Storing any data on an optical readable medium is what we call optical storage like CD and DVD storage. To be precise, data are recorded by creating marks in a pattern which can be read back or write again by means of laser light or electromagnetic waves close to visible light spectrum focusing on a spinning disc.There are some optical drives that can only read from discs, whether CD or DVD. But as technology develops, there are already many improvements in optical media. We now have both readers and recorders also known as CD and DVD burners or writers.
Way back, we use video tapes such as VHS and Betamax to watch movies and cassette player to listen to music. But, times have changed! We now have compact discs or CDs, DVDs to replace them and are easy to use and handle. They occupy small place in our room and have better storage capacity. Disc recording is limited only to storing small volume of data such as music, video, pictures and data files. Compact Disc or CD for example, can hold around 700 megabytes while DVD also known as Digital Versatile Disc or Digital Video Disc, can hold around 4.7 gigabytes for single layer type of disc and around 8.5 gigabytes for dual-layered single sided disc. Usually, optical discs are used to store and back up files in small volume of data. But when we talk about storing and backing up the entire hard drive that has hundreds of gigabytes stored data, we can’t. Large backup is usually done on online backup services available on the internet or external hard drives which are too expensive than the optical disc.
If you are going to use CD or DVD to store data, you have to know first how large is your data to be stored. Secondly, know the capacity of the disc whether it will hold all the data or not. There are different type of disc whether CD or DVD. For burning files onto a recordable blank disc such as CD-R, DVD-R, DVD+R, and BD-R, the process is permanent and the media can only be written once. Unlike for rewritable disc such as CD-RW, DVD-RW, DVD+RW, DVD-RAM and BD-RE media disc, the data burning or the process can be erased and replaced. It is because the substance used in rewritable media is different from the recordable media disc.
CD and DVD recording using personal computers was initially a batch-oriented task. It means that the burning process is one at a time only and requires specialized software to create what we call as IMAGE of data to record. DVDs can store more data than CDs because DVDs are higher-density data storage than CDs. There is also less overhead expenses and more area to store than CDs. DVDs come with multi-layer storage characteristics which cannot be found in CDs. The capacity of DVDs varies depending on the type of layer it has. For example; DVD-1 is single-sided single layered disc has 1.46GB capacity, DVD-2 single-sided double-layered disc has 2.66GB capacity, DVD-3 double-sided single-layered disc has 2.92GB capacity, DVD-4 double-sided double-layered disc has 5.32 GB capacity, DVD-5 single-sided single-layered disc has 4.7GB capacity, DVD-9 single-sided double-layered disc has 8.54GB capacity, DVD-10 double-sided single layered has 9.4GB capacity, DVD-14 double-sided single-layered or double layered disc has 13.24GB capacity, and DVD-18 double-sided double-layered disc has 17.08GB capacity.
Another characteristic of optical media storage is what we call as “transfer rates”. You might be wondering the meaning of 1x, 2x, 10x, 16x or 20x in front of the CD or DVD cover. X refers to the number of writing speed of the disc or also known as transfer rate. The higher the speed “x” is, the faster the transfer rate of data onto disc.
Due to the rise of file sharing and piracy, copyright prompted to display notices on CD and DVD packaging to warn consumers of the legality of using the disc.