Distributed Files System

Question 1

What is the primary purpose of a distributed file system?

Answer 1

To enable programs to store and access remote files as if they were local

Question 2

What are the key requirements for sharing within local networks and intranets?

Answer 2

Persistent storage of data and programs, consistent distribution of up-to-date data

Question 3

What features were added to file systems for data and program sharing?

Answer 3

Access-control mechanisms and File-locking mechanisms

Question 4

What advantages does a well-designed file service provide?

Answer 4

Access to files with performance and reliability similar to, or better than, local disks

Question 5

How does the concentration of persistent storage at servers benefit organizations?

Answer 5

Reduces local disk storage needs and enables better management and archiving of persistent data

Question 6

What additional services can be implemented more easily with a file service?

Answer 6

• Name service
• User authentication service
• Print service

Question 7

What are the responsibilities of file systems?

Answer 7

• Organization of files
• Storage and retrieval of files
• Naming and sharing of files
• Protection of files

Question 8

What is the role of directories in file systems?

Answer 8

To provide a mapping from text names to internal file identifiers

Question 9

What does the term ‘metadata’ refer to in the context of file systems?

Answer 9

Extra information needed for the management of files, including file attributes and directories

Question 10

What elements are typically included in a file’s attribute record?

Answer 10

• Length of the file
• Timestamps
• File type
• Owner’s identity
• Access control lists

Question 11

File systems are designed to manage a small number of files

Answer 11

False

Question 12

What is the purpose of a directory in a file system?

Answer 12

To support the naming of files and allow for hierarchic file-naming schemes

Question 13

What types of operations are summarized for applications in UNIX systems?

Answer 13

System calls implemented by the kernel for file operations

Question 14

The data in a file consists of a sequence of _______

Answer 14

Data items

Question 15

What were the initial offerings of distributed file systems?

Answer 15

Access transparency and location transparency.

Question 16

What requirements emerged in the development of distributed file systems?

Answer 16

Performance, scalability, concurrency control, fault tolerance, and security.

Question 17

What were the potential pitfalls observed in distributed services design?

Answer 17

Many of the requirements and potential pitfalls were first observed in the early development of distributed file systems.

Question 18

What is the importance of the file service in an intranet?

Answer 18

The file service is usually the most heavily loaded service in an intranet, so its functionality and performance are critical.

Question 19

What are the transparency requirements for distributed systems?

Answer 19

1. Access transparency
2. Location transparency
3. Mobility transparency
4. Performance transparency
5. Scaling transparency

Question 20

What is meant by concurrent file updates?

Answer 20

Changes to a file by one client should not interfere with the operation of other clients simultaneously accessing or changing the same file.

Question 21

What standards do current file services follow for locking?

Answer 21

Modern UNIX standards in providing advisory or mandatory file- or record-level locking.

Question 22

In a file service that supports replication, a file may be represented by several copies of its contents at different locations.

Answer 22

File replication in a service

Question 23

Why is fault tolerance important in a file service?

Answer 23

The central role of the file service in distributed systems makes it essential that the service continue to operate in the face of client and server failures.

Question 24

Refers to a model for concurrent access to files where all processes see the same file contents as if only a single copy existed.

Answer 24

Consistency

Question 25

What challenges arise with file replication and caching?

Answer 25

There is an inevitable delay in the propagation of modifications made at one site to other sites, which may result in deviation from one-copy semantics.

Question 26

What security measures do file systems provide?

Answer 26

Virtually all file systems provide access-control mechanisms based on access control lists and require authentication of client requests.

Question 27

What is the goal of efficiency in a distributed file service?

Answer 27

A distributed file service should offer facilities at least as powerful as conventional file systems and achieve comparable performance.