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DVD technology is a natural progression from CDs so,
regardless of format, DVD disks share many common features with their CD
cousins. A DVD is the same size as a CD and employs the same phase change
technology. This generates an immediate benefit - backward compatibility with
CDs – your shiny new DVD-ROM drive can read all of your old CDs. The vast
majority of DVDs are supplied as a bare disk, rather than employing a protective
casing. Unfortunately DVDs are just as vulnerable as CDs to damage by dust,
fingerprints and scratches – be gentle with them. The phase change
recordable technology (both CD-R & DVD-R) uses an organic dye polymer which
can be degraded by UV light - including sunlight. Careful storage of recordable
CDs and DVDs is crucial to data retention.
The comparison between DVD and CD continues through the
writable and rewritable formats with the primary difference being the superior
capacity of DVD over CD.
All formats are recognised by the DVD industry standards
body - the DVD Forum -except +RW - a Sony/Philips design - at present this
format is not fully developed for production. While DVD-ROM is the main
consumer format, a number of DVD formats are available for use in the IT data
storage market.
CD-R has been around for over a decade now, and at £130
for a drive and £1 for a cartridge, CD-R technology has reached a price
point that consumers and businesses find extremely attractive for simple backup
- leaving little margin for resellers. DVD-R, however, is still very expensive
at around £5000 for a drive. This is because of the need to obtain a
Content Scramble System (CSS) license from the DVD Copy Control Association.
Without the CSS, content pirates could make an infinite number of illegal copies
without loss of quality – bad news for film studios and software producers.
The final format group is the rewritable DVD family - the CD
equivalent, CD-RW is well
established. As an IT data storage medium the main players are DVD-RAM and
DVD-RW as well as the developing +RW. The three formats within this
dysfunctional family are surprisingly almost totally incompatible.
DVD-RW (from Pioneer) - based on the existing CD-RW - has a
capacity of 4.7GB. DVD-RW is read compatible with most DVD drives - however it
has its drawbacks - the cartridge will only rewrite 1,000 times.
DVD-RAM offers a higher degree of flexibility, as well as
the promise of an enormous 9.4GB (double sided) capacity in the near future.
Having been available in the UK for more than a year, the price of DVD-RAM
drives has now fallen to a level within the budget of many SMEs. The high
storage capacity and long lifespan (100,000 rewrites) will convince most company
accountants that this is a sound investment. Random access means that the speed
of data storage and retrieval is much faster than tape storage solutions. On
the negative side, DVD-RAM is less compatible than DVD-RW, requiring a 3rd
generation DVD-ROM drive to read it.
In the computer industry CDs have long been used for the
distribution of documentation, manuals and reference material. CD libraries
(jukeboxes with drives, a robot, and storage slots) have also become popular for
allowing reference material to be shared across computer networks. Because of
their increasing cost effectiveness in terms of cost per gigabyte, DVD libraries
are starting to take this role. DVD-RAM libraries are also being used as
near-line storage devices for accessing data which can be changed but needs to
be quickly accessed – not filed away in a cupboard or safe in a dusty
storeroom never to be seen again.
As with MO (Magneto Optical) technology, DVD-RAM in
jukeboxes offers a more robust storage solution than tape. Some suppliers (such
as Maxoptix) house the disk within a protective cartridge, as recommended by the
DVD Forum. Maxoptix DVD-RAM jukeboxes also incorporate a robot to flip the
media. This enables you to utilise both sides of the disk, and hence the full
capacity of 5.2GB (soon 9.4GB) per cartridge. These jukeboxes offer flexibility
and scalability, with 20 to 1600 slots (104GB to 8.3TB). Other DVD-RAM
jukeboxes derived from their CD cousins use bare media, and do not have a
flipping mechanism - meaning only half the capacity of each disk can be
realised. As a rugged, high capacity storage device, with quick data retrieval,
a DVD-RAM jukebox is ideal – particularly for networked reference files,
requiring a large amount of space such as audio-visual and video files.
If a permanent solution for archiving information is
required then MO technology should be considered. It is less susceptible to
damage by sunlight, and is physically protected against dust and fingerprints.
This reliable media can be rewritten 100 million times.
As with all storage devices, each DVD format is suited to
different applications – although DVD alone does not offer the complete
storage solution. As a storage medium one of the 'write many' formats is most
suitable, although there is still some uncertainty as to which format will
become the most prevalent. For creating a master copy of a large document, such
as a multimedia presentation, or a corporate promo, DVD-R provides the necessary
capacity and protects the original material from editing.
So is DVD a hot ticket?
It is clear as prices continue to fall that DVD offers
useful new solutions to the IT market in terms of storage and data transfer.
The development of an additional storage method increases the opportunity for
resellers to precisely match storage solutions to consumer requirements. ...Maxoptix profile | 
