COMP2122 Network Operating Systems Richard Henson University of Worcester November 2010

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

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

First British Operating system Leo 3 was the first mass produced British Computer Leo 3 was the first mass produced British Computer  94 units built full list of buyers computers.org.uk/newleo3s.htmfull list of buyers computers.org.uk/newleo3s.htmhttp:// computers.org.uk/newleo3s.htmhttp:// computers.org.uk/newleo3s.htm  each had a loudspeaker connected to the CPU… so operators could tell if it was “looping”  had a multi-tasking operating system called “master program” some continued in service until 1981 some continued in service until 1981

First Minicomputer & Operating system Produced by Digital Equipment Corporation (DEC) in 1963 Produced by Digital Equipment Corporation (DEC) in 1963  called the PDP-6 “mini” in size compared to mainframes“mini” in size compared to mainframes huge by today's standardshuge by today's standards  operating system called “monitor” evolved into the TOPS10 (1970)evolved into the TOPS10 (1970) ran on the legendary PDP-10ran on the legendary PDP-10 still going until 1988still going until 1988 can get it even now:can get it even now:

Unix Spin-off (1969) from project MULTICS Spin-off (1969) from project MULTICS  First attempt at a multiuser operating system Consortium including Bell Labs, AT&T,Consortium including Bell Labs, AT&T, n US equivalent of BT at that time FAILED! Too ambitious…FAILED! Too ambitious…  Bell Labs: cut down derivation called UNICS -> UNIX written in assembly language by Ken Thompsonwritten in assembly language by Ken Thompson sharing of processes also being explored in The ARPAnet projectsharing of processes also being explored in The ARPAnet project Commercial Challenge:Commercial Challenge: DEC PDP-7 minicomputerDEC PDP-7 minicomputer needed a general purpose “time sharing” operating system for multiuser use…needed a general purpose “time sharing” operating system for multiuser use… their own os “monitor” had not yet matured into TOPS-10their 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 Thompson looking for a high-level language to develop a time sharing os briefly toyed with Fortranbriefly toyed with Fortran worked with colleague Dennis Ritchie to create their own higher level language – “B”, based on BCPLworked with colleague Dennis Ritchie to create their own higher level language – “B”, based on BCPL development of B = newB (NB)development of B = newB (NB) development of NB -> Cdevelopment of NB -> C Unix kernel was rewritten in “C” (1973)Unix kernel was rewritten in “C” (1973)

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

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

Silicon Valley, TCP/IP and Unix University of California created The ARPAnet (1969)University of California created The ARPAnet (1969) 1975 onwards: Berkeley, north of San Francisco1975 onwards: Berkeley, north of San Francisco hub for its own unique brand of Unix developmentshub for its own unique brand of Unix developments start of “Silicon Valley” (IT hot spot around SF)start of “Silicon Valley” (IT hot spot around SF) ARPAnet teamARPAnet team developed TCP/IPdeveloped TCP/IP 1980, gained approval through RFC1980, gained approval through RFC operating system that would support TCP/IP arrived in 1983…operating system that would support TCP/IP arrived in 1983… Berkeley Unix (v4.2) packaged with TCP/IP protocol stackBerkeley Unix (v4.2) packaged with TCP/IP protocol stack Sun microsystems producing the hardware…Sun microsystems producing the hardware…

Bell Labs Unix becomes Commercial… US Dept of Justice broke up AT&T in 1984US Dept of Justice broke up AT&T in 1984 Bell Labs then allowed to sell their Unix source code…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 (!)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 marketSCO Unix for PC became a lucrative business market operating system provided security on a PC where DOS couldn’t…operating system provided security on a PC where DOS couldn’t…

Bad days for Unix… UNIX free by nature from outset UNIX free by nature from outset  not so on an Intel PC, thanks to SCO!!!  Bell Labs jealously guarded the source code…  universities lost interest Unix became expensive to buy… and was still not user-friendly or easy to use so even more expensive to own! 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! From 1992 (Linus Torvalds, University of Helsinki) made free Unix possible again!  LINUX – based on his name… Took… Took…  Stallman’s GNU open source Unix which Tanenbaum had developed into MINIX…which Tanenbaum had developed into MINIX…  very stable  secure file system  very efficient, optimised code  earlier versions ran on an Intel 486! Still Unix, still a server-end system Still Unix, still a server-end system  for client-server networking, need client-end software: e.g. Banyan VINESe.g. Banyan VINES

