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[checks articles] ....ugh. Is that seriously it?Three months?

Wear retention on flash is kind of a bummer for time capsules and Stargate style ancient repositories of knowledge. An old school PC with a bios in mask rom should be able to boot up given power in hundreds of years time, assuming the hard disks don't have some sort of failure mode that happens when they are un-powered.

A modern machine has firmware in flash and also a flash drive. Both of which would end up blank in a few years to a few decades depending on technology with more recent being worse.

If I were rich I'd pay for some mask Roms of Wikipedia and bury them around the world. That way if the shit hits the fan and we end up in a dark age people could dig them up when civilisation is rebooting.

The other option would be some optical disks.

http://www.cd-info.com/archiving/kodak/index.html

If the industry standard specification of BLERmax less than or equal to 220 had been used as the end-of-life criteria, then this same analysis would predict that with 95% confidence, 95% of the population of Kodak Writable CD discs will have a data life of greater than 12,000 years.

Aw yeah! 12,000 years is about the time from neolithic revolution to now.

Then again a masked Rom in one of those wikipedia readers seems like you have the advantage of not needing to find or build a working CD Rom drive. Mind you, whoever digs it up is still going to have to work out how to build a display because I don't see any display technology lasting for 12,000 years underground.

how do you explain my 10+ year old game CDs that are still in perfect shape then? CD's degrade in 5-10 years if you give them to someone who isn't a geek, doesn't have a helpful OCD, and someone who simply doesn't care. even my burned discs which I didn't care about are still in readable condition and are more than 5 years old. keeping CD's and DVD's in a time capsule, and thus in a dark, dry place, will allow them to work for several decades. TDK even says metal stabilized Cyanine discs will last up to 70 years at standard storage conditions Click Here. Meaning 50 years is easily achievable with just an educated assumption of safe storage settings.

If you're relying on a CD or DVD to keep your stuff forever, I hope you're following these guidelines for "Prolonging CD-ROM's Life Expectancy".

Sorry, but you are misinformed. The I in RAID does in fact stand for inexpensive, since when RAID was created the alternative was a Single Large Expensive Disk (SLED). That fact that this alternative is now obsolete and the I has been co-opted to mean independant so that folks like you would get its meaning doesn't change the history. But then again, you probably think that the V in DVD stands for video

CD-RWs are expected to last about 25 years under ideal conditions (i.e. you write it once and then leave it alone). Repeated rewrites will ccelerate
this. In general, CD-RW media isn't recommended for long-term backups or archives of valuable data.

The rest of this section applies to CD-R.

The manufacturers claim 75 years (cyanine dye, used in "green" discs), 100 years (phthalocyanine dye, used in "gold" discs), or even 200 years
("advanced" phthalocyanine dye, used in "platinum" discs) once the disc has been written. The shelf life of an unrecorded disc has been estimated at
between 5 and 10 years. There is no standard agreed-upon way to test discs for lifetime viability. Accelerated aging tests have been done, but they may not provide a meaningful analogue to real-world aging.

Exposing the disc to excessive heat, humidity, or to direct sunlight will greatly reduce the lifetime. In general, CD-Rs are far less tolerant of environmental conditions than pressed CDs, and should be treated with greater care. The easiest way to make a CD-R unusable is to scratch the
top surface. Find a CD-R you don't want anymore, and try to scratch the top (label side) with your fingernail, a ballpoint pen, a paper clip, and
anything else you have handy. The results may surprise you.

Keep them in a cool, dark, dry place, and they will probably live longer than you do (emphasis on "probably"). Some newsgroup reports have complained of discs becoming unreadable in as little as three years, but without knowing how the discs were handled and stored such anecdotes are
useless. Try to keep a little perspective on the situation: a disc that degrades very little over 100 years is useless if it can't be read in your
CD-ROM drive today.

One user reported that very inexpensive CD-Rs deteriorated in a mere six weeks, despite careful storage. Some discs are better than others.

An interesting article by Fred Langa (of http://www.langa.com/) on http://www.informationweek.com/story/showArticle.j html?articleID=15800263&pgno=1
describes how to detect bad discs, and discusses whether putting an adhesive label on the disc causes them to fail more quickly.

