the first version of NetWare almost all data warehouses in the local area networks worked at a basis of model of the disk server. It meant that the client computer for reading the block of the file had to execute the following requests on rather slow local network.

1. to Read the first block of the directory.
2. to Continue reading the following blocks of directories until the directory block containing data of the required file is found (such blocks of directories it could appear much).
3. to Read blocks of records of files until the block with data of the required file is found (such blocks it could appear much).
4. to Read a required data unit.

In the NetWare system constructed on the basis of model of services of files, customer interaction happened at the level of API of the file interface.

1. to Send a request for opening of the file (if this file was not open yet).
2. to Send a request for required data in this file.

All operations on search of the directory for determination of the place where required data are physically located on a disk, were executed with a high speed locally on the server.

To the middle of the 1980th years the majority of network operating systems began to use model of services of files instead of model of disk services. Now there is a return to model of disk services, for example in SAN.

Efficiency of the NCP protocol

The most part of the network protocols used at the time of development of NetWare did not consider reliable delivery of messages by network. Usually read operation of the file by the client was executed as follows.

1. the Client sent a request for the server.
2. the Server confirmed receiving a request.
3. the Client confirmed receiving confirmation.
4. the Server sent the requested data to the client.
5. the Client confirmed data acquisition.
6. the Server confirmed receiving confirmation.

The concept of safe delivery of packets by network in most cases was the cornerstone of the NCP protocol. Therefore reply to the request served in most cases as confirmation. An example of a request of reading the client in this model.

1. the Client sent a request for the server.
2. the Server sent the requested data to the client.

All requests contained the sequential number therefore if the client did not receive the answer during the specified time, he sent a request repeatedly with the same sequential number. If the server already processed this request, he resent the cached answer. If the server had no time for processing of a request, he sent "positive confirmation" that meant "I received a request, but did not reach its processing yet, do not disturb me".

Reduction by two thirds of network traffic and the related delays was result of use of this model of "trusted network".

The operating system without preemptive multitasking developed for network services

In the nineties execution of operations of network file services by the special software in normal the operating system was intensively compared to accomplishment of the same transactions by the specialized operating system. NetWare was the specialized operating system, not the operating system with support of a partitioned mode of time. It was completely written for request processing like "client-server". Initially a system was focused on services of files and printing, but showed excellent legacy opportunities as the platform databases, systems e-mail, web services and other services later. It also effectively worked as router protocols IPX, TCP/IP and AppleTalk though never applied for the flexibility inherent in hardware routers.

In version 4.x and earlier versions of NetWare preemptive multitasking, time partitioned mode, a virtual memory, the graphic user interface and other was not supported. The processes and services executed in NetWare should were work correctly: process a request and return management to the operating system in the allowed time. Unlike NetWare operating systems of general purpose (UNIX, Microsoft Windows) were based on interactive model with support of a partitioned mode of time when without control from the operating system the program could occupy all available resources of a system. In such environments with preemptive multitasking and virtualization of memory there was considerable additional loading as in such systems there are never enough resources for accomplishment of all requests of all applications. Such systems improved by closer integration of network services with operating system kernel of "general purpose" over time, but could not reach the level of efficiency NetWare. Unfortunately, earlier, when applied processes managed themselves, such "trust" often led to abnormal stops of a system.

Perhaps, more effective work of NetWare in comparison with operating systems of general purpose was a basic reason of success of Novell in 80th and 90th. However in process of increase in power of microprocessors the value of efficiency became less and less, and with the advent of the Pentium processor for NetWare its advantages began to outweigh complexity of management and application development. Self-confidence of marketing division and the management of Novell against the background of real threat of competitors (NT4 and Microsoft Exchange) became a last straw in process which, eventually, led to loss of positions the NetWare system.