GATE 2022 CS – Question 63
Consider two files systems $A$ and $B$, that use contiguous allocation and linked allocation, respectively. A file of size 100 blocks is already stored in A and also in B. Now, consider inserting a new block in the middle of the file (between 50th and 51st block), whose data is already available in the memory. Assume that there are enough free blocks at the end of the file and that the file control blocks are already in memory. Let the number of disk accesses required to insert a block in the middle of the file in $A$ and $B$ are $n_A$ and $n_B$, respectively, then the value of $n_A+n_B$ is _________.
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Correct answer: 153
Explanation
Contiguous (A): shift blocks 51–100 by reading and writing each (50×2=100) and write the new block, so $n_A=101$. Linked (B): read 50 blocks to reach the 50th, then write the new block and update the 50th block's pointer, so $n_B=52$. Sum $=153$.