DVD+Rw or DVD-Rw for DVD Backup?
A Backup Article Contributed by Ashley Lister
DVD+Rw or DVD-Rw for DVD Backup?
There have always been two types of disc used for DVD backup: DVD+RW and DVD-RW. But the choice of which types is best for backing up data is a subjective one.
DVD -Rw for Backup
DVD-RW is a phase-change erasable format that uses similar track pitch, mark length, and rotation control to DVD-R technology. DVD-RW is playable in many DVD drives and players although some drives are confused by the media's lower reflectivity, while others don't recognize the disc format code. The capacity of a DVD-RW is 4.7 billion bytes (or 4.7 gigabytes). DVD-RW discs can be rewritten about 1,000 times which makes them a large capacity and cost effective media for data storage and backups.
DVD-RW drives can write to discs that include DVD-R, DVD-RW, CD-R, and CD-RW.
DVD +Rw for Backup
DVD+RW is an erasable format based on CD-RW technology and has been available since 2001. DVD+RW drives can often read DVD-Rs and DVD-RWs, CD-Rs and CD-RWs. Like DVD-RW discs, DVD+RW discs hold 4.7 billion bytes per side (or 4.7 gigabytes) and they can also encounter the same reflectivity and disc format recognition problems.
When DVD+RW discs were launched promoters claimed the format would be used exclusively for computer data, most specifically computer backups. However, the format is also used for recording movies and sound files.
The technology of the DVD+RW (using phase-change media and a high-frequency groove that eliminates the need for linking sectors), allows DVD+RW discs to be compatible with many existing DVD readers. This means the DVD+RWs are comparatively portable from one machine to another which is a useful feature for any backup media. DVD+RWs can be written to approximately 1,000 times.
DVD+R is a Write Once Read Many (WORM) variation of the DVD+RW. This dye-based medium first appeared in 2002.
Which to Chose for DVD Backup.
The main consideration in making a choice between these two formats is that DVD-RW drives only record on -R and -RW discs, and DVD+RW drives only record on +R and +RW discs. Therefore purchasing the correct media is essential. The worry that one format might triumph over the other, leaving users with redundant hardware and a need for obsolete media is also unfounded. Both formats are currently enjoying equal levels of success.
However, if this really is a concern, a user could always purchase a dual format/combination drive. These drives are more expensive than those designed specifically for + or - formats but they do offer some users peace of mind.
If a user intends to rewrite a backup to the same disc for the length of its lifespan, RWs of either format are obviously going to be the best type of media. If a single backup is required, with no intention of overwriting, either DVD-Rs or DVD+Rs (depending on the format) will be a cost effective and secure choice.
The DVD+RW format does have several advantages when used in a computer but the overall difference is negligible. As long as the backup is being checked regularly, and as long as the necessary media is in plentiful supply, either is equally suitable.
