Difference between Optical Disk and Magnetic Disk

Optical Disk vs. Magnetic Disk

The principal difference between the optical disk and the magnetic disk lies in the way the computer uses them to either read information from them or to write data into them. Computers and laptops write and read data from an optical disk using a visible light laser (optically), whereas, it reads and writes data into the magnetic disk by using the principles of electromagnetism.

Comparison Chart

Comparison BasisOptical DiskMagnetic Disks
Type of MediaIt is a single removable disk, used for secondary storageIt is a group of several Fixed disks, which is used for secondary storage.
Sampling RateHighLow
Signals to noise ratioOptical disks provide an Excellent signal to noise ratioThese Disks offer intermediate signal to noise ratio
UsageThrough the use of optical disks, a large number of replicas of information can be made.A computer can use only one Magnetic Disk at a time, for the purpose of storage and retrieval of data
TracksSpiral or Circular TracksCircular Tracks
Access TimeOptical Disks require Longer Access TimeMagnetic Disks need comparatively shorter access time than that of the optical disk

The above table has been fabricated for catering you with all the information that you would require to draw a comparison between these two types of disks:

Optical Disk

The optical disk is a secondary external storage device, which stores data digitally. Optical drives are created using polycarbonate which is a resin. The top microscopic pitted surface of the optical disk is glazed with materials like Gold and Aluminum for giving the Disk a shiny and reflective surface. The information stored in an optical disk is read by projecting laser light upon the optical disk which is rotated by a motor. The information is stored digitally in the surface of the optical disk in microscopic pits. All the stored information stored in the microscopic pits can be read by projecting laser beams on the surface. If the laser beam falls on the pits, then it is reflected back. If a laser beam is reflected, then it is considered “1”, and if the laser beam is not reflected back then it has fallen on the “land” part of the optical disks and is considered to be “0”. In this way, information is stored and retrieved digitally from the optical disk.

Magnetic Disk

It is a secondary information storage device, which uses different magnetic patterns to read and write data upon a magnetizable medium for the purpose of storing and retrieving information. Magnetic Disk consists of a group of Circular Platters, which are made up of Non-magnetic metals like aluminum. These circular platters are called substrate and are layered with a magnetic film. The magnetic disks in a computer are placed on a spindle which spins the disc around so that the read and write heads of the drives can read from or write to disk, respectively.  A magnetic Disk comprises of concentric tracks. The Information in the magnetic disk is stored and retrieved from its concentric tracks. Each Track is divided into a number of sectors and sectors of the magnetic disk stores a block of data in the magnetic form.  The functions of Reading from or Writing to a magnetic Disk is done through magnetization. The Magnetic Disks use a magnetic charge for reading and writing to the disk, where the direction of the flow of the charge decides whether the digital signal under consideration is 1 or 0.

Key Differences

  • The magnetic Disk is fixed within a computer and cannot be moved from one place to another, on the other hand, optical disks are truly portable and can be carried from one place to another.
  • In terms of signal to noise ratio, the optical disk is better than the magnetic disks
  • The optical disks provide better sampling rate in comparison to the Magnetic Disk.
  • For accessing data in an optical disk, we have to sequentially go through all the data before the required data (Sequential access), on the other hand, Data can be accessed randomly in a magnetic Disk.
  • The optical disk tracks are generally spiral shaped, whereas, the tracks of the Magnetic Disks are Circular in shape.
  • Speaking about quantity, only one magnetic disk can be used at a time. On the contrary, a large number of Optical Disks can be used to replicate any given information.
  • The Access time of the Optical disk is lower than the access time of the Magnetic Disks.
  • Magnetic Disks provide a large capacity of the memory for secondary storage, whereas, the optical disks can only store a little amount of the information.

Video Explanation

The above mentioned video will be helping you to precisely and adequately differentiate between both the optical disk and the magnetic disk and other storage types. The concept of Optical Disk and Magnetic Disk caters a plethora of differences. However, some of the core differences which is responsible for making the choices are well explained.

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