1. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction L E C T U R E 1 INTRODUCTION

2. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction SYSTEM System (from Latin systēma, in turn from Greek systēma) is a set of interacting or interdependent entities forming an integrated whole. Most systems share common characteristics, including: –Systems have structure, defined by parts and their composition; –Systems have behavior, which involves inputs, processing and outputs of material, energy or information; –Systems have interconnectivity: the various parts of a system have functional as well as structural relationships between each other.

3. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction SYSTEM What is System? –A group of interdependent items that interact regularly to perform a task. –An established or organized procedure; a method. –A computer system refers to the hardware and software components that run a computer or computers. –An information system is a system that collects and stores data. –System often simply refers to the operating system

4. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction System Administrator A system administrator, systems administrator, or sysadmin, is a person employed to maintain and operate a computer system and/or network. System administrators may be members of an information technology department. The duties of a system administrator are wide-ranging, and vary widely from one organization to another.

5. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Sysadmins are usually charged with –installing, –supporting, and –maintaining servers or –other computer systems, and planning for and responding to service outages and other problems.

6. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Other duties may include –scripting or light programming, –project management for systems-related projects, supervising or training computer operators, and –being the consultant for computer problems beyond the knowledge of technical support staff. A system administrator must demonstrate a blend of technical skills and responsibility in order to perform their job well.

7. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Duties of a System Administrator Analyzing system logs and identifying potential issues with computer systems. Introducing and integrating new technologies into existing data center environments. Performing routine audits of systems and software. Performing backups. Applying operating system updates, patches, and configuration changes. Installing and configuring new hardware and software.

8. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Adding, removing, or updating user account information, resetting passwords, etc. Answering technical queries. Responsibility for security. Responsibility for documenting the configuration of the system. Troubleshooting any reported problems. System performance tuning. Ensuring that the network infrastructure is up and running.

9. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Client – Server Model The term client-server refers to a popular model for computer networking that utilizes client and server devices each designed for specific purposes. –The client-server model can be used on the Internet as well as local area networks (LANs). –Examples of client-server systems on the Internet include Web browsers and Web servers, FTP clients and servers, and DNS.

10. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Client-server computing or networking is a distributed application architecture that partitions tasks or work loads between service providers (servers) and service requesters, called clients. Often clients and servers operate over a computer network on separate hardware.

11. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction A server machine is a high-performance host that is running one or more server programs which share its resources with clients. A client does not share any of its resources, but requests a server's content or service function. –Clients therefore initiate communication sessions with servers which await (listen to) incoming requests.

12. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Client and Server Devices –Client/server networking grew in popularity many years ago as personal computers (PCs) became the common alternative to older mainframe computers. –Client devices are typically PCs with network software applications installed that request and receive information over the network. –Mobile devices as well as desktop computers can both function as clients.

13. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction –A server device typically stores files and databases including more complex applications like Web sites. –Server devices often feature higher-powered central processors, more memory, and larger disk drives than clients.

14. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Server Operating Systems Server OSes are designed from the ground up to provide platforms for multi-user, frequently business- critical, networked applications. As such, the focus of such operating systems tends to be security, stability and collaboration, rather than user interface. Server OSes provide a platform for multi-user applications, and most come bundled with a batch of common server applications, such as Web servers, e- mail agents and terminal services.

15. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Common applications for server OSes –File and printer sharing –Application services (including databases) –Web site services –E-mail, groupware and messaging –Caching

16. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Do I need a different server for each application? –Sometimes - a typical server OS can handle two of more of these tasks for a small number of clients. –When a large number of clients are added, or the applications called for use a lot of processing power, you may need to add more servers and diversify their functions. –Load monitoring (that is, reporting on the amount of work the server and network is doing) in server OSes can give a good indication of when a new server - or an upgraded server - might be necessary.

17. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Things to look for in a server OS –Administration - what tools are available and how easy are they to use. –Security - perhaps the most important feature, and the hardest to judge and get right. In general, the more tasks a server performs, the more potential holes hackers have to get in. –Stability - downtime is an organizational killer. –Features - does it have the specific services you want built in (does it have an HTTP server for your planned Intranet, for instance, or an FTP server for remote file access)?

18. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction –Performance - is the server OS, and the hardware platform it runs on, fast enough for your needs? –Hardware requirements - whether the server OS can run on Intel or AMD hardware, or whether it requires a proprietary platform, for example Sun's Solaris operating system runs only on Sun hardware. –Scalability - how many clients can reasonably access this system, and how far can the OS scale in the future (to new hardware or more processors, for instance) if needed. –TCO - how much the additional costs of the operating system are in terms of productivity, administration and downtime. –Third-party applications - what products are available for the platforms that aren't covered by the basic set included in the OS.

19. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Server Operating Systems Operating SystemCompanyHardware PlatformNo. of processorsAppropriate for: Windows 2000 Server/Advanced Server/Datacentre MicrosoftIntel/AMD 4 (Server) 8 (Advanced) 32 (Datacentre) Small, medium and large servers Windows Server 2003 R2 Standard/Enterprise/ Datacentre/Web Server/Small Business Microsoft Intel/AMD & IA-64, Opteron for 64-bit versions of Windows Server 2003 4 (Standard) Up to 8 (Enterprise) Minimum 8, Maximum 64 (Datacentre) Small, medium and large servers Linux (Red Hat, Mandrake, Debian, SuSE, etc.) Open SourceMany (esp. Intel/AMD) 32 (Linux is readily used on more than 4 CPUs) Small to large servers FreeBSD 7.0Open Source x86, Alpha, IA-64, PC-98 and UltraSPARC 4Small to large servers Mac OSX Server v10.4 Apple PowerPC with a G3, G4, or G5 processor (Apple) 2 (4 available later) Small to medium servers NetWare 6.5NovellIntel/AMD32Medium to large servers Solaris 10 Sun Microsystems Sparc, Intel x64 or x86128 Medium to enterprise servers HP-UX 11i v1.6 & HP- UX 11i v2 Hewlett-PackardPA-RISC, Intel Itanium64Enterprise servers IRIX 6.5SGIMIPS64Enterprise servers AIX 5L 5.2IBMPowerPC (RS/6000)32Enterprise servers

20. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Workgroup A workgroup is Microsoft's terminology for a peer- to-peer PC computer network. Microsoft operating systems in the same workgroup may allow each other access to their files, printers, or Internet connection. Members of different workgroups on the same local area network and TCP/IP network can only access resources in workgroups to which they are joined. Workgroups can be used only if Microsoft Network is enabled.

21. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Workgroup Computing A workgroup is a collection of individuals working together on a task. Workgroup computing occurs when all the individuals have computers connected to a network that allows them to send e-mail to one another, share data files, and schedule meetings. Sophisticated workgroup systems allow users to define workflows so that data is automatically forwarded to appropriate people at each stage of a process.

22. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Windows Server Domain A Windows Server domain is a logical group of computers running versions of the Microsoft Windows operating system that share a central directory database. This central database (known as Active Directory starting with Windows 2000, also referred to as NT Directory Services on Windows NT Server operating systems, or NTDS) contains the user accounts and security information for the resources in that domain. Each person who uses computers within a domain receives his or her own unique account, or user name. This account can then be assigned access to resources within the domain.

23. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction In a domain, the directory resides on computers that are configured as "domain controllers." A domain controller is a server that manages all security-related aspects between user and domain interactions, centralizing security and administration. A Windows Server domain is normally more suitable for moderately larger businesses and/or organizations.

24. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction A domain does not refer to a single location or specific type of network configuration. The computers in a domain can share physical proximity on a small LAN or they can be located in different parts of the world. As long as they can communicate, their physical position is irrelevant.

25. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction Domain Controller On Windows Server Systems, a domain controller (DC) is a server that responds to security authentication requests (logging in, checking permissions, etc.) within the Windows Server domain. In Windows NT, one domain controller per domain was configured as the Primary Domain Controller (PDC); –all other domain controllers were Backup Domain Controllers (BDC).

26. System Administration Institute of Business & Management Sciences Muhammad Shahzad AliLecture 1: Introduction A BDC could authenticate the users in a domain, but all updates to the domain (new users, changed passwords, group membership, etc) could only be made via the PDC, which would then propagate these changes to all BDCs in the domain. If the PDC was unavailable (or unable to communicate with the user requesting the change), the update would fail. If the PDC was permanently unavailable (e.g. if the machine failed), an existing BDC could be promoted to PDC.