This document discusses several topics related to distributed operating systems including: 1. What a distributed system is and examples like clusters, grids, clouds, and supercomputers. 2. Multiprocessor operating systems and how they allow multiple CPUs to share memory. 3. Databases and why they are needed over traditional file management. Database components and architecture are also covered. 4. Operating system structure including monolithic vs layered approaches and examples like Windows NT with its kernel, executive services, and system services layers. 5. Key design issues for distributed systems like transparency, reliability, performance, scalability, naming, replication, synchronization, and security.

1. SK MOHAMED KASIM
Operating system

2. Given topic
 DISTRIBUTED OS
 Multiprocessor OS
 Database
 STRUCTURE
 DESIGN ISSUE

3. What is a Distributed System?

4. “A collection of independent
computers that appears to its users as
a single coherent system”

5. Distributed Systems
A distributed system organized as middleware. The middleware layer extends over
multiple machines, and offer each application the same interface.

6. Distributed Systems

7. Distributed Systems
Clusters, Grids, Clouds, and Supercomputers

8. Cluster Computing

9. Supercomputing
Highly-tuned computer clusters using commodity
processors combined with customized network
interconnects and customized operating system

10. Grid Computing

11. MULTI-PROCESSOR OS

12. Multiprocessors
Definition:
A computer system in which two or more
CPUs share full access to a common RAM

13. Multiprocessor Systems
 Continuous need for faster computers
 shared memory model
 message passing multiprocessor
 wide area distributed system

14. Distributed Systems (1)
Comparison of three kinds of multiple CPU systems

15. DATABASE

16.  File Management vs Database Management (why do we need
database?)
 Advantages of Database systems: storage persistence,
programming interface, transaction management
 Data Model (What is Data?)
 Database Language (How to manipulate data?)
 DBMS Architecture and Database System Components (How can
you build a billion-dollar software, like Oracle? Or you can get it
free, mySQL?)
 Users classification (What you can do and what you cannot do?)

17. Where are databases?
 You cannot avoid it and it’s everywhere!
 You can say it actually makes the current society and your life work!
 Banking/Credit card /Social Security Info…
 Online shopping/booking…

18. STRUCTURE

19. OS Structure
 monolithic approach
 the whole OS is one large program
 often used under resource constraints (processing power, memory space)
 example: PC DOS
 layered approach
 functionalities are grouped into layers from hardware to user programs
 better separation of functions
 example: OS

20. Kernel
 core part of the operating system comprising the minimal set of functionalities
 process dispatching
 basic memory management
 interprocess communication
 protection
 is always kept in main memory
 porting is made easier

21. OS Structure Examples
 MS-DOS & Windows
 Windows NT
 Unix

22. MS-DOS & Windows Structure
 originally (DOS 1) monolithic due to space and processing power restrictions (Intel
8086, 8 KBytes main memory)
 slow incorporation of advanced concepts
 hard disk, hierarchical file systems, I/O redirection, background printing, networking, ...
 fresh start with Windows NT
 single-user, multitasking
 designed for 32-bit microprocessors (Intel Pentium)

23. Windows NT Structure
 hardware abstraction layer (HAL)
 provides adaptation to the underlying hardware through a generic hardware interface
 microkernel
 thread scheduling, process switching, exception handling (interrupts), multiprocessor
synchronization
 executive services
 modules for system functions
 I/O manager, object manager, process manager, virtual memory manager, security reference
monitor, windows modules
 system services
 interface to software running in user mode

24. Windows NT StructureMicrokernel OS
Users and
User Programs
[Stallings 98]
Hardware
Micro-Kernel
System Services
WindowsNT
Executive
Applicationsand
UserInterface
Hardware Abstraction Layer (HAL)
I/O
Manager
Object
Manager
Security
Reference
Monitor
Process
Manager
Local
Procedure
Call
Facility
Virtual
Memory
Manager
Window
Manager
Graphic
Device
Drivers
Device
Drivers
Network
Drivers
File System
Drivers
POSIX
Subsystem
Win32
Subsystem
OS/2
Subsystem
Security
Subsystem
Cache
Manager

25. DESIGN ISSUE
 The distributed information system is defined as “a number of interdependent
computers linked by a network for sharing information among them”. A distributed
information system consists of multiple autonomous computers that communicate
or exchange information through a computer network.

26. Design issues of distributed system
 Transparency
 flexibility
 reliability
 performance
 Scalability
 Naming
 replication
 synchronization
 security

27. Structure issue