Functions of an Os Platform
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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