COMP 2122 Network Operating Systems Richard Henson University

COMP 2122 Network Operating Systems Richard Henson University of Worcester November 2010

Week 6: Overview of Important Network Operating Systems • Objective: Ø Name significant network operating systems in developments towards today’s local area networks Ø Briefly explain features of proprietary products that fulfil particular requirements of a network operating system Ø Link operating system architectures to the seven layer model

Early Operating Systems • • Early computers were all unique and had their own operating systems IBM designed & built the world’s first mass produced “mainframe” Ø IBM 701 (1952) • purchasers expected to write their own operating systems! • first “mass produced” operating system written by General Motors: GM-NAA I/O in 1956 n adopted by IBM as IBSYS Ø IBM hugely successful; by 1980 s, allegedly bigger than US government (? )

First British Operating system • Leo 3 was the first mass produced British Computer Ø 94 units built 1961 -1969 • full list of buyers http: //www. leocomputers. org. uk/newleo 3 s. htm • Ø each had a loudspeaker connected to the CPU… so operators could tell if it was “looping” Ø had a multi-tasking operating system called “master program” some continued in service until 1981

First Minicomputer & Operating system • Produced by Digital Equipment Corporation (DEC) in 1963 Ø called the PDP-6 • “mini” in size compared to mainframes • huge by today's standards Ø operating system called “monitor” • • • evolved into the TOPS 10 (1970) ran on the legendary PDP-10 still going until 1988 can get it even now: http: //www. inwap. com/pdp 10/96 license. txt

Unix • Spin-off (1969) from project MULTICS Ø First attempt at a multiuser operating system • Consortium including Bell Labs, AT&T, n US equivalent of BT at that time • FAILED! Too ambitious… Ø Bell Labs: cut down derivation called UNICS -> UNIX • written in assembly language by Ken Thompson • sharing of processes also being explored in The ARPAnet project • Commercial Challenge: • DEC PDP-7 minicomputer • needed a general purpose “time sharing” operating system for multiuser use… • their own os “monitor” had not yet matured into TOPS-10

Thompson, Ritchie, “B”, NB, “C” & Unix • Thompson looking for a high-level language to develop a time sharing os • briefly toyed with Fortran • worked with colleague Dennis Ritchie to create their own higher level language – “B”, based on BCPL • http: //cm. bell-labs. com/cm/cs/who/dmr/kbman. html • development of B = new. B (NB) • development of NB -> C • Unix kernel was rewritten in “C” (1973)

Development of Unix/C • “C” compiler completed by Ritchie in 1972 • Further commercial Unix versions (for • • Honeywell & IBM) released in 1973 “C” further developed during 1973 -7 Full definition of language as Kernighan & Ritchie “C” (1978) Ø rapidly gained universal acclaim • Unix still written in “C” to present day! Ø 32 -bit processing from the outset

Open Sourceness of Unix • AT&T not allowed to be a commercial company • could not sell Unix • gave a copy away free to any developer who wanted to use it! • many universities contributed to its development • Result (in 1979): Unix version 7 • still recognisable today!

Silicon Valley, TCP/IP and Unix • University of California created The ARPAnet • (1969) 1975 onwards: Berkeley, north of San Francisco • hub for its own unique brand of Unix developments • start of “Silicon Valley” (IT hot spot around SF) • ARPAnet team • • • developed TCP/IP 1980, gained approval through RFC operating system that would support TCP/IP arrived in 1983… • Berkeley Unix (v 4. 2) packaged with TCP/IP protocol stack • Sun microsystems producing the hardware…

Bell Labs Unix becomes Commercial… • US Dept of Justice broke up AT&T in 1984 • Bell Labs then allowed to sell their Unix source code… • Fortunately for SCO (Santa Cruz Operations) they had ported Bell Unix to Intel hardware the previous year (!) • SCO Unix for PC became a lucrative business market • operating system provided security on a PC where DOS couldn’t…

Bad days for Unix… • UNIX free by nature from outset Ønot so on an Intel PC, thanks to SCO!!! ØBell Labs jealously guarded the source code… Øuniversities lost interest • Unix became expensive to buy… and was still not user-friendly or easy to use so even more expensive to own!

Linux • From 1992 (Linus Torvalds, University of Helsinki) made free Unix possible again! Ø LINUX – based on his name… • Took… Ø Stallman’s GNU open source Unix • which Tanenbaum had developed into MINIX… Ø very stable Ø secure file system Ø very efficient, optimised code Ø earlier versions ran on an Intel 486! • Still Unix, still a server-end system Ø for client-server networking, need client-end software: • e. g. Banyan VINES

Linux • Still freely available via Internet! • Huge range of software tools for managing • UNIX networks available for download Problems (compared to Windows): Ø not as easy to manage Ø limited on-screen help Ø limited range of good application software Ø not all hardware has UNIX/LINUX driver software

SCO v Linux (more Unix lawsuits…) • SCO sued Linux in 2003 for misappropriation of Unix System V code Ø subsequently sued: • • • IBM Red Hat (Novell) Anyone else commercially involved with Linux n e. g Daimler. Chrysler • US Court finally shut them up in August 2007 by saying SCO had no rights to the code Novell were using… Ø Linux continues to be “free” to this day…

