Do you know what is Hard disk ( HDD )
A hard disk is part of a unit -- often called a disk drive, hard drive or hard disk drive -- that stores and provides relatively quick access to large amounts of data on an electromagnetically charged surface or set of surfaces. Today's computers typically come with a hard disk that can contain anywhere from billions to trillions of bytes of storage. A hard disk is actually a set of stacked disks, like phonograph records. Each disk has data recorded electromagnetically in concentric circles, or tracks, on the disk. A head, similar to a phonograph arm but in a relatively fixed position, writes or reads the information on the tracks. Two heads, one on each side of a disk, read or write the data as the disk spins. Each read or write operation requires that data be located, an operation called a seek. Data already in a disk cache, however, will be located more quickly. A hard disk/drive unit comes with a set rotation speed varying from 4,200 revolutions per minute to 15,000 rpm. Mos...
