How Long Do CDs, DVDs, and Tapes Last?
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.
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 show 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.