File Concepts and Student Marks

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is a directory structure primarily used for?

To increase the speed of file creation

To organize many files in the file system (correct)

To encrypt files for security

To improve file duplication

Which operation allows you to remove a file from the directory?

Search for a file

Delete a file (correct)

Rename a file

List a directory

What is a drawback of a single-level directory structure?

It is too complex for users

It requires too much storage space

It allows easy file retrieval

File name conflicts can occur (correct)

In a two-level directory system, what is the role of the root directory?

It acts as the first-level directory Signup and view all the answers

How does a tree-structured directory solve the issues present in two-level directories?

By creating subdirectories to manage large numbers of files Signup and view all the answers

Which operation allows you to change the name of a file within a directory?

Rename a file Signup and view all the answers

What is a major advantage of a two-level directory system compared to a single-level directory?

Elimination of file name conflicts among users Signup and view all the answers

Which of the following best describes the purpose of traversing the file system?

To access every directory and file within the structure Signup and view all the answers

What happens to the read pointer after a read operation is completed?

It is updated to the next read location. Signup and view all the answers

Which operation is referred to as 'file seek'?

Repositioning the current file position pointer. Signup and view all the answers

When truncating a file, what remains after the operation?

The file attributes. Signup and view all the answers

What file extension is commonly associated with executable files?

.exe Signup and view all the answers

What does the operating system require to load an executable file?

A defined internal file structure. Signup and view all the answers

In UNIX OS, how are all files defined?

As streams of bytes. Signup and view all the answers

What is the logical record size of files in UNIX?

1 byte. Signup and view all the answers

What is one consequence of an OS supporting multiple file structures?

It increases the size of the OS. Signup and view all the answers

What does a free block contain in a linked free space list?

Pointer to the next free block Signup and view all the answers

What is the main advantage of the grouping approach in linked free space lists?

It allows easy access to multiple free blocks at once. Signup and view all the answers

What is a significant drawback of the linear list implementation in directory management?

Searching for unique file names can be time-consuming. Signup and view all the answers

How does the hash table enhance the directory management process compared to a linear list?

By allowing random access to directory entries. Signup and view all the answers

In the counting approach of free space management, what information is stored in the entries?

Address of the first free block and the count of following free blocks Signup and view all the answers

What must happen when a new file is created in a linear list directory implementation?

The entire list is checked for unique file names. Signup and view all the answers

What role does the hash function play in directory management using hash tables?

To generate keys for efficient searching. Signup and view all the answers

What happens during the process of file deletion in a linear list directory?

The whole list needs to be traversed. Signup and view all the answers

What characterizes synchronous I/O operations?

CPU execution halts while I/O operations are performed. Signup and view all the answers

Which I/O communication method allows for data transfer without CPU intervention after setup?

Direct Memory Access (DMA) Signup and view all the answers

In memory-mapped I/O, which of the following is true?

Memory addresses are used both by memory and I/O devices. Signup and view all the answers

What is the main benefit of using Direct Memory Access (DMA) with fast devices?

It minimizes the CPU's time spent handling interrupts. Signup and view all the answers

Which of the following best describes Special Instruction I/O?

It utilizes specific CPU instructions tailored for I/O control. Signup and view all the answers

What information does the file control block (FCB) contain?

File ownership, permissions, and location of file contents Signup and view all the answers

What is typically a limitation of memory-mapped I/O?

It relies heavily on CPU involvement for data transfer. Signup and view all the answers

Which statement accurately reflects how DMA operates?

DMA requires CPU intervention only during the transfer. Signup and view all the answers

What does the Boot Control Block do?

Contains information needed to boot an OS from a specific volume Signup and view all the answers

When a file is opened, what does the open() call do first?

Searches the system-wide open file table for the file Signup and view all the answers

Which of the following is NOT an approach to communicate with the CPU and I/O devices?

Control Port I/O Signup and view all the answers

What happens when a process closes a file?

The per-process table entry is removed and the open count is decremented Signup and view all the answers

Which of the following accurately describes the Volume Control Block?

It provides details about the number of blocks and free block count for a volume Signup and view all the answers

What information is copied into the system-wide open file table during the open process?

An existing FCB and tracking details for the open file Signup and view all the answers

What is an essential function of the directory structure in a file system?

To provide a mechanism for organizing files within the system Signup and view all the answers

What occurs after all processes that opened a file close it?

Metadata is updated and FCB entry is removed from the system-wide open file table Signup and view all the answers

What is the primary role of the DMA controller during a data transfer process?

To transfer bytes to the buffer continuously until a counter reaches zero Signup and view all the answers

Which layer of I/O software provides a direct interface for user programs?

