Functions of an Os Platform

Functions of an Operating System

Operating Systems is a computer program that controls the operation of the hardware of a computer and the execution of programs. The primary functions of an operating system include:

1) Managing and controlling the hardware of the computer, e.g., drivers

2) Interfacing between hardware and software, i.e. how programs and applications use hardware - keyboard, mouse, monitor.

3) Managing memory, i.e., multitasking, multiprocessing and threads

4) Managing and executing applications

5) Diagnosing problems with software and hardware

6) Managing Storage Devices and Files, e.g., NTFS and Netware file system

7) Providing a User Interface

Additional Functions of a Network Operating System

Where multiple hosts share the workload and resources, but each host executes its own programs

1) Connecting to the Network, e.g., network interface card drivers, communication protocols, and client services.

2) Enabling remote users to access and share resources, and user interfaces to use various share services, e.g., utilities, web access, SMTP.

3) Provide additional security to access shared resources, i.e., authorization (logon) and authorization (resources) services.

4) Provide applications for network use, e.g., Web, SMTP, and DHCP servers.

5) Provide network diagnostics utilities.

Types of Network Operating Systems

Peer-to-Peer or Workgroup Model

Any computer can be a server or a client, or both. Examples of these NOS include Microsoft Networking and Windows 2k Member servers The security system is decentralized, and is stored in the local registry. Practical for networks up 5 to 10 computers with limited sharing and low security requirements. Every server maintains its own security system. this means that you must have a password on each server.

Peer-to-Peer or Workgroups

Advantages

Disadvantages

Easy-to-share resources

No centralized control over resources

Resources are distributed across all computers

No centralized account management

Little administrative overhead

No centralized administration

Simple to design

No centralized security system

Easy to implement

Inefficient for more than 20 computers

Convienent for small groups in close proximity

Security must be configured manually

Less expensive or free software, does not require a centralized server

Increased training to educate users to use their computer as both a client and a server.

Domain (Client/Server) Model

The designation of one computer to centralize the administration of shared resources and security. It is generally recommended that a computer would be only used as either as a client or a server, but not both. For example, share files will be stored on the server. Windows NT/2K domain controllers, Active directory and Netware are examples of the client Server model.

Client/Server or Domain Model

Advantages

Disadvantages

Centralized resource sharing

Significant administrative effort and overhead

Centralized resource control

Complicated designs; requires advanced planning

Centralized account management

Requires one or more powerful, expensive servers (especially for Win NT/2K)

Centralized security management

Absolute security is hard to achieve when the security system is so powerful and still managed by people

Efficient for virtually unlimited number of workstations

Expensive for domain controllers and NDS replica servers, and access lags increase network traffic

Users need only be trained for clients

Some increased level of knowledge is required by network administrators

Can be used to connect to remote networks or clients

Larger scope requires more documentation and training

May be able to connect to a variety of client operating systems and versions.

Licensing fees may be costly. Perhaps that is why Linux is growing in popularity

May lower the Total Cost of Ownership (TCO), e.g., Distributing applications and upgrades, remote desktop control, and inventory features, etc. (Z.E.N.)

There are two types of Domain or Client Server models:

Single Domain or Single Server Model

In previous years

Directory Services or Multiple Server Model

Feature

Netware 3.x

Netware 4.x

Netware 5.x

Netware 6.x

Win NT Server

Win 2k Server

Linux

Single Processors Performance

E,