Unix Platforms in 2010… • Typical hardware Ø SUN SPARC Ø not a PC! • Excellent as an Internet platform Ø very secure, if properly configured • software bugs mostly sorted out a long time ago… • always used TCP/IP for machine-machine communications • Server or standalone workstation mode Ø Linux/Intel favourite for workstation mode

Operating Systems for PC Ethernet Networks • Original Topology (1980 s, early 90 s): Ø bus, coaxial cable & BNC connectors (!) • DOS not designed for server end, or distributed communications… Ø two popular client-server operating systems emerged: • Novell Netware n n IPX/SPX protocol not OSI compliant - proprietary & code secret • DEC (Digital) PCSA n n DECnet protocol OSI compliant - code open source

Novell Netware (version 3) • Netware - late 1980 s Ø Novell’s proprietary IPX/SPX network protocol • network. ID based on MAC address • hardwired into network card during manufacture • Server end… Ø client-server networking only (no peer-peer) Ø secure file system based on user, groups, rights & inherited rights Ø supported mirroring, duplexing, RAID Ø TTS to reverse incomplete transactions Ø network resource names, etc. stored as a separate bindery on each server

Other Features of • I/O optimisation: Ødisk caching Øelevator seeking (disk accesses ordered according to position on disk) Ødirectory hashing ØMHS protocol for message-handling and email within the LAN

Strengths/Weaknesses of Netware 3 • Strengths: Ø fast and secure • awarded Server Fault Tolerance (SFT) grade III, when used with server duplexing • Weaknesses Ø proprietary protocol, not peer-peer Ø inadequate accounting services Ø only 16 -bit processing Ø 250 user maximum Ø each user needs to login to each server

Improvements (version 4) • Scalable across servers Ø Using Network Directory Service (NDS) Ø network info stored in a managed naming system as a bindery across the whole network Ø security includes NDS attributes • LANalyser tool for analysing packets & • identifying protocol problems Easier to use than v 3: GUI-based Ø supported: • • • 32 -bit processing long filenames - like Windows 95 on SMP - symmetric multi-processing (2 processors) Up to 1000 users remote Network mgt

Enduring Problems with Netware • Only ran on Intel Platform • Reliant on DOS/Windows at the client end • NDS not X 500 compliant • not directly compatible with Internet protocols such as TCP/IP Ø based on IPX/SPX protocol (OSI levels 3 and 4) for interprocess communication Ø used MAC addresses (fixed) as unique identifiers, rather than IP addresses • not suitable for peer-peer networking • not pre-emptive in handling processes

What happened to Netware? • V. successful in early 1990 s Ø better sales than DEC PCSA architecture, even though the latter was OSI compliant (!!) • SPX/IPX faster than TCP/IP… Ø 70% of the PC network market • Didn’t see what was coming… Ø DEC mini computers lost market share • everyone wanted a PC network • main rival DEC sold off and “asset stripped” Ø BUT… • • • by 1998, Novell Netware sales were sunk by 2000, even Oracle stopped supporting them only kept in business by merging with Red Hat Linux

What was DEC? • World’s most innovative computer company for many years… Ø first minicomputer: • PDP-1 (Programmable Data Processor) Ø first UNIX/C implementation • On PDP-5 Ø most successful minicomputer: • VAX (Virtual Addresss e. Xtension) Ø first virtual memory operating system • VMS (virtual memory system) for VAX Ø first commercially successful RISC chip • alpha Ø first commercial Internet domain & website Ø first successful search engine: Alta. Vista

Where did DEC go? • Second biggest computer company in the world in 1990! Ø over 100000 employees! Ø With early 90 s recession, went into decline… • New MD in 1992, only accelerated the decline Ø assets sold one by one… • unkindest cut – alpha chip to Intel in 1997 Ø what was left (VMS) went to Compaq in 1998 • sold on to HP… • still support VMS (as Open. VMS) to present day • Why? Ø as with the downfall of IBM and Novell… • perhaps the name Microsoft might help…

What went wrong with DEC? • Now long enough ago to be of historical interest… Ø Dave Cutler, brains behind DEC’s VMS went to work at Microsoft in 1988 to develop “a new operating system” (NT) • • DEC keen to get their alpha chip onto the original Windows NT… • signed away any rights to the code used in creating windows NT • so Microsoft effectively got the technologies behind VMS for free!!!! But thanks to HP, and enthusiastic users, VMS lives Ø available for download at: • http: //www. openvms. compaq. com/openvms/freeware

Microsoft & Operating Systems • Original IBM PC operating system… Ø whilst the US government was being defeated in the courts by IBM… Ø the deal that almost put them out of business was pulled off by the young Bill Gates… • story about IBM negotiations with Bill Gates (regarding his mate Tim Paterson’s os): n http: //inventors. about. com/library/weekly/aa 033099. htm • and the tragedy of Gary Kildall (creator of CP/M)… n http: //www. businessweek. com/magazine/content/04_43/b 390 5109_mz 063. htm

DOS (Desktop Operating System) • As was to be expected from a back-street deal… Ø DOS was an awful operating system… Ø no way it could be satisfactorily used for even multi -tasking, let alone networking… Ø no way of • logging in as an authenticated user… • restricting access to resources… Ø to the new (misguided? ) computer generation… • none of this mattered Ø by the late 1980 s Gates was the 4 th richest person in the world!

