The HDD, as shown in Figure 9.12, is considered to be a secondary storage type, right after server memory (that is, RAM memory). As such, it is a computer component that uses the electromotor to spin the disk, and it contains a magnetic read-and-write head and metal platters that permanently store data. Each platter contains tracks and sectors. The starting point for storing data in HDDs is the outer track. The read-and-write head is located above the platter at a distance of microns, thus never touching the disk. If it does, then physical damage occurs.
The data storage capacity is measured in bytes (nowadays, it is GB and TB), while the disc spinning speed is measured in rotations per minute (RPM). The most common RPM ...