User Level Libraries Signup and view all the answers

What characterizes device-independent I/O software?

It enables programs to interact with multiple devices without modification Signup and view all the answers

What is a primary responsibility of device drivers within an operating system?

To encapsulate device-specific code and provide a standard interface Signup and view all the answers

When a DMA transfer is complete, what action does the DMA controller take?

It interrupts the CPU to signal the completion Signup and view all the answers

Which statement about device drivers is accurate?

They handle communication between device-independent software and device controllers Signup and view all the answers

What happens to counter C during a DMA transfer?

It decreases with each byte transferred until it reaches zero Signup and view all the answers

Which of the following is NOT a task performed by device drivers?

Initiate CPU scheduling for concurrent processes Signup and view all the answers

Study Notes

File Concept

Computers store information on various media (magnetic disks, tapes, optical disks).
The operating system converts physical storage into logical storage units called files.
A file is a collection of similar records.
A record is a collection of related fields.
A field holds a single data value.
A database is a collection of related data.

Student Marks

Example data: KUMA (marks 85, 86, Pass), LAKSH (marks 93, 92, Pass)
Each row of data represents a record (e.g., LAKSH, 93, 92, P).
A collection of such records is a data file.

File Attributes

Name: A descriptive name for the file (e.g., report.txt).
Identifier: A unique tag used to identify files in the file system.
Type: Based on file extension (.exe, .obj, .src for executable, object, and source files respectively).
Location: Pointer to a device and the file location on it.
Size: File size in bytes, words or blocks.
Protection: Access control information (read, write, execute).
Time, Date, User ID: Created, last modified and last accessed information, and user details.

File Operations

Creating: Two steps - verify space availability and make an entry for the new file in the directory.
Writing: Requires file name and data to be written. The system locates the file and uses a write pointer to position data.
Reading: Locates the file in the directory and uses a read pointer to read data, updating it after each read.
Repositioning: Moving the file position pointer to a specific value (file seek).
Deleting: Locating the file, releasing file space and erasing the directory entry.
Truncating: Removing the file's contents without changing attributes.

File Types and Extensions

File types are determined by their extensions (e.g., .exe, .txt, .pdf).
Extensions determine the purpose of the file.

File Structure

Files are structured as a series of blocks.
File sizes and structure are determined by operating system.

File Access Methods

Sequential Access: Processing records sequentially (one after the other), often used with magnetic tapes.
Direct (or Relative) Access: Random access to any record without any specific order (used for disk-based files).
Indexed Sequential Access: Files are organized in a sequence based on a key field, making accessing faster (often used in combination with indexes).

Directory Structure

Method of organizing files in the file system, grouping files to make them easier to manage.
Single-level directory: One directory for all files.
Two-level directory: Separate directories for each user, avoiding file naming collisions.
Tree-structured directory: Directories organized in a hierarchical tree structure (subdirectories and sub-subdirectories).
Acyclic graph directory: Shared directories used in collaborative projects.

File System Structure

Disk is the primary storage for files.
Key characteristics enable efficient storage: rewriting in place and direct access to blocks.

Internal File Structure

UNIX defines files as byte streams with each byte addressable by offset.
Blocks: Physical file blocks contain multiple logical records or bytes
Internal fragmentation: wasted space in a block due to difference between physical and logical file sizes
File access and storage methods are defined by the OS.

I/O Control

The I/O subsystem acts as an interface for device drivers to communicate with memory and disk devices.
Device drivers implement specific interactions with I/O devices, enabling data transfer to/from storage.

Synchronous/Asynchronous I/O

Synchronous I/O stops CPU execution while waiting for I/O operations.
Asynchronous I/O performs I/O operations concurrently with CPU execution.

Communication with I/O Devices

CPU communicates with I/O devices through various methods.
I/O special instructions, memory mapped I/O and DMA are part of the methods to communicate.

Device Controllers

Interfaces between devices and the I/O subsystem.
Handle complex communication with I/O devices efficiently.

Allocation Methods

Contiguous: Stores files in a continuous set of blocks, potentially leading to fragmentation (external).
Linked: Files stored as a linked list of blocks.
Indexed: Files with an index block holding pointers to data blocks.

Free Space Management

File system manages free space efficiently using various techniques.
Linked free lists and bitmaps are methods.

Directory Implementation

Linear List: File directory implemented as a singly linked list.
Hash table: More efficient implementation of directories.

Efficiency and Performance

Disk allocation and directory algorithms impact performance.
Disk cache and read/write techniques improve performance.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the concepts of files in computer systems, focusing on how data is organized and represented. You'll learn about file attributes, data records, and how information is stored in files. Brush up on your knowledge of file systems and database records with this engaging quiz.