By some estimates, pressed CD-ROMs may only last for 10 to 25 years, because the aluminum reflective layer starts to corrode after a while.

One user was told by Blaupunkt that CD-R discs shouldn't be left in car CD players, because if it gets too hot in the car the CD-R will emit a gas that can blind the laser optics. However, CD-Rs are constructed much the same way and with mostly the same materials as pressed CDs, and the temperatures required to cause such an emission from the materials that are exposed would
melt much of the car's interior. The dye layer is sealed into the disc, and should not present any danger to drive optics even if overheated.
Even so, leaving a CD-R in a hot car isn't good for the disc, and will probably shorten its useful life.

See also http://www.cd-info.com/CDIC/Technology/CD-R/Media/ Longevity.html,
especially http://www.cd-info.com/CDIC/Industry/news/media-ch ronology.html about some inaccurate reporting in the news media.

See "Do gold CD-R discs have better longevity than green discs?" on http://www.mscience.com/faq53.html.

CD-RWs are expected to last about 25 years under ideal conditions (i.e. you write it once and then leave it alone). Repeated rewrites will ccelerate
this. In general, CD-RW media isn't recommended for long-term backups or archives of valuable data.

The rest of this section applies to CD-R.

The manufacturers claim 75 years (cyanine dye, used in "green" discs), 100 years (phthalocyanine dye, used in "gold" discs), or even 200 years
("advanced" phthalocyanine dye, used in "platinum" discs) once the disc has been written. The shelf life of an unrecorded disc has been estimated at
between 5 and 10 years. There is no standard agreed-upon way to test discs for lifetime viability. Accelerated aging tests have been done, but they may not provide a meaningful analogue to real-world aging.

Exposing the disc to excessive heat, humidity, or to direct sunlight will greatly reduce the lifetime. In general, CD-Rs are far less tolerant of environmental conditions than pressed CDs, and should be treated with greater care. The easiest way to make a CD-R unusable is to scratch the
top surface. Find a CD-R you don't want anymore, and try to scratch the top (label side) with your fingernail, a ballpoint pen, a paper clip, and
anything else you have handy. The results may surprise you.

Keep them in a cool, dark, dry place, and they will probably live longer than you do (emphasis on "probably"). Some newsgroup reports have complained of discs becoming unreadable in as little as three years, but without knowing how the discs were handled and stored such anecdotes are
useless. Try to keep a little perspective on the situation: a disc that degrades very little over 100 years is useless if it can't be read in your
CD-ROM drive today.

One user reported that very inexpensive CD-Rs deteriorated in a mere six weeks, despite careful storage. Some discs are better than others.

An interesting article by Fred Langa (of http://www.langa.com/) on http://www.informationweek.com/story/showArticle.j html?articleID=15800263&pgno=1
describes how to detect bad discs, and discusses whether putting an adhesive label on the disc causes them to fail more quickly.

By some estimates, pressed CD-ROMs may only last for 10 to 25 years, because the aluminum reflective layer starts to corrode after a while.

One user was told by Blaupunkt that CD-R discs shouldn't be left in car CD players, because if it gets too hot in the car the CD-R will emit a gas that can blind the laser optics. However, CD-Rs are constructed much the same way and with mostly the same materials as pressed CDs, and the temperatures required to cause such an emission from the materials that are exposed would
melt much of the car's interior. The dye layer is sealed into the disc, and should not present any danger to drive optics even if overheated.
Even so, leaving a CD-R in a hot car isn't good for the disc, and will probably shorten its useful life.

See also http://www.cd-info.com/CDIC/Technology/CD-R/Media/ Longevity.html,
especially http://www.cd-info.com/CDIC/Industry/news/media-ch ronology.html about some inaccurate reporting in the news media.

See "Do gold CD-R discs have better longevity than green discs?" on http://www.mscience.com/faq53.html.

