CS3050, Spring 2007 – File Structures
Homework 3
Due March 14, 2007

1. Do exercise 12 on page 113 in our text.

2. A disk has 512 byte sectors, 10000 tracks per surface, 4 double sided platters, average seek time of 10 msec. The number of sectors per track varies. The inner most 2000 tracks have 300 sectors per track and each successive 2000 tracks have 350, 400, 450 and 500 sectors per track.

a. What is the capacity of each surface, and the disk?

b. If the disk rotates at 7200 rpm, what is the maximum rotational delay?

c. What is the maximum data transfer rate in KB/sec?

d. Suppose a 4096 byte data block size is chosen. A file of 100,000 records of 100 bytes each is stored on the disk. How many blocks are required for the file?

e. What is the time required to read the file, if the blocks are stored contiguously on the inner most tracks?

f. What is the time required to read the file, if the blocks are stored contiguously on the outer most tracks?

3. Suppose we have a tape drive as follows:

Tape density: 5000 bpi

Size of interblock gap: 0.3 in

Length of tape: 2400 ft

Tape speed: 200 ips

And a file with:

Number of records: 1,000,000

Bytes per record: 100

a. Find the blocking factor my_BF that will store the file on the tape with the least amount of unused tape.

b. Compute the amount of tape needed for BF=60.

c. Compute the Effective Recording Density for BF=my_BF and BF=60.

d. Compute the Effective Transmission Rate for BF=my_BF and BF=60.