GATE CS 2019 Q42 — File Systems

To find the maximum possible file size, we first calculate the number of disk block addresses that can be stored in a single disk block.

• Disk Block Size ($DB$): $4\text{ kB} = 2^{12}\text{ bytes}$
• Disk Block Address Size: $32\text{ bits} = 4\text{ bytes}$
• Addresses per block ($N$): $\frac{4\text{ kB}}{4\text{ bytes}} = 1024 = 2^{10}$

The inode structure contains:

• $12$ direct pointers
• $1$ single-indirect pointer (points to a block containing $N$ direct pointers)
• $1$ double-indirect pointer (points to a block containing $N$ single-indirect pointers, which in turn point to $N^2$ direct pointers)

The total number of blocks ($B$) accessible is:

The maximum possible file size ($S$) is:

Converting the total size to gigabytes ($1\text{ GB} = 2^{30}\text{ bytes}$):

Rounding off to $1$ decimal place, the maximum possible file size is 4.0 GB.