What unit of measurement indicates the speed of a hard drive?

The correct unit of measurement that indicates the speed of a hard drive is revolutions per minute (RPM). RPM measures how many times the hard drive platters spin in one minute, which directly impacts the access speed of data stored on the drive. A higher RPM means that the hard drive can read and write data faster because the read/write head can access the data more quickly as the platters spin.

For example, a hard drive with a speed of 7200 RPM can typically access files more rapidly than one that runs at 5400 RPM, as the higher-speed drive reduces the latency involved in locating and retrieving data. This is particularly significant in traditional spinning hard drives (HDDs), where the platter speed is a critical factor for performance.

While bytes per second, megabytes per second, and gigabytes per hour measure data transfer rates and storage capacity, they do not directly indicate the mechanical speed at which the hard drive operates. Therefore, revolutions per minute is the most relevant measurement when considering the operational speed of hard drives.