Magnetic storage is a nonvolatile storage that uses different patterns of magnetization on a coated surface to store information. Information is accessed after one or more read/write heads. Examples:
- Floppy Drives/Zip Drives
A floppy drive reads data from removable floppy disks and provides a good method of transferring data from one machine to another.
A floppy disk contains a thin internal plastic disk capable of holding magnetic charges which is protected by a hard plastic casing.
Floppy drives are available in different forms and capacities.
- Hard Drives
Hard drives (fixed drives) store data in a similar way to floppy drives, but they are not removable and have a different physical structure. A fixed disk consists of several stacked hard platters attached through their center by a rotating pole called a SPINDLE. Each platter holds data and has its own read/write head, and all move as a single unit front and back along the stack.
Hard drives can hold much more data than floppy disks. Newer drives have been produced which can hold 500GB of data or more. A typical drive must be divided through formatting into smaller units called CLUSTERS, before it can store data.
- Magnetic tape data storage
The magnetic tape is one of the cheapest methods of storing large volumes of data. Data is recorded across the width of a magnetic tape in rows of magnetic spots and spaces divided into columns of tracks that run the entire length of the tape. Each recording position on a track can be magnetize (for a 1) or not magnetized (for a 0). One track on the tape is not used for storing data, but is used as a control to make sure that the data recorded and transmitted is correct; this is called PARITY TRACK. The tape drive is used to sequentially record (write) onto the magnetic tape and also used to read information from the tape sequentially. Magnetic tape data storage is used for tertiary and offline storage.
