Commercially-pressed CD's and CD-R or CD-RW disks are fundamentally different technologies, which is why a commercial CD will continue to be readable long after a CD-R has become unusable.
A CD drive uses a focused laser beam that is reflected from the media surface in the CD disc. The beam is reflected onto a sensor that detects changes in the amount of energy that is reflected. The original (commercial) process used perforated aluminum as the media surface. When you use the term "pressed" you are using an old vinyl record term, but the production process is pretty much the same. There is a "master" disk that is put into a press which is filled with polycarbonate. The master disk has little pins sticking up everywhere there is to be a hole in the aluminum. The disk is cooled, and liquid aluminum is spun onto it. This results in an aluminum layer with holes in it.
When the disc is played, the laser reflects strongly from the shiny aluminum or less strongly (or not at all) from the holes. The reflection/non-reflection is translated into the ones and zeros of the binary data stored on the disk.
Over time the aluminum can oxidize or there can be other changes in the plastic and other materials that make the disc unusable. These are long term effects and the ultimate statistical life of a commercial CD is often debated, without conclusion, by the experts.
The CD-R and CD-RW do not use an aluminum media surface. Instead, they use a dye. When the disc is written, a high-powered laser causes spots on the disk to turn dark (hence the term "burning"). When played back, the sensor in the player sees the difference in reflectivity of the dark and not-so-dark spots as the binary data.
Unfortunately, because the dye is a light-sensitive chemical, over time it will fade. This can happen from the heat of the reading laser, from ambient light, and from chemical degradation in the dye and support media.
CD-R/RW media is safe for backup, and for creating alternate media (copying music files to play in your car so that if they are damaged from heat or wear out you can make another one, and preserve your originals elsewhere), and similar purposes. However, they are not safe for archival storage because they are not stable enough for that purpose.
Side note: when burning CD's for use in a car, for best results get "music CD's" which are designed for that application, or slow your burning speed down to 12x or 16x to get a darker spot from your high speed burner. The car will read the disc more reliably.
Insofar as tape storage is concerned, tape is also not a good archival choice of media. It's generally better than CD-R, although I haven't seen any comparative studies.
Major data centers who use tape storage refresh the storage periodically. Their Tape Management System (TMS) remembers the date the tape was recorded, and will call it up to be copied periodically. The old tape is then erased and reused until it reaches end of life (sometimes a fixed usage or time interval, sometimes when the number of recoverable errors reaches a threshold) at which time it is scrapped.
The whole issue of long term archive is complex, and goes beyond media. For media, if a data center stored its files on a 9 track magnetic tape twenty years ago, how would it retrieve that data today (you cannot find working 9 track drives). What if it had used an early Magneto-Optical (MO) drive? Small businesses have trouble when their tape drive fails, and they can't buy another drive in that old format.
File formats are another problem. I have word processing documents that deceased family members created years ago. I no longer have word processing software that will import some of those formats. I can (sometimes) extract the raw text and then try to reformat it in a current program, but if I don't have a printed original I don't know how it was intended to be formatted.
The only archival format that has stood the test of time is paper.
Submitted by: Kevin G. of Dallas, TX
Well, Carl, that so-called expert sure has stirred the waters and a LOT of people are wondering about the same question. However, your friendly Federal Government has studied the problem even longer.
To be specific, the National Archives and Records Administration, in charge of all of the record archiving of the government, has no standard on media storage, and requested NIST, that's National Institute of Standards and Technology, to write a new standard on media durability.
If you never heard of NIST, you're not alone, as NIST is more of a background organization, but suffice to say, they're the ones who creates the standards, references, and accuracy tests for all industries, from DNA to Time accuracy (in fact, if NIST operates one of the Internet "clocks" you can calibrate your PC to). NIST DNA reference material improves forensic DNA test accuracy. NIST also invented closed captioning and many other technology, but enough about NIST.
A gentleman by the name of Fred Byers spent a whole year testing various media, and wrote a guide for NIST to librarians who need to archive information on how to care for optical media such as CD-R and DVD-R's and such. In the guide, he basically stated that with proper handling (store in low humidity, no scratching, stored vertically, etc.) a DVD-R should last 30 years with no fear of losing any information. However, that is NOT an absolute number as it is dependent on a LARGE NUMBER OF FACTORS, some of which in your control, and some not:
Factors that affect disc life expectancy include the following:
? type -- as recordable media is more durable than rewritable media ? manufacturing quality -- you get what you pay for ? condition of the disc before recording -- obvious ? quality of the disc recording -- garbage in, garbage out ? handling and maintenance -- scratches are bad for any discs ? environmental conditions -- humidity and temperature can warp disc, ruining the reflective layer in the media. light, esp. UV light can destroy the dye used in recordable media, etc.
