A DVD-RW disc is a rewritable optical disc with equal storage capacity to a DVD-R, typically 4.7 GB. The format was developed by Pioneer in November 1999 and has been approved by the DVD Forum. Unlike DVD-RAM, it is playable in about 75% of conventional DVD players. The smaller Mini DVD-RW holds 1.46 GB, with a diameter of 8 cm.
The primary advantage of DVD-RW over DVD-R is the ability to erase and rewrite to a DVD-RW disc. According to Pioneer, DVD-RW discs may be written to about 1,000 times before needing replacement, making them comparable with the CD-RW standard. DVD-RW discs are commonly used for volatile data, such as backups or collections of files. They are also increasingly used for home DVD video recorders. One benefit to using a rewritable disc is if there are writing errors when recording data, the disc is not ruined and can still store data by erasing the faulty data.
One competing rewritable format is DVD+RW. Hybrid drives that can handle both, often labeled "DVD±RW", are very popular due to the lack of a single standard for recordable DVDs.
The recording layer in DVD-RW and DVD+RW is not an organic dye, but a special phase change metal alloy, often GeSbTe. The alloy can be switched back and forth between a crystalline phase and an amorphous phase, changing the reflectivity, depending on the power of the laser beam. Data can thus be written, erased and re-written.
There is now a new format called DVD-RW2. Older DVD burners are not all forward compatible with this new standard.
The current fastest speed a DVD-RW disc can be written to is 6x speed, with many at this speed having DVD-RW2 capabilities.
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