TTTK 2833 - Assignment 4 (Question)

Assignment 4 ( File System )
Due on 25/3/2010

Please show all work on a separate sheet attached to this sheet.
1. What is a file descriptor?

2. What are the file descriptors for stdin, stdout, and stderr, respectively.

3. What functions are used to duplicate a file descriptor?

4. What is a block special file? Give an example of a block special file.

5. What is a character special file? Give an example of a character special file.

6. What is the essential difference between a block special file and a character file?

7. Consider a disk with a mean seek time of 9.4 msec, a rotational rate of 7,500 rpm, and 524,288 bytes per tarck. What are the data rates for block siezes of 8 KB and 16 KB, respectively?

8. A file system checker has constructed the counters shown below:
 Block number 0 1 2 3 4 5 6 7 8 9
In use 1 0 0 2 1 0 1 0 1 1
Free 0 1 1 0 1 1 0 0 0 0

Are there any errors? If so, how serious are they (can they be fixed)? Explain.

9. The performance of a file system depends upon the cache hit rate (fraction of blocks found in the cache). If it takes 1 msec to satisfy a request from the cache, but 17 msec to satisfy a request if a disk read is needed:
a. Give a formula for the mean time required to satisfy a request if the hit rate is h.
b. What should the hit rate be to satisfy a request less than 9 msec?

10. What is the Distributed Denial of Service Attack?