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Media
Guides > Longevity: How Long Do CDs/DVDs/Tapes Last?
Updated April 2008
Contrary to popular belief, optical media is not new. Optical
media was developed and patented in the 1960s, not long
after magnetic video tape. As time went on, and with much
research and development from companies like Pioneer,
Philips and Sony, optical storage became a viable media
format in the early 1980s with the release of the
CD-ROM.
About four years ago, several fluff articles about
"dying media" were published online and
sometimes even repeated in print. Those articles were little more than opinion pieces
that lacked perspective on the
overall technology of optical media, as well as ignored
decades of empirical evidence. None of them (as seen by this
author) are backed by formal studies from neutral sources. A
lot of them read like scare-tactic Fox News broadcasts, or
bedtime stories about the boogeyman.
To make matters worse, quite a few dot-com
"transfer services" have popped up
on the Internet in the last few years. Individuals run
down to the local Best Buy or Walmart and grab a DVD
recorder, thinking they can suddenly open a video conversion
business and get rich. And it never fails, one of their
primary marketing tactics is to scare potential customers
with doomsday messages about how their VHS tapes are dying
(or otherwise only have a lifespan of a few years) and must
be transferred immediately.
There is no need to be scared. Your CDs, DVDs and VHS
tapes are not disintegrating on the shelves.
Be sure to read the other media guides
and reviews to better understand the DVD format and
blank discs.
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Optical
Media is Progressive Generational Technology
As the the decades progressed, formats like CED, Laserdisc,
CD-R, CD-RW, Magneto-Optical Disc, minidisc, mini-CD,
DVD-ROM, DVD-RAM, DVD-R, DVD-RW, DVD+RW, DVD+R, mini DVD-R,
PSP disc, DVD+R DL, and DVD-R DL filled the shelves of
stores. Future ones include BD-ROM, BD-R, and HD-DVD. And
that only includes the ones easily available to consumers
for audio, video and computer data.
All optical share various properties which are improved
upon with succeeding generation of disc:
- All pressed media involve 3 basic ingredients: metal,
plastic (polycarbonate) and glues.
- All recordable media involve 4 basic ingredients:
stabilized dyes, metal, plastic (polycarbonate) and glues.
In other words, DVD technology is not new. It builds upon
the earlier generation formats, including Laserdisc, CD-ROM,
CD-R and CD-RW. The most important advancements made with
DVD were the obvious data size increased (narrower writing
tracks), as well as the inclusion of an upper-layer
protective polycarbonate and the accompanying glues (also
improved).
So when it comes to longevity studies, there is plenty of
valid data that goes back more than 25 years upon which to
extrapolate results.
The "Disappearing Data" Myth and Why Discs
"Go bad"
The most common complaint online by end-users is they are
"suddenly" unable to access data on an optical
disc. But instead of calmly trying to understand the
situation, they run to online user forums, insist that their
"data has disappeared" and that the media in
question is an unreliable brand, manufacture or technology.
There is no patience, no careful consideration. It's bad,
they know it, and the case is closed in their mind.
It's the easy answer. And it's incorrect. In almost all
cases of "disappearing data" a little more
research and patience will reveal the true reason for the
inability to access data.
Disc reflectivity. As discussed elsewhere in the blank media
guides, disc reflectivity is
one of the leading causes of a known-good disc refusing to
play or freeze in the DVD-ROM or DVD-Video player. Quite
often, the data access problem is discovered on a drive or
player that the disc has never been used in. The combination
of disc materials and player laser is just not agreeable.
Use another player or DVD-ROM. But not just any player or
DVD-ROM, use a good one that is well-known for working with
more-stubborn discs. BTC DVD burners and Toshiba DVD players
are suggested for this task.
Drive or player lasers. Optical media lasers have a
very finite lifespan. In fact, optical media will far
outlive players. In 50 years, assuming we have not nuked
ourselves from existence, society potentially faces a
situation where discs will exist with no way to retrieve or
play the information stored on them, unless
backwards-compatible technology exists at that time. Lasers
weaken as time goes on, and eventually they shut down
altogether. Its not uncommon to find a DVD player that can
only read CDs because the DVD laser died and the CD laser is
still going strong. Cheap DVD players typically only last
6-24 months, while the better-made units can go on for 5 or
more years. The solution here is to try a better or newer
player or drive.
The disc was always bad. Most people never check any
of their discs when they are burned. It's difficult for data
to disappear or be inaccessible if it was never correctly
burned on a disc in the first place. Proper testing methods
for optical media is discussed elsewhere in the blank media guides. If data is important, test it
thoroughly at the time the disc is burned.
User error. Sometimes even the most simple
explanations are overlooked. For example, be sure the DVD or
CD is not in the player upside down. As silly as that may
sound, it's been seen before. Other user errors include
improper authoring (whereas a DVD "plays fine" on
a computer, but not the DVD-Video player), the burn was
incomplete (files missing), or handling mistakes. All of
these things would usually be found when testing the disc.
