A file system with 300 Gbyte disk uses a file descriptor with 8 direct block…
2012
A file system with 300 Gbyte disk uses a file descriptor with 8 direct block addresses, 1 indirect block address and 1 doubly indirect block address. The size of each disk block is 128 Bytes and the size of each disk block address is 8 Bytes. The maximum possible file size in this file system is
- A.
3 Kbytes
- B.
35 Kbytes
- C.
280 Bytes
- D.
Dependent on the size of the disk
Attempted by 120 students.
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Correct answer: B
Given data:
Block size = 128 bytes
Address (pointer) size = 8 bytes
File descriptor contains 8 direct block addresses, 1 single indirect pointer, and 1 double indirect pointer
Step 1: Calculate how many block addresses fit in one block:
Addresses per block = 128 / 8 = 16 addresses per block
Step 2: Compute data covered by each pointer type:
Direct blocks: 8 × 128 B = 1024 B = 1 KB
Single indirect: one pointer block holds 16 addresses → 16 × 128 B = 2048 B = 2 KB
Double indirect: double indirect points to 16 indirect blocks each with 16 addresses → 16 × 16 × 128 B = 32768 B = 32 KB
Total maximum file size = 1 KB + 2 KB + 32 KB = 35 KB
Answer: 35 KB
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