8. Digital Versatile Disk (DVD)
DVDs are amongst the most common methods of copying and backing up data at home.
A DVD is similar to a CD in that it is an optical device and that a laser is used to store the data and read the data.
A single layer DVD can store about 4.7Gb of data.
A double layer DVD can hold over 9Gb of data.
One problem with the DVD is that the different companies which make them have not agreed on a standard format.
Because of this, you will see various kinds of DVD disks for sale: DVD-R, DVD+R, DVD-RW and DVD+RW. You have to make sure that you buy the right kind of disk to go with your DVD equipment.
|Advantages of DVDs||Disadvantages of DVDs|
|Very large storage capacity 4.7-9 Gb||DVDs do not work in CD drives|
|Sound and picture quality is excellent, making them ideal for storing films with video and sound.||There is no single standard of DVD|
|DVDs are now mass produced so they are relatively cheap||They can be easily damaged by breaking or scratching|
|DVD drives can read CDs|
|Type of storage||Optical|
|Data access||Direct access|
|Cost of storage||DVDs cost more per byte of storage than hard disks, magnetic tapes or flash memory. They are less expensive than CDs per byte of storage.|
|Capacity||4.7 (single layer) to 9 Gigabytes (double layer)|
|Speed||Slower than a hard disk or flash memory, faster than magnetic tape|
Fairly portable. Too large to fit into a pocket, but will easily fit inside a bag. Can be carried between home/school/office.
Easily scratched by general wear and tear or by not protecting it in a plastic case. Scratches on the disk surface can damage the data being stored
Needs to be protected from extremes of heat.
Has a limited number of read/write cycles.
If scratched, the data might not be able to be read.
Needs a computer with a DVD drive in order to read the disk. Cannot be read by a CD drive.
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: DVD