Question:
Consider a disk with the following specifications: rotation speed of 6000 RPM, average seek time of 5 milliseconds, 500 sectors/track, 512-byte sectors. A file has content stored in 3000 sectors located randomly on the disk. Assuming average rotational latency, the total time (in seconds, rounded off to 2 decimal places) to read the entire file from the disk is ............
Consider a disk with the following specifications: rotation speed of 6000 RPM, average seek time of 5 milliseconds, 500 sectors/track, 512-byte sectors. A file has content stored in 3000 sectors located randomly on the disk. Assuming average rotational latency, the total time (in seconds, rounded off to 2 decimal places) to read the entire file from the disk is ............
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To calculate disk access time, sum up the seek time, rotational latency, and data transfer time.
Updated On: Jan 23, 2025
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Solution and Explanation
The total time to read the file consists of:
Seek time: Average seek time is \(5 \, \text{ms}\).
Rotational latency: For a rotation speed of \(6000 \, \text{RPM}\), the time for one rotation is:
\[
\text{Time per rotation} = \frac{60 \, \text{sec}}{6000} = 0.01 \, \text{sec}.
\]
The average rotational latency is half the time per rotation:
\[
\text{Average rotational latency} = \frac{0.01}{2} = 0.005 \, \text{sec} = 5 \, \text{ms}.
\]
Data transfer time per sector: Each track has \(500 \, \text{sectors}\). The time to transfer one sector is:
\[
\text{Time per sector} = \frac{\text{Time per rotation}}{\text{Sectors per track}} = \frac{0.01}{500} = 0.00002 \, \text{sec} = 20 \, \mu\text{s}.
\]
Total time per sector: Total time to access one sector is:
\[
\text{Time per sector} = \text{Seek time} + \text{Rotational latency} + \text{Transfer time}.
\]
\[
\text{Time per sector} = 5 \, \text{ms} + 5 \, \text{ms} + 20 \, \mu\text{s} = 10.02 \, \text{ms}.
\]
Total time for 3000 sectors:
\[
\text{Total time} = 3000 \times 10.02 \, \text{ms} = 30060 \, \text{ms} = 30.06 \, \text{sec}.
\]
Final Answer:
\[
\boxed{29.5 \, \text{to} \, 30.5 \, \text{sec}}
\]
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