• Shedding Some Coherent Light on CD-R
• CD-R Media Longevity
• The New Dyes Cast: Mapping the CD-R Media Market
• Which disks to use [Marantz]
• CD Factories

• Shedding Some Coherent Light on CD-R
• CD-R Media Longevity
• The New Dyes Cast: Mapping the CD-R Media Market
• Which disks to use [Marantz]
• CD Factories

Only for the last 10 years.

...media longevity?

Kodak "predicts (at the 95% confidence level) that 95% of properly recorded discs stored at the recommended dark storage condition (25C, 40% RH) will have a lifetime of greater than 217 years."

Granted I usually buy stuff that is not RIAA affiliated thanks to the RIAA Radar, but I prefer the CD because it looks nice and it's a great way to ensure that my investment is safe. I just rip the CD as some oggs and add them to my playlist.

Here's one reference. There are probably others you can find. I can tell you from personal experience of examining "burned" CD-R's with an AFM that there are deformations in the plastic.

I'm not quite sure what you mean by "pits are burned into plastic" and "the difficulty of precision coating the dye". If you don't have a nice even layer (down to a few nanometers of consistency) you can't possibly control what's gonna happen when you hit the dye with power. People have been coating things with layers that accurate for years, but being able to do every second of every day on a consistent basis is a real manufacturing challenge.

I suggest you look at a burned disk via AFM to prove this to yourself.

...The basic manufacturing process for DVD is similar to the current process for CD-ROM, with some exceptions. Two injection molders are required to make one DVD, which consists of two bonded 0.6 mm discs. The second additional manufacturing step is hot-melt glue bonding (single layer) or UV bonding (dual layer). For the dual layer design, a semi-reflective layer is also added to allow both information layers to be read from one side of the disc. DVD also uses a high resolution laser beam to write a glass master in addition to incorporation a new semi-reflective layer rather than the standard aluminum layer in CD-ROM.

This internal design provides DVD with the major advantage over CD. To improve the resolution and readability of two distinct layers, the minimum pit length of a single layer DVD is 0.4 micro meters, as compared to 0.83 micro meters for a CD. In addition, the DVD track pitch is reduced to 0.74 micro meters, less than half of CDs 1.6 micro meters. With the number of pits equating to capacity levels, DVDs reduced track pitch and pit size creates four times as many pits as CDs.

...[Boring bit about reading out to in instead of in to out]...

These numerous manufacturing and design differences lead to an expanded step for DVD production -- more extensive quality control. The DVD process requires optimum pit replication because smaller pits spaced closer together are more susceptible to jitter. In addition, the bonding of two discs requires no tilt in either, making the disc itself a more critical component to the production process

I used to try and helpfully correct people in hopes of preserving the original meaning, but I got sick of the blank stares.

Calling DVD "Digital Video Disc" kinda popped up when DVD-video was unleashed on the market. I'm pretty sure it was an unintentional change by the masses because they mostly only knew DVD as a video format (how many people even today have ever used an actual DVD-ROM?). But it was and is considered versatile because it can store not just video, but audio and data also. I couldn't find a useful link to back me up, but here's a link from CD-Info.

Well, I don't have any information on the lifetime of DVDs, but I know I've heard a quote bandied about on /. a lot that Kodak photo CDs supposedly last for 100 years.

. . . with 95% confidence, 95% of the population of KODAK Writable CD Media will have a data lifetime of greater than 217 years if stored in the dark at 25C, 40% Relative Humiditiy . . .

Source can be found here.

Of course, these disks are stored under ideal conditions, but my own personal experience is that CDs, if handled gingerly, can last a long while. Whether you want to blame the media or the user for the typical lifespan of a cd, which is usually quite a bit shy of 100 years, is your perogative.

Burned CDs, and even more CDRWs, have a tendency to break after a while (don't expect a CDRW to hold data more than 1-2 years).

Granted, nobody will no for sure until these things start failing. But since most of us reading this have already had CDR-drives for more than the 1-2 years you estimate, we know you're wrong.

If you keep your disks cool and out of the sun, those CD-Rs should be good for a very long time.

Two copies is always a good idea. Things like rolling chairs, pets/children, spills, careless movers, etc. can all take their toll.

