MadeEasy Test Series: Operating System - File System

Question

A file system with 512 GB disk uses a file descriptor with 16 direct block addresses, 1 indirect block address, 1 doubly indirectly block address and 1 triple indirect block addresses. Size of each disk block is 256 bytes and the size of each disk block address is 8 bytes. The maximum possible file size is____________(in MB).
Ans: 8.26 but in MadeEasy it is 8 how..?

Comments

Given answer is wrong in this test question..

It would be

max possible file size = 8.26

and maximum file size = 8

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Yes,

maximum possible file size  is 8.26

maximum file size = 8 only

their answer is wrong .

Answer 1

max file size =

(db size/ DBA )³*(DISK BLOCK SIZE )

256/8= 32= 2⁵ 

=(2⁵)³* 2⁸

⁼(2¹⁵)*2⁸

=2²³   =8MB

Comments

if they told for max file size than go for triple indirect pointer

if they told for file system size than than go with (16+ 1*(256/8) + 1*(256/8)*(256/8) + 1*(256/8)*(256/8)*(256/8))*256 B

i hope u got now  wt to do when !

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Thanks for the reply. The following example provided by made easy uses a different approach. Please check whether it is correct. Also, could you please explain why would the max file size be limited to triple indirect pointer?

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for max file sizeasnwer will be 4GB.

Answer 2

Whenever file size is being asked , we consider a particular level only..So here :

Maximum file size    =  File size corresponding to triple indirect pointer

As opposed to this , filesystem encompasses all levels , starting from direct to triple indirect here..As the question is about maximum file size possible , we find it as :

Maximum file size  =   File size corresponding to triple indirect pointer

                            =   (Disk block size / Disk block address size)³ * Disk block size

                            =   (256 / 8)³ * 256 B

                            =    2²³ B

                            =    8 MB

Hence maximum file size is 8 MB..

However if asked about maximum file system size then it requires summation of file size at each level..Hence in that case we have :

File system size   =   8 MB + (1 / 4 + 1 / 128 + 1 / 4096 ) MB

                           =   8.26 MB (approx)

Comments

Selected answer in the below link is given differently. Please check.

Maximum file size is asked and they have solved by the method you provided for finding maximum file system size.

https://gateoverflow.in/20440/unix-inode

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Can you please explain the (1 / 4 + 1 / 128 + 1 / 4096 ) MB part in you answer of File system size?

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Maximum File Size =   

Maximum possible file size =

Answer 3

see below link
https://gateoverflow.in/92065/made-easy-test-series#c92266