The magnetic disk uses magnetic technology to read and write bits of data while the optical disk uses light beams. Both disks are used as secondary storage devices where they are used to store user data for future reference.
The main difference between the two types of disks is how they record data and the technology used to read and write. Also, the disk capacity, cost, and data access speed are other differences as discussed in the article.
Magnetic storage disk
The computer hard disk is the main example of a magnetic disk that is used to store files, data, programs, and user data. Magnetic disks are made of disk platters that rotate around a point called the spindle. Other than internal hard disks other types of magnetic disks are external storage devices. Currently, we also have an external portable hard disk. Magnetic disks are being replaced by the solid-state type of flash memory.
Optical storage disk
Optical discs are external storage devices that are made of inexpensive disks that use light to store data. they are mostly used to store multimedia such as music, video, and distribution of software to clients. They are not commonly used today since they are also being replaced by flash memories. Most latest computers and laptops don’t even come with a DVD drive that can be used to read data from these optical disks. You can read a more detailed article here on the types, and functions of the optical disc
Difference between magnetic and optical disk
| Criteria for comparison | Magnetic storage disk | Optical storage disk |
| Material used | They are designed using aluminum, glass, or flexible plastics which are coated with magnetic material (Iron oxide). | Optical discs are made of polycarbonate substrate which is coved with a layer of aluminum. To protect it from scratches it is then coated with acrylic material. |
| Read write speed | Magnetic disks have high read-write speeds compared to DVDs and CDs. A standard hard disk can have an R/W speed of between 80MBs to 160MBs. | Optical disk speed is rated from the original speed. you will find disc indicated 2X or 4X which means 2 or 4 times the original speed. For CDs, the original speed was 150KB/second while for DVDs is 1352.54KB/second. The rating can go as high as 52X. |
| Storage capacity | Magnetic disks like harddisk can have a capacity of even terabytes of data | DVD used to have 4.5GB but now with Blu ray we can have above 32GB of storage |
| Method of data access used | Magnetic disk data is accessed randomly | Optical disks write data in a sequential manner and when reading, it is done the same way. |
| Reuse rate | Magnetic can be reused as many times as possible. Users can delete and store more data at any time | Most optical disks are written only once and read many times. Even those that are rewriteable cannot be done many times. Again due to scratches, they may not last long even just to read data. |
| What used to read and write | It has an electronic read-write head that is moved by a disk arm to read data | It uses laser light to read and write data. For CDs and DVDs, they use red light while Blu-ray uses blue light. |
| Drive mechanism required | The drive and the disk come as a package to enable reading data. it also has an assembly of components that help read and write data | It requires a separate disk drive to read data. The drive can be internal within the computer or can be an external drive connected by a USB cable. |
| Main usage or application area | Used as the computer’s main secondary storage device to store files and data | Mostly used for movies, music, software packaging, archiving data, etc |
| Where data is recorded | Magnetic disks are made up of multiple disks called platters that can record data on both sides | An optical disk can record data only on one side the other side can be used for labeling. However, we have some that can be recorded on both sides but you will need to turn them over. More advanced technology is to have dual layers on the same side having data. |
| Number of revolutions per minute | The disk rotates so that it can read data from the right store location. the speed of rotation is calculated as Revolutions Per Minute (RPM). For a standard magnetic disk, it ranges between 5,400RPM to 7,200 RPM | An optical disk can go for approximately 10,000 RPM depending on the type of disk and drive used to read data. |
| Examples of disk | Hard disk, magnetic tape, floppy disk | CD, DVD, and Blu ray |
Similarities between the optical and magnetic storage disk
- Both disks are used as secondary storage for the permanent future reference of data.
- They are made up of a disk that spins around a central point to access data.
- They require a drive to read data. In magnetic drive is part of the disk while an optical drive is a separate component.
- solid state flash memories are replacing both storage devices since they are faster and smaller in size.