Linux Still freely available via Internet! Still freely available via Internet! Huge range of software tools for managing UNIX networks available for download Huge range of software tools for managing UNIX networks available for download Problems (compared to Windows): Problems (compared to Windows):  not as easy to manage  limited on-screen help  limited range of good application software  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 SCO sued Linux in 2003 for misappropriation of Unix System V code  subsequently sued: IBMIBM Red Hat (Novell)Red Hat (Novell) Anyone else commercially involved with LinuxAnyone else commercially involved with Linux n e.g DaimlerChrysler US Court finally shut them up in August 2007 by saying SCO had no rights to the code Novell were using… US Court finally shut them up in August 2007 by saying SCO had no rights to the code Novell were using…  Linux continues to be “free” to this day…

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

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

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

Other Features of I/O optimisation: I/O optimisation:  disk caching  elevator seeking (disk accesses ordered according to position on disk)  directory hashing  MHS protocol for message-handling and within the LAN

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

Improvements (version 4) Scalable across servers Scalable across servers  Using Network Directory Service (NDS)  network info stored in a managed naming system as a bindery across the whole network  security includes NDS attributes LANalyser tool for analysing packets & identifying protocol problems LANalyser tool for analysing packets & identifying protocol problems Easier to use than v3: GUI-based Easier to use than v3: GUI-based  supported: 32-bit processing32-bit processing long filenames - like Windows 95 onlong filenames - like Windows 95 on SMP - symmetric multi-processing (2 processors)SMP - symmetric multi-processing (2 processors) Up to 1000 usersUp to 1000 users remote Network mgtremote Network mgt

Enduring Problems with Netware Only ran on Intel Platform Only ran on Intel Platform Reliant on DOS/Windows at the client end Reliant on DOS/Windows at the client end NDS not not X500 compliant NDS not not X500 compliant not directly compatible with Internet protocols such as TCP/IP not directly compatible with Internet protocols such as TCP/IP  based on IPX/SPX protocol (OSI levels 3 and 4) for interprocess communication  used MAC addresses (fixed) as unique identifiers, rather than IP addresses not suitable for peer-peer networking not suitable for peer-peer networking not pre-emptive in handling processes not pre-emptive in handling processes

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

What was DEC? World’s most innovative computer company for many years… World’s most innovative computer company for many years…  first minicomputer: PDP-1 (Programmable Data Processor)PDP-1 (Programmable Data Processor)  first UNIX/C implementation On PDP-5On PDP-5  most successful minicomputer: VAX (Virtual Addresss eXtension)VAX (Virtual Addresss eXtension)  first virtual memory operating system VMS (virtual memory system) for VAXVMS (virtual memory system) for VAX  first commercially successful RISC chip alphaalpha  first commercial Internet domain & website  first successful search engine: AltaVista

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

What went wrong with DEC? Now long enough ago to be of historical interest… Now long enough ago to be of historical interest…  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…DEC keen to get their alpha chip onto the original Windows NT… signed away any rights to the code used in creating windows NTsigned away any rights to the code used in creating windows NT so Microsoft effectively got the technologies behind VMS for free!!!!so Microsoft effectively got the technologies behind VMS for free!!!! But thanks to HP, and enthusiastic users, VMS lives But thanks to HP, and enthusiastic users, VMS lives  available for download at:

Microsoft & Operating Systems Original IBM PC operating system… Original IBM PC operating system…  whilst the US government was being defeated in the courts by IBM…  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):story about IBM negotiations with Bill Gates (regarding his mate Tim Paterson’s os): n and the tragedy of Gary Kildall (creator of CP/M)…and the tragedy of Gary Kildall (creator of CP/M)… n _mz063.htm _mz063.htm _mz063.htm

