Mass Storage Devices and Backup Media

In computing, the function of a mass storage device is to hold, or store, a large amount of information, even when the computer’s power is off. Unlike information in RAM, files kept on a mass storage device remain there unless the user or the computer’s operating system removes or alters them. Many types of mass storage devices are available, including those that store data on magnetic media, devices that use optical technologies, and devices based on solid-state technology. Note that this list includes both removable and fixed (nonremovable) devices. Further, certain of these, depending mostly on their interfaces, are hot-swappable devices, and many can be considered backup media. Let’s explore all these dimensions.

Magnetic Mass Storage

Magnetic mass storage devices used with computers are those that store digital data on magnetized media, such as floppy disks, the metal platters in hard disk drives, and magnetic tape media used in tape drives. Unlike RAM memory, which is erased when power to the device is turned off, this type of storage is nonvolatile. Read/write heads are used to create magnetic patterns on the media. Following are descriptions of three types of devices that can save data onto magnetic media: floppy disk drives, hard disk drives, and tape drives. Note that the terminology differs slightly: magnetic media are called “disks,” whereas optical media are called “discs.” Don’t let it confuse you; they are both devices that spin and write and read data.