describe advantages and disadvantages of each allocation method for disk space

 

1. Continuous allocation

Advantages:

(1) The minimum number and the minimum seek time of seeks required to access consecutive files

(2) Easy access to continuously allocated files

(3) Support sequential access and direct access

Disadvantages:

(1) Difficult to find space for new files

(2) Problems with external fragmentation

(3) Difficult to determine how much space should be allocated for a file

 

2.Linked allocation

Advantages:

 

(1) Resolved all issues with continuous allocation (External fragmentation and Size declaration)

(2) Easy to add and expand files

(3) No need to merge disk space

Disadvantages:

(1) Only valid for sequential access to files, does not support direct access effectively

(2) The pointer will occupy space and waste disk space

(3) Insufficient reliability due to the possible loss or damage of the pointer

(4) Lack of performance

 

3.Indexed allocation

Advantages:

 

(1) The use of index blocks solves the problem that link allocation does not support direct access

(2) No external fragmentation

Disadvantages:

(1) Index allocation wastes more space than pointers allocated by linked allocation

(2) Lack of performance