To answer this question, we first need to understand how the file system works.

1. Direct pointers: These are pointers that directly point to a block of data. In this case, we have 10 direct pointers. Since each block is 512 bytes, these 10 direct pointers can point to 10 * 512 = 5120 bytes of data.

2. Indirect pointers: These are pointers that point to a block of pointers, which in turn point to the data. In this case, we have 1 indirect pointer. Since each disk address is 4 bytes, a block can contain 512 / 4 = 128 pointers. Therefore, this indirect pointer can point to 128 * 512 = 65536 bytes of data.

3. Doubly indirect pointers: These are pointers that point to a block of indirect pointers. In this case, we have 1 doubly indirect pointer. Using the same calculation as above, a block can contain 128 indirect pointers, each of which can point to 65536 bytes of data. Therefore, this doubly indirect pointer can point to 128 * 65536 = 8388608 bytes of data.

Now, let's calculate how many disk reads are needed to read all the data from "example.txt", which contains 6000 bytes of data.

1. First, we read the data pointed to by the 10 direct pointers. This requires 10 disk reads.

2. Since the file contains more than 5120 bytes of data, we also need to read the data pointed to by the indirect pointer. However, before we can do this, we first need to read the block of pointers that the indirect pointer points to. This requires 1 disk read.

3. After reading the block of pointers, we can read the data. Since we only need to read 6000 - 5120 = 880 bytes of data, and each block is 512 bytes, we only need to read 2 blocks of data. This requires 2 disk reads.

Therefore, in total, we need 10 (from direct pointers) + 1 (from indirect pointer to read the block of pointers) + 2 (from indirect pointer to read the data) = 13 disk reads to read all the data from "example.txt".

Question

To answer this question, we first need to understand how the file system works.

1. Direct pointers: These are pointers that directly point to a block of data. In this case, we have 10 direct pointers. Since each block is 512 bytes, these 10 direct pointers can point to 10 * 512 = 5120 bytes of data.

2. Indirect pointers: These are pointers that point to a block of pointers, which in turn point to the data. In this case, we have 1 indirect pointer. Since each disk address is 4 bytes, a block can contain 512 / 4 = 128 pointers. Therefore, this indirect pointer can point to 128 * 512 = 65536 bytes of data.

3. Doubly indirect pointers: These are pointers that point to a block of indirect pointers. In this case, we have 1 doubly indirect pointer. Using the same calculation as above, a block can contain 128 indirect pointers, each of which can point to 65536 bytes of data. Therefore, this doubly indirect pointer can point to 128 * 65536 = 8388608 bytes of data.

Now, let's calculate how many disk reads are needed to read all the data from "example.txt", which contains 6000 bytes of data.

1. First, we read the data pointed to by the 10 direct pointers. This requires 10 disk reads.

2. Since the file contains more than 5120 bytes of data, we also need to read the data pointed to by the indirect pointer. However, before we can do this, we first need to read the block of pointers that the indirect pointer points to. This requires 1 disk read.

3. After reading the block of pointers, we can read the data. Since we only need to read 6000 - 5120 = 880 bytes of data, and each block is 512 bytes, we only need to read 2 blocks of data. This requires 2 disk reads.

Therefore, in total, we need 10 (from direct pointers) + 1 (from indirect pointer to read the block of pointers) + 2 (from indirect pointer to read the data) = 13 disk reads to read all the data from "example.txt".

Knowee AI · Accepted Answer