File Allocation Techniques in Operating System: Contiguous, Linked and Indexed

Posted on Oct 27, 2026 in Computers

Explain Different File Allocation Techniques

(7 Marks Answer – Operating System)

Sabse pehle Hindi mein samjho 😊

File Allocation Techniques ka matlab hai hard disk mein files ko store karne ke liye disk blocks ko allocate karne ka tarika.

Operating System mein 3 main File Allocation Techniques hoti hain:

1. Contiguous Allocation
2. Linked Allocation
3. Indexed Allocation

1. Contiguous Allocation

Definition: In this technique, ek file ke sabhi blocks disk mein continuously (ek ke baad ek) store hote hain.

Example:

Disk Blocks:

+----+----+----+----+----+----+
| 1  | 2  | 3  | 4  | 5  | 6  |
+----+----+----+----+----+----+
       File A
       [ 2 ][ 3 ][ 4 ]

Yahan File A ke blocks 2, 3 aur 4 continuously store hain.

Advantages:

• File access fast hota hai.
• Sequential aur direct access dono possible hain.
• Implementation simple hai.

Disadvantages:

• External fragmentation ho sakti hai.
• File ka size badhana difficult hota hai.

2. Linked Allocation

Definition: In this technique, file ke blocks disk mein alag-alag locations par store hote hain aur har block mein next block ka pointer hota hai.

Example:

+--------+     +--------+     +--------+
| Block 2| --> | Block 5| --> | Block 8|
+--------+     +--------+     +--------+
                                    |
                                    v
                                  NULL

Yahan File ke blocks 2, 5 aur 8 linked hain.

Advantages:

• External fragmentation nahi hoti.
• File ka size easily increase kar sakte hain.
• Free disk blocks ka use kar sakte hain.

Disadvantages:

• Direct access difficult hota hai.
• Pointer store karne ke liye extra space chahiye.
• Pointer kharab hone par file ke remaining blocks tak pahunchna difficult ho sakta hai.

3. Indexed Allocation

Definition: In this technique, har file ke liye ek separate index block hota hai, jisme file ke sabhi data blocks ke addresses store hote hain.

Example:

Index Block
+-----------+
| Block 2   |
| Block 5   |
| Block 8   |
+-----------+
   |    |    |
   v    v    v
+---+ +---+ +---+
| 2 | | 5 | | 8 |
+---+ +---+ +---+
 Data Blocks

Yahan index block file ke data blocks ke addresses store karta hai.

Advantages:

• Direct aur sequential access possible hai.
• External fragmentation nahi hoti.
• File ka size badhana relatively easy hota hai.

Disadvantages:

• Index block ke liye extra memory space chahiye.
• Chhoti files ke liye index block ki space waste ho sakti hai.
• Bahut badi files ke liye multiple-level indexing ki zarurat ho sakti hai.

Difference Between Three Allocation Techniques

Conclusion

Operating System mein file allocation ki teen main techniques hain: Contiguous, Linked aur Indexed Allocation. Contiguous allocation fast hoti hai, Linked allocation file growth ko easy banati hai, aur Indexed allocation direct access provide karti hai.

Exam Trick:

• Contiguous = Blocks ek saath
• Linked = Blocks pointers se connected
• Indexed = Addresses index block mein