MadeEasy Test Series: Operating System - Disks

Question

A certain hard disk rotates at 6000 rpm. It has 1 KB per sector and average 64 sectors/track and has a seek time of 5 msec. Which of the following statements is/are true?
S1 : The data transfer rate of the drive is 6400 KBPs.
S2 : The time required to read 800 random sectors is 4.13 sec.
S3 : The time required to read 800 successive sectors is 0.0052 sec.

• Only S1 and S2
• Only S2 and S3
• Only S2
• Only S1

Answer 1

Disk perform 6000 Rotation 60 sec.

                    1      "             $\frac{1}{100}$

                    $\frac{1}{2}$  "    $\frac{1}{100}\times \frac{1}{2}$ sec.=5 ms.

Time required for 1 rotation=10 ms.

64 sector rotates in 10 ms.

1    "          "         "  $\frac{10}{64}$ ms.

800  "        "          "$\frac{10}{64}\times 800$=125 ms.

$\frac{10}{64}$ ms. work done 1 KB

  1 ms.                   "       "   $\frac{64}{10}$ KB

1000 ms.               "       "$\frac{64}{10}\times 1000$=6400 KB.

S1: is correct

S2:is incorrect, as we cannot calculate read time of random sector, because the read write head can move from 1 sector to next successive sector only.

S3: is incorrect , as time required for 800 successive sector is .125 sec.

Ans D)

Comments

 srestha how u calculate s2 and s3?

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how you calculated s3?

Answer 2

the answer will be s1 and s2. So, answer is A.