1. A certain moving arm disk storage with one head has following specifications : Number of tracks I recording surface 100 Disk rotation speed 2400 rpm Track storage capacity= 62500 bits The transfer rate will be

2.5 Mbits/s

4.25 Mbits/s

1.5Mbits/s

3.75Mbits/s

2. A certain moving arm disk storage with one head has following specifications : Number of tracks I recording surface 100 Disk rotation speed 2400 rpm Track storage capacity= 62500 bits The average latency time (assume the head can move from one track to another only by traversing the entire track) is

2.5 s

2.9 s

3.1 s

3.6 s

3. Poor response time are caused by

Process or busy

High I/O rate

High paging rates

All of these

4. Disk sheduling involves deciding

which disk should be accessed next

the order in which disk access requests must be serviced

the physical location where files should be accessed in the disk

none of these

5. Disk requests come to a disk driver for cylinders 10, 22, 20, 2, 40, 6 and 38, in that order at a time when the disk drive is reading from cylinder 20. The seek time is 6 ms per cylinder. If the scheduling algorithm is the closest cylinder next, then the total seek time will be

360 ms

876 ms

850 ms

900 ms

6. Disk requests come to a disk driver for cylinders 10, 22, 20, 2, 40, 6 and 38, in that order at a time when the disk drive is reading from cylinder 20. The seek time is 6 ms per cylinder. The total seek time, if the disk arm scheduling algorithm is first-come-first-served is

360 ms

876 ms

850 ms

900 ms

7. Disk requests are received by a disk drive for cylinders 5, 25, 18, 3, 39, 8 and 35 in that order. A seek takes 5 m sec per cylinder moved. How much seek time is needed to serve these requests for a Shortest Seek First (SSF) algorithm ? Assume that the arm is at cylinder 20 when the last of these requests is made with none of the requests yet served

125 msec

295msec

575 msec

750 msec

8. The maximum amount of information that is available with one position of the disk access arm for a removal disk pack (without further movement of the arm with multiple heads) is

a plate of data

a cylinder of data

a track of data

a block of data

9. An unpaged or read-ahead cache associates disk domains with the address of the read and continues for a specific length. The major disadvantage of unpaged cache is that

it allows cache domain to contain redundant data

it does not allow writes to be cached

its access time is greater than that of paged caching

read ahead cache domain blocks are necessarily fixed in size

10. If a disk has a seek time of 20 ms, rotates 20 revolutions per second, has 100 words per block, and each track has capacity of 300 words. Then the total time required to access one block is

25

30

40

60