Operating System Unit 5

PART – B (16 MARKS) 
1. Write about the kernel I/O subsystem.
2. Explain the various disk scheduling techniques
3. Write notes about disk management and swap-space management.
4. Suppose that a disk drive has 5000 cylinders, numbered 0 to 4999. The drive is
currently serving a request at cylinder 143, and the previous request was at cylinder 125.
The queue of pending requests, in FIFO order, is
86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130
Starting from the current head position, what is the total distance ((in cylinders) that the
diskarm moves to satisfy all the pending requests, for each of the following disk
scheduling
a. FCFS
b. SSTF
c. SCAN
d. LOOK
e. C-SCAN
5. Compare the performance of C-SCAN and SCAN scheduling, assuming a uniform
distribution of requests. Consider the average response time (the time between the
arrival of a request and the completion of that request’s service), the variation in
response time, and the effective bandwidth. How does performance depend on the
relative sizes of seek time and rotational latency?
5. Explain Disk management in detail
6. Explain the various I/O data transfer schemes
7. Explain the various application I/O interface
8. Write note on (i) Disk attachment
 (ii) Streams
 (iii) Tertiary Storage
9. What is RAID? Explain its various levels