Hard disc drives are composed of several platters spin around a central axis call the spindle. The faster the rotation faster data can be accessed on the drive. Faster spindle speeds are better. Most laptop hard drives are rated at 5400 Rotations Per Minute (RPM). Hard drives used in most desktop computers spin at 7200 RPM, and a few of the high-performance laptops also have 7200RPM drives. High performance servers and disk storage arrays (NAS/SAN) use hard disk drives that spin at 10,000 or even 15,000 RPM. The higher the rotation speed the greater the cost of the drive.
Now lets’ talk about cache memory.