Last Quiz

Question 1

What is a file

Answer 1

Contiguous logical address space

Question 2

What are the types of data stored in files

Answer 2

Numeric
Character
Binary

Question 3

What are some attributes of files?

Answer 3

Name
Identifier
Type
Location
Size
Protection
Time, date and user identification

Question 4

What are some file operations?

Answer 4

Create
Write
Read
Reposition within file, ie seek
Delete
Truncate
Open
Close

Question 5

What is needed to manage open files?

Answer 5

Open file table
File pointer
File open count
Disk location of the file
Access rights

Question 6

What is the Open File Tables?

Answer 6

Tracks open files

Question 7

What is the File Pointer?

Answer 7

Pointer to last read/write location per process that has the file open

Question 8

What is the File open count?

Answer 8

Counter of number of times a file is open to allow removal of data from open file table when last processes closes

Question 9

What is the disk location of the file?

Answer 9

The cache of data access information

Question 10

What is the Access rights?

Answer 10

Per process access mode information

Question 11

How is file locking implemented?

Answer 11

Use shared locks and exclusive locks similar to reader writer locks

Question 12

What is the difference between mandatory file locking and advisory file locking?

Answer 12

In mandatory file locking access is denied depending on locks held and requested and advisory processes can find statuses of locks and decided what to do

Question 13

What are the two usual access methods?

Answer 13

Sequential access, and direct access

Question 14

In sequential access how is the file read?

Answer 14

Byte by byte in order

Question 15

In direct access how is the file read?

Answer 15

The pointer shifts to the position specified by the input

Question 16

What is the entity containing file system known as?

Answer 16

Volume

Question 17

What does each volume track in the file systems info?

Answer 17

The device directory or the volume table or contents.

Question 18

What is a directory structure?

Answer 18

A collection of node containing information about all files

Question 19

A directory structure is organized logically to obtain what?

Answer 19

Efficiency, naming and grouping

Question 20

How is a single level directory organized?

Answer 20

By having a single directory for all users

Question 21

How is a two level directory organized?

Answer 21

Each user has a separate directory

Question 22

How is an acyclic graph directories organized?

Answer 22

By having shared subdirectories and files

Question 23

What is a File structure?

Answer 23

A logical storage unit and collection of related information

Question 24

Where does the file system reside on?

Answer 24

Secondary storage

Question 25

What is the file control block?

Answer 25

A storage structure consisting of information about a file

Question 26

What is the device driver?

Answer 26

Controls the physical device

Question 27

What is the layers of the file system?

Answer 27

Application programs->logical file system-> file organization module->basic file system-> I/O control->devices

Question 28

What do device drivers do?

Answer 28

Manage I/O devices at the I/O control layer

Question 29

What does the basic file system do?

Answer 29

Converts commands to the device drivers

Question 30

What does the file organization module do?

Answer 30

Understands files logical addresses and physical blocks

Question 31

What does the logical file system do?

Answer 31

Manage metadata information Translates file names into file numbers, file handles, location by maintaining file control blocks.

Question 32

What is typically held in the File Control Block?

Answer 32

Data blocks, permissions, size, and dates

Question 33

What are mount tables?

Answer 33

They store file system mounts, mount points, and file system types

Question 34

What does the directory structure do?

Answer 34

Organizes the files

Question 35

What does the system wide open file table do?

Answer 35

Contains a copy of the FCB of each file and other info

Question 36

What is the Per process open file table?

Answer 36

It contains pointers to appropriate entries in the system wide open file table as well as other info

Question 37

What are the two ways a directory may be implemented?

Answer 37

With a Linear list or with a hash table.

Question 38

What is the benefits and downsides of implementing a directory with a linear list?

Answer 38

Benefit: simple to implement Downside: Linear search time (ie time consuming)

Question 39

What is the benefits and downsides of implementing a directory with a Hash Table?

Answer 39

Benefit: Reduces the search time Downside: Has to deal with collisions and only useful if the entries are a fixed sized or uses chained overflow method

Question 40

What are the three allocation methods?

Answer 40

Contiguous, linked, indexed

Question 41

What are the benefits and downsides of using the contiguous allocation method?

Answer 41

Benefit: Best performance, and simple to implement Downside: Need to find space on the disk for a file, knowing the file size ahead of time may be difficult, external fragmentation (need a compaction method)

Question 42

What are the benefits and downsides of using the linked allocation method?

Answer 42

Benefit: No external fragmentation, improves efficiency of space usage Downside: Unreliable, locating a block can take a while, must still deal with internal fragmentation

Question 43

What are the benefits and downsides of using the indexed allocation method?

Answer 43

Benefit: Simple, versatile Downside: Can improve throughput through clustering

Question 44

What are extent based file systems?

Answer 44

File systems that allocate disk blocks in extents, where an extent is a contiguous block of disks

Question 45

What is the free space list?

Answer 45

A list that keeps track of available blocks.

Question 46

What are some ways to recover data from disks?

Answer 46

Consistency checking, backing up and restoring the data from the backup