Let us discuss each factor in a bit more detail
All types of media can be damaged through warpage (disc bending), scratches, and reflective layer breakdown due to oxygen leakage.
Recordable media, in addition, is susceptible to UV rays, which affects the dye used in the process.
Rewritable media, with phase-change recording, is even more susceptible to UV ray and temperature.
It is generally acknowledged that certain brands of media are better than others, and often the stuff on sale is not the stuff you may want to buy and keep around.
What you may not know is that there are only like 16 media manufacturers in the world. They make the media for all the brands that you see in the market, and some brands / factories are known to make high grade media (i.e. they tested best for maintaining data integrity, even when the media was subject to aging tests). While few independent labs did comprehensives tests, a test in Europe a while back for CD-R's revealed that Taiyo Yuden (Verbatim), Kodak (Kodak), and TDK (TDK) kept the most data intact.
Condition of the disc before recording
A disc should be brand new when used. While shelf live of a media is up to 5 years, why take chances? Buy them as you need tem.
Handling and maintenance
Scratches are bad for any discs, as it breaks open the substrate layer and allows air to tarnish the inside silver reflective layer inside.
Scratches also can make information on the media unreadable by interrupting the laser's path.
Environmental conditions -- humidity and temperature can warp the media, and exposure to UV light can destroy the dye used in CD-R's and DVD-R's.
Hope that answers your questions.
Submitted by: Kasey C. of San Francisco, CA
In the '80's, the CD was introduced in the market and portrayed as "THE" solution to the vinyl records.
The CD could be thrown in a mud pool, step on it, scratch it, nothing would harm he CD.
Now we all know that CD's has a lower lifetime as their vinyl counterparts and are more susceptible to errors than them. This is also true for the CD as a media to record software.
The early CD's, were recorded at maximum 640 MB. Mostly not even 640 MB but something like 528 MB. This made them less susceptible to scratches.
But as the CD technology was in a constant evolution, overburning a CD to 800 MB and more became common use. Also the DVD was introduced, offering 4/9GB on a wafer of the size of a CD.
It is obvious the the tracks are becoming so small that the finest scratch, the smallest fault, can ruin the CD/DVD forever.
Answering your question, there is no miracle solution to keep CD/DVD from deterioration trough age. But with a little bit of care, you can have many years of pleasure of your recordings.
1. Buy only CD/DVD from a good brand.
Buying low priced CD/DVD will mostly result in very disappointing experiences.
2. Don?t overburn a CD/DVD.
While the overburn technique is now widely accepted by most software, it is still not fully reliable and mostly don?t approved by the CD manufacturers.
3. Put every CD back in the jewel case after use, clean them as prescribed by the manufacturer, and avoid as much as possible touching the reading surface of the CD.
As a final remark, CD/DVD are nowadays not expensive and if you can make a backup of them, make a backup and store it in a safe place.
I use an external harddisk of 250GB (<300 CD's) to store a backup of the CD's/DVD's I have. Price of the harddisk is about 100$.
I have been able many times to rescue recordings which were otherwise lost forever by this harddisk.
Hope this helps,
Submitted by: Carlos
You have just discovered what most people don't discover until they actually lose data: commercial CDs and home-burned CDs are not the same. While a commercial premade CD will last a very long time if it is cared for properly, a home-burned CD will begin to deteriorate. The reason is that the home-burned version uses dyes to accomplish what the premade CD does by having it built into the disk. This is, of course, an oversimplified explanation, but it will suffice.
There are a few ways to maximize the amount of time a CD will last. First of all, buy good quality CDs to begin with. Stick with brand names that you are familiar with and have used successfully in the past.
Do not assume that just because a blank CD is made by a well-known company that it will be high quality.
Test them out by actually using them. One of the best ways to do this is to use them for your regular system backups. Be sure to actually restore from those backups periodically (easier if you have another computer handy that you can wipe out data on) or else use a backup program that allows you to mount the backup as a "virtual drive" and retrieve data from it.
This lets you know if there is a problem with a brand deteriorating unusually fast.
Second, never use labels on CDs. I found this out the hard way. Labels cause the CD to deteriorate much more rapidly than it otherwise would. Certain inks used in pens have been reported to do the same, but I have never encountered this problem, so it shouldn't be too severe. Do be certain, however, that you are gentle when marking CDs. Use a felt tip and do not press hard.