For more info about CD-R longevity try:

http://www.cd-info.com/CDIC/Technology/CD-R/Media/ TDK.html
http://www.cd-info.com/CDIC/Technology/CD-R/Media/ Kodak.html

Or the main page:

http://www.cd-info.com/CDIC/Technology/CD-R/Media/ Longevity.html

Most manufacturers rate their media at 50+ years under normal office conditions, and some of these tests linked above show they are erring on the side of caution.

If you keep your disks cool and out of the sun, those CD-Rs should be good for a very long time.

Two copies is always a good idea. Things like rolling chairs, pets/children, spills, careless movers, etc. can all take their toll.

For more info about CD-R longevity try:

http://www.cd-info.com/CDIC/Technology/CD-R/Media/ TDK.html
http://www.cd-info.com/CDIC/Technology/CD-R/Media/ Kodak.html

Or the main page:

http://www.cd-info.com/CDIC/Technology/CD-R/Media/ Longevity.html

Most manufacturers rate their media at 50+ years under normal office conditions, and some of these tests linked above show they are erring on the side of caution.

If you keep your disks cool and out of the sun, those CD-Rs should be good for a very long time.

Two copies is always a good idea. Things like rolling chairs, pets/children, spills, careless movers, etc. can all take their toll.

For more info about CD-R longevity try:

http://www.cd-info.com/CDIC/Technology/CD-R/Media/ TDK.html
http://www.cd-info.com/CDIC/Technology/CD-R/Media/ Kodak.html

Or the main page:

http://www.cd-info.com/CDIC/Technology/CD-R/Media/ Longevity.html

Most manufacturers rate their media at 50+ years under normal office conditions, and some of these tests linked above show they are erring on the side of caution.

...and as long as you have a permanent archive (burn them to CD-R), I'm not worried about "losing" them.

On physical longevity, here's some info based on testing by the manufacturers:

We predict the lifetime of KODAK Photo CD, and KODAK Writable CD Media with InfoGuard Protection System, under normal storage conditions in an office or home environment, should be 100 years or more.

File format longevity is the real killer, though. I have quite a few 5.25" floppy disks with documents that were created in industry-leading formats in the mid-1980s. I would like to retrieve some of them, but I (a) haven't seen a 5.25" floppy drive in years (b) can't find any software that will read those formats. And that is only 17 years! Do you really trust your family's history to the idea that JPEGs, for example, will still be readable in 2102?

sPh

Actually it's only with unrecorded CDRs that you have to worry about that 5 year span. As long as you treat them well (eg: not stored on a windowsill) you'll do just fine using normal quality CDRs. See:

http://www.cd-info.com/CDIC/Industry/news/media-ch ronology.html
http://www.cdrfaq.org/faq07.html#S7-5

I'd say there's still some concern with just how long they will last, but apparently it'll be more than 5 years.

Digital technology, however, poses new threats and problems as well as new opportunities. Its functionality comes with complexity. Anyone with a compass (or a clear night to view the position of the stars in relation to true north) could theoretically set up or repair a sundial. A digital watch is more useful and accurate for telling time than a sundial, but few people can repair it or even understand how it works. Reading and understanding information in digital form requires equipment and software, which is changing constantly and may not be available within a decade of its introduction. Who today has a punched card reader, a Dectape drive, or a working copy of FORTRAN II? Even newer technology such as 9-track tape is rapidly becoming obsolete. We cannot save the machines if there are no spare parts available, and we cannot save the software if no one is left who knows how to use it.

With the storage evolving so rapidly, one must ask the question whether you'll be able to your present hard disk decades in the future. My personal recommendation is the obvious: to make physical, hard copies of all important data. Although Kodak claims their CDR media lasts 100 years or more, I still wouldn't hesitate to make physical copies, readable by humans rather than computers.