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

OS2, Windows, and Windows NT By late 1980s, PCs being used for serious business purposes By late 1980s, PCs being used for serious business purposes  IBM needed a serious operating system for the PC…  Microsoft worked them on OS2  still didn’t see Gates as a rival! At about the same time… At about the same time…  Cutler left DEC… joined Microsoft  scope for a virtual memory operating system… (Windows)(Windows)

Windows On the one hand On the one hand  Microsoft were working with IBM on OS2 One the other hand: One the other hand:  they were working on developing Windows and working with software developers to provide applications for Windows…and working with software developers to provide applications for Windows… n users want apps, not operating systems! Guess which one won??? Guess which one won???  you’ve got it… Microsoft now bigger than IBM

Windows NT Windows was based on DOS Windows was based on DOS  virtual memory enabled multitasking  but fundamentally flawed… Intermediate towards a new “serious” operating system… Intermediate towards a new “serious” operating system… using DEC technology…using DEC technology… “New Technology” operating system quietly released in 1993 “New Technology” operating system quietly released in 1993  as a disguised front end enhancement to Windows 3.1 i.e. Windows 3.11 (for workgroups)i.e. Windows 3.11 (for workgroups)

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

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

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

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

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

The 32-bit Windows NT architecture Secure kernel based on VMS Secure kernel based on VMS  available for multiple platforms Supports pre-emptive multitasking & multithreading Supports pre-emptive multitasking & multithreading Secure file system (NTFS) Secure file system (NTFS) Applications have separate address spaces Applications have separate address spaces  up to 4 Gb of memory  up to 16 Eb of disk space (1Eb = 2 60 bytes)

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

Windows 2000 Further big jump Further big jump  Designed to merge: peer-peer networking capabilities of Windowspeer-peer networking capabilities of Windows client-server requirements of LANsclient-server requirements of LANs Yet could still work with “DOS-based” i.e. Windows 3.x/95/98 clients Yet could still work with “DOS-based” i.e. Windows 3.x/95/98 clients  Microsoft’s own “history of Windows” (client- end/desktop versions):  op.mspx op.mspx op.mspx

Windows 2000 Added functionality: Added functionality:  Scalable active directoryactive directory n X500 compliant directory service n enterprise-wide security & resource-sharing arguably better than NDSarguably better than NDS n finished off Novell Netware…  Secure secure remote authenticationsecure remote authentication KerberosKerberos PKI-readyPKI-ready terminal servicesterminal services n remote log on with minimal computing resources

More Recent OS Developments Novell survived by: Novell survived by:  merging with developers of Linux  continuing to support “legacy” Netware systems HP kept VMS customer base… HP kept VMS customer base…  still developing as OpenVMS: dex.htmlhttp://h71000.www7.hp.com/openvms/30th/in dex.htmlhttp://h71000.www7.hp.com/openvms/30th/in dex.htmlhttp://h71000.www7.hp.com/openvms/30th/in dex.html  Once DEC alpha chip was history, developed new Intel-based hardware platform (Integrity) to interface with VMS kernel Linux slowly gaining popularity… Linux slowly gaining popularity…

More recent OS developments Microsoft has continued to improve NT: Microsoft has continued to improve NT:  Server-end Windows 2003 Server, 64-bit!Windows 2003 Server, 64-bit! Windows 2008 ServerWindows 2008 Server  Client end VistaVista Windows 7Windows 7  And although Bill Gates has now retired, Steve Cutler is still there… VIDEO: en/assets/content_type/DownloadableAssets/Microsoft_Video_Stateme nt.wmvhttp:// en/assets/content_type/DownloadableAssets/Microsoft_Video_Stateme nt.wmvhttp:// en/assets/content_type/DownloadableAssets/Microsoft_Video_Stateme nt.wmvhttp:// en/assets/content_type/DownloadableAssets/Microsoft_Video_Stateme nt.wmv Desktop changes: Desktop changes:  ever smaller  mobile devices also have CPUs & operating systems  also have user interfaces & use apps…

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