HDD is mainly composed of parts like platters, read-write heads, a motor spindle, etc. All the platters are mounted on the motor spindle in parallel and each storage surface of platters is equipped with a magnetic head.
The magnetic heads move along the radial direction of the platters, coupled with the high-speed rotation of the platters at several thousand revolutions per minute (RPM), so that the magnetic heads can be positioned at a specified position on the platter for reading and writing data.
Therefore, the rotation speed is that of the motor spindle in the HDDs, which also stands for the maximum number of revolutions that the platters can complete in one minute.
In general, the faster the rotation speed, the faster the hard disk can find files, and the higher the transmission speed of the hard disk. Therefore, the rotation speed largely determines the speed of the hard disk.
Currently, the speed of disks can be as high as 15,000 RPM. High-speed hard drives like 10,000 RPM hard drives are generally used in servers and the rotation speed of ordinary hard drives for home use is generally 5400 RPM or 7200 RPM. In this part, I will explain 5400 vs 7200 RPM hard drives to you.
7200 RPM hard drives’ advantage is the high performance. Typically, the more the hard drive RPM, the faster the hard disk. Therefore, 7200 RPM hard drives are usually faster than 5400 RPM hard drives.
For a 7200 RPM hard drive, the time required for each revolution is 60 × 1000 ÷ 7200 = 8.33 milliseconds, and the average rotation latency time is 8.33 ÷ 2 = 4.17 milliseconds. For a 5400 RPM hard drive, its average rotation latency time is 60 × 1000 ÷ 5400 ÷ 2 = 5.56 milliseconds.
In terms of rotation speed, 7200 RPM is at least 15% faster than 5400 RPM hard drives. (Of course, these are just theoretical numbers. The actual hard drive speed is also affected by many other factors.)
In addition, the gap between the 7200 RPM hard drives and the 5400 RPM hard drives is not significant in terms of sequential read and write capabilities. The part that best reflects the performance gap between them is the random read and write capabilities, which affect the read and write speed for fragmented files and program startup speed.
5400 RPM hard drives’ advantages are low energy consumption, low heat production, low noise, and longer lifespan.
When areal density increases on a hard drive, the data becomes more compact. The more compact the data, the quicker the head can get from bit to bit to read and write data. Therefore, data throughput performance improves.