Third, put a note somewhere on the CD that tells you when you made it. This lets you monitor how long it has been since the CD was burned. If the data is irreplaceable, burn it to a new CD every 2 years.
As for the recommendation to use magnetic tapes, that has its own set of problems. Magnetic tapes also deteriorate, and they are subject to some damage that CDs are immune to, notably damage from electrical or magnetic fields.
In short, CDs are good for long term storage-- but don't assume that "long term" means forever. Check them regularly and burn them to new media when problems develop or even before if you can't replace what's on them.
As for storage, that is pretty much common sense. Keep the CDs in a case or an envelope if they are not actually being used. Avoid temperature extremes and handle gently. I also recommend making two copies of every important CD. This practice just saved my data when I discovered that the labels on my CDs had wiped out some irreplaceable family photos. It costs twice as much, but if the data is important to you then it isn't really very expensive, is it?
Submitted by: Denise R. of Lebanon, Missouri
Hi Carl N,
Your question has been set by a lot of people over the last 10 years. I've burned CD in 100s over the years and only found 2 discs with missing information. Lifetime of CDs is not limited due to one parameters only, more issues are setting the limit of lifetime. One is related conditions of storage and how you handle the discs. In other word, how careless or careful you are as the user. Then the material used in the CDs - how cheap a blank CD did you buy. And lastly your burning equipment, that is the laser diode.
When pressed CDs were introduced in beginning of the 80s lovers of vinyl records claimed, that CDs would last for 2 years only. But as you have experienced CDs from this period can still be played. I remember one report from about 1990, which claimed a lifetime of only 3-4 years. Looking into the report, it turned out that the condition of storage was -30C (some -25F) and reading/playing equipment had a worn laser diode. Most of us can only say: I don't store my CDs in the freezer and today?s laser diodes doesn't wear out as they used to.
Turning towards recordable CDs, the whole issue is a matter of having a whole bunch of clear holes placed in circles in a foil. Readability of these holes are depending on a number of issues. How clear are the holes? Is edge of the hole clear? Is the reflectivity of the materials sufficient? Is the laser still as effective as it was? or has the surface become matte? For the early CD-burners this was jeopardized by increasing burning speed and some blank CD had doubtful foil material. Adding, to this some CD-burners were even sold with writing speeds beyond its capability. Many blank CDs were rejected in this period due to bad burners rather than bad discs. It is my conclusion, that this interim period has given us some doubtful discs.
You have to be careful with your CDs and also a little bit extra careful with your own. They don't like heat, bright light, bending, and writing with aggressive writing pens is also nasty. Especially pens with unknown chemicals may etch the CDs, it is just like burning, but this time controlled by the chemicals.
In case you wanna increase the lifetime of your recordings, you may buy CDs which is claimed to 300+ years lifetime. These CDs are referred to as GOLD-CD. These CDs has a special layer which include some 24ct gold. The advantages of these CDs are the ability to create clear holes into it with reduced oxidation or corrosion over time. Amazing almost also unbelievable 300 year. Just 100 years could be great for me. In 10-20 years everything would be transferred to new media type anyway. I saw a report on the 300 years at
Price of these GOLD CDs is 10-20x times the usual ones.
You have been suggested to use magnetic tape. Nor tapes does not last forever. As matter of fact the sound quality decays over time; frequency range is decreased by each use. This loss you can not be restored as with a digital media. Only digital storage keeps its audio frequency range over time and use. Like R&R;DIGITAL media is here to stay. You may call it CD, DVD, MPx, Blu-ray or whatever, but it's digital.
I believe that today?s discs and equipment can provide a disc with sufficient lifetime for most of us and may even restore your more doubtful discs from the early burning time with success. Even discs which are registered as 'No disc' may be restored by copying it today. In case you wanna assure yourselves; let the PC verify the burned disc, this option is normally disabled by default.
What shall I do with my precious discs from the early days? My best recommendation would be to make a new copy, while the old is still readable. This is easy and cheap to most of us today as having two drives in your PC is not uncommon. Lastly, the quality and lifetime of recorded discs is today likely to most depended on your own care.
Submitted by: Leif M. of Helsingor, Denmark
Regarding problems developing over time with recordable CD-R media, I've run into some of this myself, but I also have quite a few discs that were made back when the very first 1x CD burners were made available to the public, and they still read just fine for me.
I suspect that there are several factors involved here.