Storage and handling considerations. Optical discs
are a frail format, physically speaking. It does not take
much effort to destroyed a 1mm x 4.75-inch plastic CD/DVD
platter. Is a disc durable to normal use? Yes, absolutely.
Is it indestructible to brute force or improper storage?
Absolutely not. Some plastic DVD cases and CD/DVD wallets on
the market are poorly made, and will warp the disc. A warped
disc will not play or read correctly, if it can be read at
all. Scratches, fingerprints, dust, dirt, smudges, and scuff
marks –
or any similar damage done to the read side of a disc
–
will cause the laser to refract improperly and thus be
unable to read the information stored on the disc. If a disc
has been ruined in this manner, the only option available in
most cases is to take it to a professional disc restoration
service, one that will buff out or re-surface the disc,
maybe attempt to undo the warping, and then copy it onto a
new disc.
Sticky labels. DVD media was not made to be used with
sticky labels. In fact, neither was CD media, but the wider
grooves left a wider margin for error in reading the data.
Sticky labels, regardless of how carefully one tries to
center the label when applying it to the disc surface, will
cause serious disc imbalance, as well as often weigh the
disc down (which, in turn, forces the player to exert more
effort to spin the disc at the required rotational
velocity). DVD media has data grooves that are less than
1/7th the width of ones found on CD media, and are far more
likely to show problems when compared to a labeled CD. And
whether or not they are sold in stores by respected
companies, remember that lots of stupid products are on the
market. For DVD media, soapy water and a soft towel will
often remove the offending label. For CD media, there is no
real solution, as removing the label will undoubtedly remove
the disc metals. If you really need images on a disc,
consider buying inkjet media and a CD/DVD printer.
Pressure. Because some optical formats do not have
protective upper layers of plastic to protect the metals and
dyes, exerting downward force could damage the disc.
Silver-top or cheaply-printed CD is most affected, while a
protective-covered DVD is immune. Wallets, stacking items on
top of discs, and individuals with a Superman grip are
common causes for pressure-related problems. The solution
here is to be more careful in the future, and hope software
like ISO
Puzzle can retrieve the undamaged portion of the disc.
Extreme temperatures and other mishandling. Discs are
intended for indoor use with normal living conditions, stored
carefully in cases in a safe environment. Discs left in the
sun, in a hot car, in a freezer, chewed on by a dog, or
anything else unusual or irresponsible will kill a disc.
This is more advanced than user error, this is outright
neglect.
Optical Phase-Change
Media
Unlike dye-based
or pressed media, phase-change
crystalline surfaces can degrade rapidly, whether the disc
has been used or not. In time, these particles begin to break
down, sometimes in as little as 6 months. The most common
tell-tale sign is small craters form in the disc surface,
causing unreadable areas. These craters can range from the
size of a penny to the size of a pinhead, so they can be
difficult to see with the naked eye. But because data is
written into tiny grooves, especially DVD data, the smaller
crater can cause catastrophic loss of information.
Phase
change media was created for temporary re-usable situations.
It is not archival and should never be used for something
that needs to be kept longer than a few weeks. Some
empirical data suggests that DVD-RW lasts longer than
DVD+RW, and that DVD-RAM is not as affected by this
(although not entirely immune). The simple solution is to
not use phase change media except when absolutely needed for
temporary storage.
Longevity
Advantages of Optical Media
What optical media detractors like to forget is that optical
media was developed to overcome the shortcomings
of magnetic tape formats, and it has very much
succeeded:
- Normal tape playing. Tape formats were degraded every
single time the tape passed across the mechanical parts of
recorders and players.
- Worn and improperly maintained tape players. Poorly
maintained tape equipment could seriously damage a tape.
Tape could get wrapped around the heads and other various
gizmos inside a tape player or recorder. Dirty heads would
especially scratch and harm the data portion of the tape,
more than normal playing would do.
- Tape player malfunctions. Every time the tape was
inserted into the player, there was serious concern that the
tape could be "eaten" by equipment malfunction,
with the various rollers and transport mechanisms, thereby
losing the content of the tape forever.
- Tapes open to the elements. Magnetic tapes are open
to the elements, and the primary reason the format has an
average lifespan of 10-30 years is because oxygen and
humidity eat away at the chemicals and metals as they
naturally age.
- Clumsy tape mistakes. Most tapes would break apart
and the contents disemboweled on the floor if dropped even
from waist-height distances. Early tapes had no cartridge at
all and would roll along the floor, while the tape casually
stuck to any piece of lint or foreign matter in its path.
Optical media addressed these
issues in several ways:
- Normal disc playing. At no time does an optical disc
come into contact with mechanical reader parts, on the data
surface of the disc. While it is true that an arm can grab a
disc on a slot-loader, or that a centerpiece grabs the disc
to spin it, those only touch non-data surfaces of the media.