OS 2, Windows, and Windows NT • By late 1980 s, PCs being used for serious business purposes Ø IBM needed a serious operating system for the PC… Ø Microsoft worked them on OS 2 Ø still didn’t see Gates as a rival! • At about the same time… Ø Cutler left DEC… joined Microsoft Ø scope for a virtual memory operating system… • (Windows)

Windows • On the one hand ØMicrosoft were working with IBM on OS 2 • One the other hand: Øthey were working on developing Windows • and working with software developers to provide applications for Windows… n users want apps, not operating systems! • Guess which one won? ? ? Øyou’ve got it… Microsoft now bigger than IBM

Windows NT • Windows was based on DOS Ø virtual memory enabled multitasking Ø but fundamentally flawed… • Intermediate towards a new “serious” operating system… • using DEC technology… • “New Technology” operating system quietly released in 1993 Ø as a disguised front end enhancement to Windows 3. 1 • i. e. Windows 3. 11 (for workgroups)

NT Architecture • Industry experts soon noticed that many features were surprisingly similar to VMS… Ø oddity… VMS + 1 = WNT (!!) • But Microsoft’s customers were from a new generation. The commercial product was still basically DOS, but Gates now offered Ø peer-peer networking and a simple network protocol ( Ø user-friendly graphical interface Ø sharing resources on apps Ø even TCP/IP compatibility…

Flexibility of Windows NT (followed the Unix pattern) Applications Operating system functions & interface Operating system kernel hardware

Windows NT v Unix v Netware • By 1994, three possible network platforms: ØNovell: fast, proven, scalable, well established, but proprietary (NDS & IPX/SPX) ØUnix: robust, scalable, open source & Internet ready but complex, & limited apps ØWindows NT: neither robust nor scalable • but Gates by now a past master at exploiting weakness…

Progressive Development of Windows NT Applications (Windows apps -> NT apps) Operating system functions & interface (Windows) os kernel (diff versions of NT available for diff CPUs) range of CPUs, motherboards

NT version 4 • Major leap forward, released late 1996 Ø Windows 95 interface Ø many www features, incl web server • Server end: Ø designed to support server applications • no theoretical limit to number of users Ø now a major challenge to Netware (not TCP/IP compatible) & Unix (still not enough apps) Ø main problem: not scalable • Client end (Workstation/Professional version) Ø designed for client machines or secure peer-peer networks (upgrade of Windows for Workgroups) Ø connectivity now uses TCP/IP as default Ø max 10 concurrent sessions

The 32 -bit Windows NT architecture • Secure kernel based on VMS Ø available for multiple platforms • Supports pre-emptive multitasking & • • multithreading Secure file system (NTFS) Applications have separate address spaces Ø up to 4 Gb of memory Ø up to 16 Eb of disk space (1 Eb = 260 bytes)

NT architecture (continued) • Server products have scope for huge additional functionality… Øoffered as services • Problems: Ømuch of the code in NT 4 was new, and bugs had to be ironed out Øeach server had its own security database which created considerable problems for scalability

Windows 2000 • Further big jump Ø Designed to merge: • peer-peer networking capabilities of Windows • client-server requirements of LANs • Yet could still work with “DOS-based” i. e. Windows 3. x/95/98 clients Ø Microsoft’s own “history of Windows” (clientend/desktop versions): Ø http: //www. microsoft. com/windows/winhistorydeskt op. mspx

Windows 2000 • Added functionality: Ø Scalable • active directory n n X 500 compliant directory service enterprise-wide security & resource-sharing • arguably better than NDS n finished off Novell Netware… Ø Secure • • secure remote authentication Kerberos PKI-ready terminal services n remote log on with minimal computing resources

More Recent OS Developments • Novell survived by: Ø merging with developers of Linux Ø continuing to support “legacy” Netware systems • HP kept VMS customer base… Ø still developing as Open. VMS: • http: //h 71000. www 7. hp. com/openvms/30 th/inde x. html Ø Once DEC alpha chip was history, developed new Intel-based hardware platform (Integrity) to interface with VMS kernel • Linux slowly gaining popularity…

More recent OS developments • Microsoft has continued to improve NT: Ø Server-end • Windows 2003 Server, 64 -bit! • Windows 2008 Server Ø Client end • Vista • Windows 7 Ø And although Bill Gates has now retired, Steve Cutler is still there… VIDEO: • • http: //www. amd. com/usen/assets/content_type/Downloadable. Assets/Microsoft_Video_Stateme nt. wmv Desktop changes: Ø ever smaller Ø mobile devices also have CPUs & operating systems Ø also have user interfaces & use apps…

So, which network operating system would you use today? • • NT, VMS, or a variety of Unix Time to do some research…