Operations Systems C8

Question 1

1. Question: What are the main responsibilities of the file management system software?

Answer 1

Answer: The main responsibilities include creating, deleting, modifying, and controlling files.

Question 2

Question: What are the four tasks typically performed by the File Manager?

Answer 2

The four tasks are:
- File storage tracking
- Policy implementation
- File allocation if user access is cleared
- File deallocation

Question 3

How does the file management system efficiently use available storage space?

Answer 3

:** It determines where and how files are stored and communicates file availability.

Question 4

What aspects of file management does policy determine?

Answer 4

Policy determines file storage location and system and user access.

Question 5

What are the two factors influencing access to material in a file management system?

Answer 5

Factor 1 involves flexibility of access to information, including sharing files, providing distributed access, and allowing users to browse public directories.
Factor 2 relates to subsequent protection, such as preventing system malfunctions and implementing security checks like account numbers and passwords.

Factor 1 involves flexible access to information through file sharing, distributed access, and browsing public directories.

Factor 2 relates to protection measures like preventing system malfunctions and implementing security checks such as account numbers and passwords.

Question 6

Define the terms: Field, Record, File, Flat file, Database.

Answer 6

• Field: A group of related bytes identified by user-defined attributes like name, type, and size.
  
  • Record: A group of related fields.
  • File: A group of related records used by specific application programs.
  • Flat file: A file with no connections to other files and no dimensionality.
  • Database: A group of related files interconnected at various levels, providing users flexibility of access to stored data.

Question 7

What are the most common user commands when interacting with the File Manager?

Answer 7

The most common user commands include OPEN, DELETE, RENAME, and COPY.

Question 8

What is a typical volume configuration in a file management system?

Answer 8

A volume typically represents a secondary storage unit, either removable or nonremovable. It may contain multi-file volumes with many files or multi-volume files spread across several volumes. Volume names are managed by the file manager and are easily accessible.

Question 9

What is the purpose of the Master File Directory (MFD)?

Answer 9

The MFD, stored immediately after the volume descriptor, lists the names and characteristics of every file in the volume, including file names, types (such as program files, data files, system files), and subdirectories if supported by the file manager.

The purpose of the Master File Directory (MFD) is to list the names and characteristics of every file in the volume, including file names, types, and subdirectories, providing a comprehensive index immediately after the volume descriptor.

Question 10

What are the disadvantages of having a single directory per volume, as supported by early operating systems?

Answer 10

The disadvantages include long search times for individual files, directory space filling up before disk storage space is fully utilized, inability to create subdirectories or safeguard files, and the need for each program to have a unique name, even for those serving many users.

The disadvantages include

long search times for individual files,

directory space filling up before disk storage is fully used,

inability to create subdirectories or safeguard files,

need for unique names for each program, even those used by many users.

Question 11

How do file managers typically organize file entries for each volume?

Answer 11

File managers create a Master File Directory (MFD) for each volume, which contains entries for both files and subdirectories.

Question 12

What unique properties do subdirectories have in file management systems?

Answer 12

Subdirectories are created upon account opening, treated as files, and flagged as subdirectories in the MFD.

Question 13

How have file managers evolved in terms of subdirectory management?

Answer 13

Modern file managers allow users to create their own subdirectories (folders) to group related files together. This is implemented as an upside-down tree structure.

Question 14

What are the benefits of allowing users to create their own subdirectories?

Answer 14

Allowing users to create subdirectories enables related files to be grouped together, leading to more efficient system searching of individual directories.

Question 15

Describe the components of a file descriptor.

Answer 15

A file descriptor typically includes:
- Filename (each must be unique)
- File type (organization and usage)
- File size
- File location (identifies first physical block or all blocks)
- Date and time of creation
- Owner
- Protection information (access restrictions)
- Record size (fixed size, maximum size)

Question 16

Explain the file-naming conventions mentioned in the provided information.

Answer 16

File-naming conventions include:
- Relative filename: Name without path information, varies in length and appears in directory listings.
- Extension: Appended to the relative filename, typically two to four characters, and identifies the file type or contents.

Question 17

What considerations are involved in selecting a file organization scheme?

Answer 17

File organization scheme selection considerations include data volatility, file activity, file size, and response time requirements.

Question 18

What are the advantages and disadvantages of sequential record organization?

Answer 18

• Advantages: Sequential record organization is easy to implement and offers optimized features.
  
  • Disadvantages: It complicates maintenance algorithms and may require preserving the original order when records are added or deleted.

Question 19

What is the purpose of indexed sequential record organization?

Answer 19

Indexed sequential record organization combines the benefits of sequential and direct access methods, providing efficient record retrieval without collisions. It uses software like Indexed Sequential Access Method (ISAM) to generate index files for record retrieval.

The purpose of indexed sequential record organization is to combine the benefits of sequential and direct access methods, enabling efficient record retrieval without collisions by using software like Indexed Sequential Access Method (ISAM) to generate index files.

Question 20

Explain the advantages and disadvantages of indexed sequential record organization.

Answer 20

• Advantages: It offers efficient record access without collisions, and each entry in the index file contains the highest record key and physical data block location.
  
  • Disadvantages: Overflow areas may be required, complicating the management of large datasets.

Question 21

How is the current byte address (CBA) calculated for fixed-length records in direct access?

Answer 21

For fixed-length records, the current byte address (CBA) is calculated using the formula: CBA = (RN – 1) * RL, where RN is the desired record number and RL is the record length.

Question 22

Why is accessing variable-length records directly virtually impossible in direct access?

Answer 22

Accessing variable-length records directly is virtually impossible because the address of the desired record cannot be easily computed. It requires a sequential search through records or keeping a table of record numbers and corresponding CBAs.

Question 23

Describe the ranked/hierarchical structure implemented in a file management system.

Answer 23

The hierarchical/ranked structure involves structured and modular programming techniques, where the highest module passes information to lower modules. Modules are further subdivided to perform more specific tasks, utilizing information from the basic file system

Question 24

What is the role of the Logical File System in a file management system?

Answer 24

The Logical File System transforms record numbers to byte addresses and verifies if the requested byte address is within file limits.

Question 25

Explain the disadvantages of the Access Control Matrix in file access management.

Answer 25

As files and/or users increase, the matrix size increases, possibly beyond main memory capacity. It may also result in wasted space due to null entries.

Question 26

How are users categorized in the Access Control Matrix to shorten the list?

Answer 26

Users are grouped under categories such as SYSTEM (ADMIN), OWNER (USER), GROUP, and WORLD to shorten the list and categorize access permissions.

Question 27

What are Capability Lists, and what is their primary purpose in file access control?

Answer 27

Capability Lists list every user and their respective file access permissions, allowing control over access to both files and devices

Question 28

What are the two types of algorithms used in data compression, and how do they differ?

Answer 28

The two types of algorithms are lossless and lossy. Lossless retains all data in the file without compromising quality, while lossy removes some data but can compromise file quality.

Question 29

Provide examples of applications suitable for lossless and lossy compression algorithms.

Answer 29

Lossless compression is suitable for text or arithmetic files, while lossy compression is suitable for image and sound files.

Question 30

Explain the process of text compression using symbols and front-end compression.

Answer 30

Text compression involves replacing repeated characters with codes or compressing repeated terms using symbols to represent commonly used words. Front-end compression takes a given number of characters from the previous entry that they have in common.