W10 - File Management

Question 1

What are some desirable properties of files?

Answer 1

Long-term existences
Sharable between processes
Structure

Question 2

Name file attributes.

Answer 2

Name
Identifier
Type
Location
Size
Protection
Time, and user identification

Question 3

File basic operations.

Answer 3

Create, delete, write, read, open, close

Question 4

Name a few file management system objectives.

Answer 4

-meet data management needs of user
-optimize performance
-guarantee data in file are valid
-minimize potential lost or destroyed data
I/O support for multiple users in multiple-user systems

Question 5

What is the basic I/ supervisor in charge of?

Answer 5

File I/O initiation and termination.
Selection of device for which I/O is performed.
Scheduling disk and tape performance.
Assigned I/O buffers and secondary memory.

Question 6

What is a basic file system responsible for?

Answer 6

Referred to as physical I/O level.

Concerned with placement of blocks on the secondary storage device.

Question 7

Elements included in a file directory.

Answer 7

File name
File type
File organization
Starting address
Size used
Size allocated
Owner

Question 8

What two issues arise in file sharing?

Answer 8

Access rights

Management of simultaneous access

Question 9

What is secondary storage management?

Answer 9

Data structure on a disk that holds files.

Question 10

What information does a Super Block contain?

Answer 10

Size of file system.
Size of file control block area.
Location of the file control block of root directory of the file system.
Times the files was created, modified, last used.

Question 11

Contiguous allocation vs Chain allocation

Answer 11

Contiguous has external fragmentation. Simple. Good performance.
Chain has no external fragmentation. Seeks can be slow. Simple. Each block contains pointer to next block in chain. Files expand and contract. No direct access.

Question 12

Indexed allocation pro and con.

Answer 12

Support direct access.

Contain separate index for each file. Dynamic access without external fragmentation.

Question 13

Chained free portions disadvantages.

Answer 13

Fragmentation.
Everytime you allocate a block you need to read the block first to recover the pointer to the new first free block before writing data to that block.

Question 14

What do each of these contain:

1) In-memory mount table
2) In-memory directory-structure cache
3) System-wide open-file table
4) Per-process open-file table

Answer 14

1) contain information about each mounted volume
2) hold the directory information of recently accessed directories
3) contain a copy of the FCB of each open file, as well as other information
4) contain a pointer to the appropriate entry in the system-wide open-file table