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 |
| Property | Notes |
|---|---|
| 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 |
| Portability | Fairly portable. Too large to fit into a pocket, but will easily fit inside a bag. Can be carried between home/school/office. |
| Durability | 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. |
| Reliability | 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