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Question

Each I-node in file system has 5-direct pointers to disk blocks, 3 single indirect pointers to disk blocks, 2 double indirect pointers to disk blocks and nothing else. A disk block is 400 bytes . A pointer to a disk block is 10 byte. The entire disk contains 15000000 bytes at most. What is the total size of the entire file system.

(A) 1325250 bytes

(B) 1325000 bytes

(C) 1330000 bytes

(D) None.

Answer 1

In 1 Block no.of pointer stored = $\frac{400 \text{bytes}}{10 \text{bytes}} = 40$

Total size of entire file system $= (5 + 3 \times 40 + 2 \times 40 \times 40  )\times 400 \text{bytes} = 1330000 \text{bytes}$

Option C.

Comments

@Shubhgupta,Please may I know one thing that why have u divided 400 by 10. The rest is still understandable since this question is from unix. Please can you tell?

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Actually we nee to find how many addresses are stored in one block. And to address each block 10 bytes is given. So no of pointers in one block will be disk bock size/ pointer size.

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@Shubhgupta,Thanks. :)