The DVD-RAM

DVD-RAM (DVD–Random Accessfull use of the advantages of DVD-RAM. There are
Memory) is a disc specification presented in 1996 byalso a number of video cameras that use DVD-RAM
the DVD Forum, which specifies rewritable DVD-RAMas the recording media.
media and the appropriate DVD writers. DVD-RAMEvaluation
media have been used in computers as well asAdvantages of DVD-RAM
camcorders and personal video recorders since 1998.Long life — without physical damage, data is
Currently there are three competing technologies forretained for 30 years minimum.
rewritable DVDs: DVD-RAM, DVD+RW andCan be rewritten over 100,000 times (DVD±RW
DVD-RW. DVD-RAM is considered a highly reliablecan be rewritten approx. 1,000 times). Faster
format, as the discs have built-in error control and aDVD-RAMs support fewer rewrites (3x speed:
defect management system. Therefore, DVD-RAM is100,000, 5x speed: 10,000), but still more than
perceived to be better than the other DVDDVD±RW. (Remember, these are theoretical
technologies for traditional computer usage tasks suchnumbers. In practice they could be smaller depending
as general data storage, backup and archival, thoughon the drive, the treatment of the disc and the file
the Mt. Rainier standard for DVD+RW lessens thissystem.)
somewhat. Curiously, DVD-RAM has a largerReliable writing of discs. Verification done in hardware
presence in camcorders and set-top boxes than inby the drive, so post-write verification by software is
computers, although the DVD-RAM's popularity inunnecessary.
these devices can be explained by the fact that it isDisc defect management safeguards data.
very easily written to and erased, which for exampleWrite speed twice as fast (when verification not
allows extensive in-camera editing.enabled) as DVD±RW. (Note: 12x DVD-RAM
The on-disc structure of DVD-RAMs is closely relatedspec = 16 DVD±RW spec. As of 7/24/06,
to hard disk and floppy disk technology, as it storesDVD±RW write speed was at 8x
data in concentric tracks. DVD-RAMs can be(DVD±RW specifications) while DVD-RAM is at
accessed just like a hard or floppy disk and usually12x (DVD-RAM speed specification).)
without any special software. DVD-RWs andDVD-burning software may not be required
DVD+RWs, on the other hand, store data in one long— discs can be used and accessed like a
spiral track and require special packet reading/writingremovable hard disk. Mac OS (8.6 or later) supports
software to read and write data discs. It is a commonDVD-RAM directly. Windows XP supports DVD-RAM
misconception that DVD-RAM uses magneto-opticaldirectly only for FAT32-formatted discs. Device drivers
(MO) technologies: DVD-RAM is a pure phase changeor other software are needed for earlier versions of
medium, similar to CD-RW or DVD-RWWindows or if one wants to use the decidedly better
Many operating systems like Mac OS (Mac OS 8.6 orUDF format rather than FAT32.
later), Linux and Microsoft Windows XP supportEasier to use than other DVD technology.
DVD-RAM operation directly, while earlier versions ofVery fast access of smaller files on the disc.
Windows require device drivers or the program InCD.2 KB disc block size wastes less space when writing
The optical drives shipped with most Apple Macintoshsmall files.
computers do not support DVD-RAM operation, but aFinalization not necessary.
third party DVD-RAM-compatible drive can beMedia available with or without protective cartridges.
connected and used directly with Mac OS.In video recorders, DVD-RAM can be written to and
Windows XP can only write directly to FAT32watched (even separate programs) at the same time,
formatted DVD-RAM discs. For UDF formatted discs,much like TiVo.
which are considered faster, compatible device driversSupports time slip recording and recording without
or software such as InCD or DLA are required.border in/out writing.
Windows Vista can natively access and write to UDFDisadvantages of DVD-RAM
formatted DVD-RAM discs. This is a non-issue withLess compatibility than DVD+RW and DVD-RW (as
Linux however, which allows the use of virtually anynoted above).
file system of the multitude that ship with the operating12x media is not readily available in the USA and will
system, including UDF. Mac OS can read and writenot be available in the US and Europe in the near
HFS, HFS Plus, FAT and UDF formatted DVD-RAMfuture due to low market demand. 16x media may not
discs directly. It is even possible to use the ext3 filebe available anywhere except manufacturers' R&D
system on a DVD-RAM disc. So while it is possible tolaboratories.
use any filesystem one likes, only very few performDVD-RAM media is more expensive than other DVD
well on DVD-RAM. This is because some file systemstypes. 12x media is expected to cost almost $9 per
frequently over-write data on the disc and the table ofdisc, at least initially, but this price will fall as production
contents is contained at the start of the disc.ramps up.
Many DVD standalone players and recorders do notDVD-RAM writing will be slower than DVD+RW and
support DVD-RAM, especially older or cheaperDVD-RW until 12x DVD-RAM media becomes
versions. However, within the "RAMPRO" (DVD RAMavailable. If write verification is enabled, the writing
promotion) group are a number of well-knownspeed is decreased by about half. Using FAT32
manufacturers of standalone players and recordersinstead of UDF may also slow DVD-RAM
that DO support DVD-RAM. Panasonic for instanceperformance.
have a range of players and recorders which make