Optical disks are cheap secondary storage disk that uses light to read or write data. They are non-volatile storage devices that are mostly used for data backup.
The main types of optical disks are CDs, DVDs, and Blu-ray among others. They are used for bootable disks, packaging device drivers, movies, MP3 storage, and computer video games. Optical disks are a relatively cheap method of permanently storing data and are simple to use.
Difference between optical disk and drive.
Most people use optical disk and drive interchangeably but they are different components. The optical disk is the reflective disk that carries the data. The optical drive on the other side is the mechanism that holds the disk in place and provides power and facilitates the reading and writing data into the disk.
Unlike the hard disk, the optical drive and disk can be separated.
Functions of an optical drive
The optical drive being the mechanism that enables optical disk operation it offers the following function.
- Provide power to the disk operation.
- Offer read and write mechanism.
- Supply light for reading and writing data.
- Open and close drive components for drive operation.
Uses of the optical disk
Optical disks are used for many purposes by different users and industries. Some of the uses of optical disks include.
- Data back up: they are used to store data permanently for a long period.
- Manufacturer device driver packaging: most companies that produce devices that require drivers use optical drives for packaging.
- Creating bootable disk: optical disks are the main disk used when installing a new operating system on a computer.
- Movies distribution: before the era of youtube and other online streaming platforms optical disks were the main movie storage and distribution media. Some movies distributor are still using DVDs for movies.
- Computer video games: they are used to store video games.
- MP 3 music packaging and distribution: music production used to be distributed by using CD and other optical MP3 disks.
Characteristics of an optical disk
- They are non-volatile
- Use laser light to read and write data.
- Circular in shape disc with a reflective surface.
How optical disk drive works
The optical drive’s main function is to hold the disk in place and provide the laser light that is used in reading or writing data. It also has the mechanism to insert and remove the disk, it also offers connectors to connect to both power and data cables which link the power supply unit and computer motherboard respectively.
The optical disk has one spiral track which moves from the center of the disk to the outer part. It is made up of highly reflective material and uses laser beam light to read or write data.
The disk is made of the pit (dent) and land (flat) which you cannot see with the naked eye. When the light moves to the pit it is scattered and not reflected which represents a 0. If it moves to land the light is reflected (represent a 1) and directed to the sensor where data is read or written. For more on how optical disks work check on the HowStuffWorks page.
Advantages of an optical disk
- They are cheap permanent storage device
- They are simple to use and most personal computers have a disk drive.
- Disks are more durable compared to flash disks.
- The disk comes with a disk casing which makes it easy to carry.
Disadvantages of an optical disk
- Compared to hard disks they have a smaller storage capacity.
- They can lose data if their reflective surface gets scratched.
- For old computers, you need different software to burn content to the disk.
- The user requires knowledge on how to burn data to store the backup.
- They have low data access speed compared to magnetic disks and flash memories.
- An optical disk requires a drive to read and write data.
Types and examples of optical disks
The examples of optical disks can be categorized according to how many times you can read or write on them. CD, DVD, and Blu-ray disks have the same physical size (most of them) but the main difference is the capacity of data that each can carry. CD has a capacity of approximately 750MB, DVD 4.5GB while blue ray can have 128GB.
1. Read Only Memory (ROM)
These disks came with content already written on them. You can only read them as many times as you like but you cannot change anything. They are used mainly by companies that sell a machine that requires to be accompanied by software e.g. printer drivers software.
2. Write-Once, Read-Many (WORM)
They allow the user to write the data in them but only once after that, you cannot change the content anymore. After writing they operate like CD-ROM you cannot edit the content.
3. Re-writable Disk (RW-DISK)
They allow users to write many times and also read many times. Users can burn data to the CD more than once. They are called RW CDs.
4. Compact Disk (CD)
They have the lowest data capacity of all the disks. A conventional disk has a capacity of 750MB. They can carry approximately one movie.
5. Digital Versatile Disk or Digital Video Disk (DVD)
A conventional DVD can carry approximately 4.7GB of data or movie. The versatile is used to store data while the video is for low-definition movies.
6. Blu-Ray disk
It is the latest optic technology and it requires the blue laser ray to read or write compared to others that use laser light. They are mostly used to store high-definition video content.
Troubleshooting an optical drive
- If the drive can`t eject, use a wire and insert it into the hole on the front of the drive
- Drive may be powered but cannot read data which means the data cable connected to the motherboard slot is not correctly connected.
- If you are installing an operating system and it is not booting then you may need to change the boot order in the BIOS setting to make sure you select CD as the first option. Again make sure that the disk you are using is a bootable CD.