DVD-RAM (DVD–Random Access Memory) is a disc specification which specifies rewritable DVD-RAM media and the appropriate DVD writers. That is to say that DVD-RAM is a type of rewritable DVD and the term also refers to the technology capable of reading the discs. Introduced in 1996 by the DVD Forum, DVD-RAM media has been used in computers as well as camcorders and personal video recorders since 1998.
There are three competing technologies in the world of rewritable DVDs. The three types of DVD in competition are DVD-RAM, DVD+RW and DVD-RW. DVD-RAM is considered the most highly reliable format because the discs have built-in error control as well as an effective defect management system. Indeed, in general terms, DVD-RAM is perceived to be better than the other DVD technologies for traditional computer usage tasks such as data storage, data backup and archiving.
DVD-RAM also has a larger presence in camcorders and set-top boxes than in computers. The popularity of DVD-RAM in these devices can be explained if we take into account that data is very easily written to and erased from DVD-RAM, which allows for extensive on-board camera editing and live channel updates and interactive services in set-top boxes.
Structurally speaking, the on-disc configuration of DVD-RAMs is closely related to both the hard and floppy disk technologies insofar as it stores data in concentric tracks. DVD-RAM discs can normally be accessed like a hard or floppy disk without any specialist software whereas the competition (DVD-RW and DVD+RW discs) store data in one long spiral track and require special packet software to read and write data.
The main advantages of using DVD-RAM include the long-life and estimated uncorrupted storage time of thirty years, and they can be rewritten over 100,000 times compared with 1,000 rewrites for the other types of DVD. The writing process is also highly reliable as verification is done inside the hardware by the drive, so post-write verification by software is simply unnecessary. This process is also further protected by the disc defect management system which is designed to safeguard data.
As stated above, DVD-burning software may not be required because the disc space can be accessed like a hard drive of floppy disk. DVD-RAMs also offer incredibly fast access to small files on the disc and they save more space by offering small 2KB disc block sizes for writing small files. DVD-RAM is supported by most Windows and MAC programs not to mention high-grade security digital video recorders.
The format is not without disadvantages. Even though it predated competitive technologies, DVD-RAM is less compatible than DVD+RW and DVD-RW and some features of the format cannot yet be explored as the readers have not yet been created.
Similarly, DVD-RAM media is and always has been more expensive than other types of DVD. Still, the RAM format really is the most reliable of the three for most needs.
So, there you have it, a brief history and explanation of the DVD-RAM format and the pros and cons of using it in practical circumstances.