MadeEasy Subject Test: Operating System - File System

Question

A unix I node has 10 direct pointers 1 double indirect, 1 triple indirect and 1 quadruple indirect pointers. Disk block size is 1 byte. If the max number of bytes of a file that can be accessed by quadruple pinter is 4 terabytes using the inode then how many bits are required to address disk bock?

a. 8

b. 16

c. 24

d. 32

 

The answer given at most places is 32.

Answer 1

Given , DB size is 1 Bytes .

we need to find out number of bits in disk block address requires , let it be x bits = x/8 Bytes .

Given , max number of bytes of a file that can be accessed by quadruple pointer is 4 terabytes .

max number of bytes of a file that can be accessed by quadruple pointer =  ( DBSize / DBA )⁴  *  DBSize 

= {1/ (x/8 ) }⁴  * 1

= ( 8/x)⁴

( 8/x)⁴ = 4 TB  =  4 * 1000⁴ byte

now find x from this equation ..

Comments

the value of x does not seem to be right