If you are referring to the US News & World Report media longevity comparison, then you should read some of the following:

http://www.cd-info.com/CDIC/Industry/news/media-ch ronology.html
http://www.cd-info.com/CDIC/Technology/CD-R/Media/ Longevity.html

If you are referring to the US News & World Report media longevity comparison, then you should read some of the following:

http://www.cd-info.com/CDIC/Industry/news/media-ch ronology.html
http://www.cd-info.com/CDIC/Technology/CD-R/Media/ Longevity.html

http://www.cd-info.com /CDIC/History/Pioneers/CDPioneers.html.

Sony and Philips, according to that, but there is no detailed information. A japanese company and a dutch company. Not exactly "secretly developed and used by the states for a decade", is it?

All the major CD-R manufacturers claim expected CD-R lives of at least 50 years, although (being manufacturers standing to profit from longevity) their results may be dubious.

The Special Interest Group for CD Applications and Technology has performed a study; after artificial aging, 3 (TDK, Avery-labeled TDK, and Taiyo Yuden) out of 8 CD-R manufacturers' discs could not be read. There are some limitations to this study, though. There were not enough discs to subject them to the full "Life Expectancy of Compact Discs (CD-ROM) -- Method for Estimating, Based on Effects of Temperature and Relative Humidity" (ANSI/NAPM IT9.21-1996), so there is not estimate of how long these discs are expected to last (which almost makes the aging section of the study useless). The aging conditions were 80C, 85% relative humidity, 750 hour period, ramping rate of half that of ANSI IT9.21 recommendations, and equilibration time of twice that of ANSI IT9.21 recommendations. There are some other links at http://www.cd-info .com/CDIC/Technology/CD-R/Media/Longevity.html that you may want to take a look at.

In my own personal experience, though, I have made about 40 (TDK) CD-Rs that receive heavy use that are about a year old, with no reported problems. Taking life expectancy to mean the average life span of a CD-R...

"Proof" by reduction to an absurdity that the life expectancy of a TDK CD-R is greater than 10 years.

If the life expectancy of a CD-R were less than 10 years, then (As x goes from 0 to (infinity), Integral(2^(-x/h))dx = 10, so h/ln(2) = 10) the half-life of a CD-R would be less than 10 * ln(2), or 6.9 years. Then, the probability of decay after t years would be less than than 2^(-t/6.9). So, the probability of a CD-R surviving one year is less than 2^(-1/6.9), or 0.90. Hence, the probability of 40 CD-Rs all surviving a full year is less than 0.90^40, or 0.018. This is approximately (within 1.1%) the probability of drawing the Ace of Spades from a deck of cards with jokers: possible, but unlikely. Since all 40 CD-Rs did survive a full year, it is much more probable that the original assumption was false (or my math is wrong :-); i.e., it is much more probable that the life expectancy of a TDK CD-R is greater than 10 years.

Now back to studying for my English midterm... :-)
Daniel J. Peng

TDK tests have estimated 70 years for their CD-Rs, Pioneer CD-Rs are rated at 100 years, while this independent site states that life expectancies range from 75 - 200 years based on the color of the disk (green (cyanine) disks last up to 75 years, gold (phthalocyanine) last up to 100 years and platinum last up to 200 years).

On pioneer's site they have DVD-R's for sale and describe them as having 100 year life expectancy.

CD-R longevity reports CD-ROM's (the stamped ones) will last basically as long as you want them too, IIRC. CD-R's (the dye based cd-rom workalike) is claimed to have about 95% reliability at 75-100 years, depending on the brand if stored in a dark place at about room tempature (25c, about 75F). CD-RW's are worse, from what I've heard, but this is mearly hearsay.. Also to keep in mind, if you keep you disks in a light place, a humid place, or in a hotter place, the disk life would be much much shorter. Check out Kodak's permanance page for more info on how temperature, light, and humidity affect CD-R's. There is other good info in their other sections you can reach from this page too. However, in 10 years you will probably consolidate your collection onto a whole lot less of whatever format we have to replace DVD-Rs (or on high capacity DVD-Rs for that matter..), so reliability beyond that is not really an issue. At worst, if you plan on recopying every 35 years or so(1/3 to 1/2 the claimed reliable shelf life), you should have no problems. (BTW, all info for this post was found by doing a search for "cd-r permanence" at www.google.com. A little searching goes a long way ;-)