Disadvantages in the File System

·         Data Redundancy

·         Data Inconsistency

·         Difficulty in Accessing Data

·         Data Isolation

·         Integrity Problems

·         Atomicity Problem

·         Concurrent Access anomalies

·         Security Problems

Data Redundancy
Data Redundancy is same information’s are duplicated in several files. This makes data redundancy.
Data Inconsistency
Data Inconsistency means different copies of the same data are not matching. This  occurs as the result of  update operations that are not updating the same data stored at different places.

Example: Address Information of a customer is recorded differently in  different files.

Difficulty in Accessing Data
It is not easy to retrieve information using a conventional file processing system. Convenient and efficient information retrieval is almost impossible using conventional file processing system. 
Data Isolation
Data are scattered in various files, and the files may be in different format, writing new application program to retrieve data is difficult.

Integrity Problems
The data values may need to satisfy some integrity constraints.

 For example  the balance field Value must be greater than 5000. We have to handle this through program code in file processing systems. But in database we can declare the integrity constraints along with definition itself.

Purpose and functions of Database Management Systems

·         Data redundancy is found- the presence of duplicate data in multiple data files

e.g. Customer Name, NI number, Address is present in several different files on several different systems. Errors are generated, time entering data is wasted.

·         Data inconsistency will become a problem

 e.g. information is duplicated in each system and may be updated in most systems but not necessarily in all – the savings account and loan account may have different addresses for a particular customer.

·         Lack of data independence.

In the bank imagine cases where any change in data format or structure requires a change in all the programs that access the data.

e.g. effort required to change from 3-digit STD to 4-digit STD may be very difficult.

·         Data lacks integrity

This is the quality by which information from the system can be trusted.

·         Lack of flexibility

Creating reports

e.g. in this system a summary of account balances in each separate account would require separate reports for each open account or cutting and pasting into a word processor file – not a satisfactory state of affairs.

·          Data not shareable. Similarly if different departments want to access data this would be very awkward.

operating system

1. Explain the various types of computer systems. 
Mainframe systems
Desktop systems
Multiprocessor systems
Distributed systems
Clustered systems
Real-time systems
Handheld systems
2. Explain how protection is provided for the hardware resources by the operating system. 
Dual mode operation
I/O protection with diagram
Memory protection with diagram
CPU protection
3. What are the system components of an operating system and explain them? 
Process management
Main-memory management
File management
I/O management
Secondary storage management
Networking
Protection system
Command-interpreter system
4. Write about the various system calls. 
Process control
File management
Device management
Information maintenance
Communication
5. What are the various process scheduling concepts 
Scheduling queues with diagram
Queueing diagram
Schedulers

Context switch with diagram
6. Explain about interprocess communication. 
Message-passing system
Naming
Direct communication
Indirect communication
Synchronization
Buffering
7. Give an overview about threads. 
Thread definition
Motivation
Diagram
Benefits
User and kernel threads
8. Explain in detail about the threading issues. 
The fork and exec system calls
Cancellation
Signal handling
Threads pools
Thread-specific data
9. Write about the various CPU scheduling algorithms. 
First-come, first-served scheduling
Shortest-job-first scheduling
Priority Scheduling
Round-robin scheduling
Multilevel queue scheduling
Multilevel feedback queue scheduling
10.Write notes about multiple-processor scheduling and real-time scheduling. 
Homogeneous systems
Load sharing
Self-scheduling
Resource reservation
Priority inversion
Priority inheritance protocol
Dispatch latency with diagram
11.What is critical section problem and explain two process solutions and multiple process solutions? 
Critical section problem definition
Two process solutions
Algorithm 1, 2 & 3
Multiple-process solution with algorithm
12.Explain what semaphores are, their usage, implementation given to avoid busy waiting and binary semaphores.
Semaphore definition
Usage for mutual exclusion and process synchronization
Implementation to avoid spinlock using block and wakeup
Binary semaphores
13.Explain the classic problems of synchronization. 
The bounded-buffer problem with structure
The readers-writers problem with structure
The dining-philosophers problem with structure
14.Write about critical regions and monitors. 
Critical region definition
Implementation of the conditional-region construct
Monitor definition
Syntax of monitor
Schematic view of monitors
Monitor with condition variables
Monitor solution to dining-philosopher problem
15.Give a detailed description about deadlocks and its characterization 
Deadlock definition
Deadlock conditions
Mutual exclusion
Hold and wait
No pre-emption
Circular wait
Resource allocation graph
16.Explain about the methods used to prevent deadlocks 
Ensure that at least one of the following does not hold
Mutual exclusion
Hold and wait
No pre-emption
Circular wait
17.Write in detail about deadlock avoidance. 
Safe state and safe sequence
Diagram for safe, unsafe & deadlock states
Resource-allocation graph algorithm
18.Explain the Banker's algorithm for deadlock avoidance. 
Deadlock avoidance definition
Data structures used

Safety algorithm
Resource request algorithm
19.Give an account about deadlock detection. 
Single instance of each resource type
Wait-for graph
Several instances of a resource type
Detection-algorithm usage
20.What are the methods involved in recovery from deadlocks? 
Process termination
Resource pre-emption
21.Explain about contiguous memory allocation. 
Contiguous allocation
Memory protection with diagram
Memory allocation
First fit
Best fit
Worst fit
Fragmentation
22.Give the basic concepts about paging. 
Paging definition
Basic method-page, frame, page table, page number & page offset
Paging hardware diagram
TLB with diagram
Protection-protection bits & valid-invalid bits