Which of the following is a unique performance metric of HDDs?

Question

Options

• Acapacity
• Brotational speed
• Cdata transmission rate option
• DIOPS

• A
  11% (2)
• B
  68% (13)
• C
  16% (3)
• D
  5% (1)

Explanation

Rotational speed (RPM) is a metric unique to HDDs because they contain spinning magnetic platters - the speed at which those platters spin (commonly 5400 or 7200 RPM) directly affects how quickly the read/write head can access data. No rotating parts means no rotational speed, which is why this metric simply does not exist for SSDs or other storage types.

Why the distractors are wrong:

• A (Capacity): Both HDDs and SSDs are measured by storage capacity (GB/TB) - not unique to HDDs.
• C (Data transmission rate): Sequential read/write speeds apply to all storage media, including SSDs and flash drives.
• D (IOPS): Input/Output Operations Per Second is used to benchmark all storage devices - in fact, IOPS is more commonly associated with SSDs, which vastly outperform HDDs on this metric.

Memory tip: Think "spin = RPM." If a drive has no spinning parts (SSD, NVMe, USB flash), it has no RPM. The moment you picture a disk physically rotating, you've identified the one metric that can only belong to an HDD.

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