1. I'm certain there's a difference in quality between brands of CD-R media. A number of my really old CD-Rs that still read flawlessly today were Kodak branded, and were considered expensive "premium quality" discs at the time. They're even physically a little bit thicker than most other media I've handled. By contrast, some of the generic media I purchased because of the low price on 100-pack spindles has actually developed "bubbles" where you can see the dye that's sandwiched between the layers of plastic is disintegrating. (Of course it won't read if small spots are completely gone!) There were/are several different types of dye used for CD-R media, as well, and I wouldn't be surprised if it's turning out that some types have better longevity than others. For example, Verbatim was known for using their trademark blue-tinted dye, while others were shades of green or gold.
2. From what I've read and observed, handling makes a big difference too. Leaving your CD-R's exposed to sunlight (as folks tend to do with music CDs used in their cars or trucks) probably shaves years off of their lifespan. Putting them in some type of jewel-case or sleeve when not in use is a very good idea. Boxes of empty jewel-cases can be purchased fairly inexpensively at most office supply and electronics chain stores.
3. A CD-R holding computer data is inherently more "fragile" and subject to data loss than a CD-R recorded as an audio disc. The standard used for recording audio CDs incorporates quite a bit of error correction information to handle small scuffs and scratches on the media, but besides that, audio data is spread out over a much larger portion of the CD-R. If you have a .ZIP file stored on a CD-R, for example, a pinhole-sized mark someplace on the disc where that .ZIP file is stored can easily be enough to prevent the whole archive from extracting properly. By contrast, the same sized mark might only cause a very brief "stutter" at one point of a song on a music disc (or not pose a discernable problem at all, due to the error correction).
If your audio discs are already deteriorating to the point where players are rejecting them as "unreadable" or they're skipping badly, it sounds to me like things have gotten pretty bad. The only recommendation I'd have is to re-record your music to fresh, good-quality CD-R media and throw out the old ones - and in the future, make a habit of transferring your music to fresh discs every few years or so.
Luckily, in the case of computer software backups, they tend to become so outdated, you no longer really need to keep them by the time the media they're recorded on starts failing. But for those trying to preserve digital photos and the like, I'd recommend this same procedure. Make a fresh set of backups every so often and discard the old media - before it fails on you and you lose something priceless!
Submitted by: Tom W.
CD burned media fails after time.
I am a practicing technician and this is not a new complaint. It is my firm belief that most consumers burn their media at the fastest speed possible for both their software and the media they use. This is fine but there may well be a trade-off in doing this.
What most consumers do not perhaps understand is that commercially produced CD's have actual pits pressed into them that represent the digital data of the original sound data. A burned CD on the other hand is made by fabricating a photo sensitive layer to mimic the pits found in pressed media.
I have found three major causes for this consumers problem they are as
1. A slower burn makes a stronger image representation in the photo
sensitive layer of a burned CD. A faster burn while successful may not impress the photo sensitive layer as effectively as a slow burn. Over time the burn fails as the photo sensitive layer deteriorates.
2. Sunlight and other forms of intense light can effect a burned CD
because it can cause a distortion in the burned media's photo sensitive layer.
3. Scratches by far are more evident on burned media and more easily
caused than on pressed media. Most consumers seem to ignore the manufactures warning and suggestions. Handling of the disc in a careful manner as advised by the manufacturer is the best policy here. I use a camera lens cloth to clean surface of all my media. A camera lens cloth will not scratch the disc surface. Paper and regular household cloths will cause scratches.
Observe the above and I do believe you will have better results.
One more thing always use the media recommended by the burner manufacturer. It is endorsed and guaranteed to work, many of the cheap non name discs out there are just not up to par. Its just like the old cassette tape days.
Most audiophiles went for tapes like Maxell, JVC, Sony etc. but as everyone knows there were a lot of bogus brands out there for the un-informed to purchase.
Submitted by: Peter K.
> I recently read an article by a data storage expert who claimed that
> burned CD-Rs and CD-RWs can be expected to last only two to five years
> and not a whole lot more. I personally have commercially pressed CDs
> from the 1980s that still play fine, but I have begun to notice that
> some of my burned CD-Rs are beginning to skip
you mention that there are basically two types of CDs: Those that are created with all information in place and those you can buy and write on.
The first type is quite robust as the information has been "engraved" into the surface just below the reflector. The most critical part of such a CD is the reflector, most often a very thin layer of aluminum.
The second type of CD works a bit differently: There is a dye layer below the reflector and the information is written onto the CD-R(W) by "burning"
and thereby locally changing the optical properties of the dye. The most critical part is the dye, besides the reflector as above. If the dye degrades the CD easily gets unreadable. The dye of CD-RW is even more critical as it must be "resetable" - another constraint.