Some slot loaders are manufactured defectively, leaving tiny
scratches on the data surface of the disc, so replace
problematic drives when identified. Removing the brush from
the front of the slot usually corrects this.
- Worn and improperly maintained disc players. For the most part, a malfunctioning
optical media drive will simply not read the disc, and eject
it. There
are some uncommon incidents where a malfunctioning optical
drive can shatter a disc from spinning it too long or with
too much force, or where a drive will "spit out" a
disc and it shoots across the room, but these are unlikely
incidents that many people will never experience or even
witness first-hand.
- Disc player malfunctions. As mentioned already, at
no time does the data portion of the disc come into contact
with the reader equipment.
- Discs not open to the elements. CD media,
unfortunately, left the upper layer of data potentially
exposed to the elements, and it was not hard to entirely
destroy a CD by scratching off the silver lacquer surface,
and thereby exposing the dye to oxygen. Better made CDs have
a durable branding silkscreen that seals and protects the
foil layer from easy damage. Laserdisc had issues with metal
too, as the initial choice in aluminum foils led to the
widespread problem of "laser rot" or "disc
rot" –
a term reserved for Laserdisc problems. DVDs
have an upper layer of polycarbonate to protect the foil.
The contents of the disc are glued shut and inaccessible by
humidity and oxygen, to a point. Eventually the elements
will attack and permeate the glue, but not for several
decades.
- Clumsy disc mistakes. Discs are lighter, and they
should not smash apart during a clumsy moment. There are
cases where a disc taps against a hard floor at an
inopportune location along the edge of the media, and the
glues come apart, thus destroying the data. The data surface
can also be scratched or scuffed, as well as become dirty.
This issue has been addressed with products like Verbatim
Video Guard discs, and will likely be corrected in the next
generation of optical media.
Lifespan of Optical
Media
Tests performed by manufacturers often range from 30-100 years
before disc contents are naturally destroyed and the data
cannot be accessed. Independent research has shown these
numbers to be more realistic in the 25-50 years category,
which is plenty of time to enjoy the contents of the media,
and then move the contents to the next viable storage format
in a couple decades.
Of course, these calculations depend on discs being stored
and used under normal circumstances, in typical household or
office environments. Locations with unusually extreme
conditions maybe lessen that by several factors, although
the life will still be one of many years. An outdoor storage
shed in Antarctica, for example, is probably not too
hospitable. Neither would be a hut in the middle of the
Amazonian rain forest. Those situations are
naturally-occurring accelerants that induce increased
lifespan reduction.
CD media can break down a bit faster than DVD due to the way
the discs are constructed, especially the cheap CD-R and
CD-ROMs that leave all or part of the metal foils exposed.
Microscopic holes will form in the exposed metals, and
craters will form in the dye (very similar appearance to phase change media craters) due to oxidizing. Some CD label
glues are also known to be corrosive to the metals.
Other rare optical media ailments include metal- and
plastic-eating bacteria, although it is only possible in a
few tropical places in the world, and this microorganism
behavior is atypical. It looks like tapeworms are sandwiched
in the disc, quite disgusting. The cause for this is largely
unknown, as the rarity makes it hard to research.
Ironically, there have even been some studies that shown
recordable media could outlast pressed media, because of the
extra care that has been put into the various recordable
materials.
These are, of course, mean averages. There will always be
the unusual disc that dies in two years and the one that
lasts 100 years, but such occurrences will not be
widespread. Most people who feel they belong in this minority
will still likely be incorrect, and should refer to the myth
section above.
Lifespan of
Magnetic Tape Media
While clearly inferior to optical media, magnetic tape is
not too far behind its laser-written brother. Tape media
varies greatly from format to format. The larger and thicker
broadcast/studio/archival tapes that have been reinforced
chemically to repel the elements can last several decades,
and there are tapes that can still be read after 30-40
years.
At the other end of the spectrum are consumer formats like
VHS, which start to degrade within 10-25 years. Most of the
video tapes manufactured in the 1970s and 1980s tend to be
more durable than the thinner and cheaper tapes that flooded the market
in the 1990s and are still sold new today. There are also
various grades of VHS tape, from standard consumer, to
advanced consumer, to professional and broadcast grades; the
particle density and tape perfection being the primary
discrimination between the grades.
The older a tape gets,
the more likely it will face problems like oxide shedding
and tape-eating bacteria. The replay count will also affect
the level of degradation.
VHS tapes owned by consumers and recorded in the
1980s-1990s should last another 10 years on average. There
is no need to rush them into transfer. But now is the time
to start. They are approaching the end of the life cycle.
Take your time and do a good job. There is no need to worry
about doing it fast, as they are not rotting apart on the
shelf while you "waste time" reading this page.
When it comes to commercially-available movies and shows,
just go buy yourself the official DVD release, if one
exists. It's wasteful to try and convert these items. Save
self-done transfers and transfer service work for the more
precious home movies and other rarities that may have been
bought or recorded through the years.
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