1
Q
define file
A
a set of associated information written secondary storage
2
Q
two types of view in file
A
- logical view - how and properties
- physical view -
3
Q
4 types of file
A
- text
- source
- object
- executable
4
Q
3 file access method
A
- sequential - information is access one record to another
- direct access - information is retrieved when certain key value is identified
- indexed sequential - direct access first then sequential
5
Q
4 directory structure
A
- single-level - single directory
- double-level - master file directory
- tree-structured - file themselves
- acyclic-structured - a directory can be owned by multiple user
6
Q
5 operation on file
A
- read
- write
- execute
- append
- delete
7
Q
2 implementation of file protection
A
- password
- access control
8
Q
3 file allocation methos
A
- contiguous
- linked
- indexed
9
Q
define contiguous allocation
A
every file reside in set of contiguous address
10
Q
two disadvantage of contiguous allocation
A
- locating room for new file
- decide disk space required by new file
11
Q
define linked allocation
A
every file is a linked list in a disk box
12
Q
advantages of linked allocation
A
- no need to state size of file
- does not have external fragmentation problem
- files are able to resume growing
13
Q
disadvantages of linked allocation
A
- breakdown of disk cause loss or damage of pointer
- only support sequential allocation
14
Q
define indexed allocation
A
placing all the pointer all together to index block
- every file has its personal index box which is collection of disk sector
15
Q
why direct access is supported in indexed allocation without external fragmentation
A
- any available block on the disk can fulfil the demand for additional space