> The expert suggests that for secure long-term storage, high -quality
> magnetic tape is the way to go.
This solution is quite expensive as you need a tape drive and enough tape cartridges, but has the advantage of a much larger storage capacity. If the manufacturers say their tape cartridges are reliable for a very long time they have one advantage above CD-R: This type of storage device has been around long enough to prove it. CD-R has been on the market for no more than 10 years.
The best strategy for the private user is: Have a good archive strategy, save often and store the media carefully in a dry, dark, cool place. If you store every file more than once you have a better chance to retrieve it.
There is no real alternatives to CD-R. Use high-quality ones. Do not use any DVD variety as their reliability is much less. DVD may be used for an image backup of your boot drive so you can restore your present configuration for the months to come.
Submitted by: Alexander V.
Unlike pressed original CDs, burned CDs have a relatively short life span of between two to five years, depending on the quality of the CD. There are a few things you can do to extend the life of a burned CD, like keeping the disc in a cool, dark space, but not a whole lot more.
The problem is material degradation. Optical discs commonly used for burning, such as CD-R and CD-RW, have a recording surface consisting of a layer of dye that can be modified by heat to store data. The degradation process can result in the data "shifting" on the surface and thus becoming unreadable to the laser beam.
Many of the cheap burnable CDs available at discount stores have a life span of around two years, In fact, there are some of the better-quality discs offer a longer life span, of a maximum of five years. Distinguishing high-quality burnable CDs from low-quality discs is difficult, I think because few vendors use life span as a selling point.
I've had good luck with Verbatim media, and bad results with TDK. Playback with the TDK discs I used degraded steadily over time, in spite of very little use, and not much in the way of scratches or other blemishes on the disc. On the other hand, the Verbatim discs I've used have held up well over time, and under more use than the TDK ones I used.
Opinions vary on how to preserve data on digital storage media, such as optical CDs and DVDs. I have my own view: To overcome the preservation limitations of burnable CDs, I?m suggesting using magnetic tapes, which, as I read, can have a life span of 30 years to 100 years, depending on their quality. Even if magnetic tapes are also subject to degradation, they're still the superior storage media.
But I want to point out that no storage medium lasts forever and, consequently, consumers and business alike need to have a migration plan to new storage technologies.
A Good Question to get in this subject is Does Burning Speed makes difference in quality of CDs? Someone told me that the burning speed makes a difference in the quality of the records. The lower it is, the deeper it burns and therefore the better the quality is. I heard that there are some audio technicians decide to burn masters at 2x and copies at 4x due to getting digital noise from higher burn rates. Might just depend on the burner quality and the burning program...
Hoping you get the Point of my explanation.
Submitted by: Sameer T.
Everyone who owns a business is always trying to be enticed by the security and the longevity of magnetic tape. And although I'm apt to agree with them on its durability, I don't use it to back up important data in my business. I have two problems with magnetic tape vs. CD or DVD. The first problem is hardware. Data backed up on a CD or DVD can be loaded into any computer with a drive capable of handling the media. The same can be said about tape backup, however you are more likely to find a computer off the shelf with a compatible CD or DVD drive vs a magnetic tape drive. The other problem is the need for long term storage.
As a business owner, I'm backing up my important data every one to three days. I've been using CD-RW media to do this for years. If a disk gets corrupt, you can reformat it using your burning software, then use it again. If you are concerned about your CD becoming corrupt, simply burn two or three. The cost of three CD or even DVD media is much more reasonable than the cost of one of those tapes. And if my server dies, I can buy any computer at any store, and load the data onto the new computer right away and I'm back in the game. I have several people trying to convince me of the benefit of a paper backup system. I find it easier (and cheaper) to have multiple electronic backups. My business server has a RAID 1 card and two hard drives which mirror each other. I have the CD backup, and I then take this data and save it to a secure partition on another machine in a separate location.
The likelihood of all of these systems failing at one time is highly unlikely. And if it does, I'm taking the day off, because that's just real bad luck. As far as long term storage (like music), I've noticed that CD-RW can lose the data in the long haul, but haven't had any problems with CD-R media. I have some that skip, but not for a reason I didn't know about. I buy the large spools of CD-R which don't come with jewel cases. So these disks get abused. If you know you are going to keep something for a really long time, I would make sure the disks you buy have jewel cases. And you can apply the multiple disk system with this as well. The media is easy on the wallet, and the more backups you have, the lower the risk you will actually lose the data.
I don't think I answered all the questions, but that's my take.
Submitted by: Dave K.