CD Roms Longevity

The simple answer to that seems to be 'no-one knows for certain'. I've read

Dave

Apples to oranges. Factory discs are not burned, they are pressed (i.e., molded) in the desired pattern. Writeable discs use dyes which are fixed by the laser light to store the pattern. Hence, pressed CD's don't generally degrade from subsequent exposure to the wrong kinds of light as do burned discs. Extending the topic a little to DVD's, there is an unfortunate phenomenon known as "rotting" which occurs even on factory discs. This happens when defective bonding leads to layer separation.

It varies. Assuming identical storage solutions, the main difference is in brands used. But even that's hotly debated. You'll find users of the cheapest crap on the planet proudly proclaiming their discs have lasted 5+ years, while others wouldn't touch them with a ten foot pole. Brand loyalty comes into play as well. If you loved your old verbatim floppies, you might want to stick with verbatim CD's, etc. I personally buy name brand cakeboxes that offer the best value at that time. Usually, they end up being TDK and Maxell, both of which have produced very good magnetic media over the years and I have no prob trusting either company's CD's.

As a general rule of thumb with optical media, you should back up the most precious data at least once a year. That includes DVD's. Data you can afford to lose might get backed up once every few years. There's enough evidence to clearly indicate the hype when writeable optical discs first came out was utterly bogus. Your recording will last a hundred years!!?? Pretty funny.

This is certainly true. I think the cool storage is fine but it should also be dry. Dark probably doesn't matter that much as long as there isn't much UV.

--- sam | Sci.Electronics.Repair FAQ:

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One thing i learned recently about optical disks disturbed me. I had always taken the most care to protect the data side of the disk. I found out that the most fragile side is actually the one with the label. It's the one closest to the actual media. A scratch there--one which might not even glitch a reader if it were on the other side--can expose the metallic layer to corrosion.

jak

Yeah, and a piece of sticky tape may pull it off entirely on CD-R/RWs! :(

--- sam | Sci.Electronics.Repair FAQ:

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That's why I've never used CD-labels. I used to label my CDs directly with permanent OHP pens, but now I use specialized CD pens. (I think the price is about the same these days.)

Hmmm, that sounds like the voice of experience!

Adam -

I would think that a CD label would be a GOOD thing, as long as you don't pull it off (and why would you?). It would be a barrier against the inadvertent scratches that happen during handling. Yes? No? It would also tend to keep ambient light out of the disk - or at least the side that is normally stored upward, facing the light.

Bill =============================

Adam Funk wrote:

Sam -

Some of us don't have the advantage of a dry climate. Here in Arizona things are usually quite dry, for example. But I have half of my DVDs stored on the coast in Maine, where it is quite humid at least 9 months of the year. I assume it would be helpful to put my DVDs in some sort of waterproof box - even a big Tupperware box - and toss in a couple of the "Do Not Eat" silica gel packets that come in bags of rice crackers and other crispy foods?

Bill

The adhesive on labels contains solvents which may compromise the CD's coating over time, or even break it down altogether. I personally would never attach anything sticky to my CDs or DVDs, least of all my most precious and irreplaceable ones.

Dave

Sure. I'm not sure how much it matters but the metallic film is very thin and may not be totally protected if the overcoat on the label side has pinholes, which are quite possible.

--- sam | Sci.Electronics.Repair FAQ:

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I've been under the impression that the adhesives damage the coating. (I could be wrong.)

It's possible. Some solvents will make the coating literally peel off on its own.

--- sam | Sci.Electronics.Repair FAQ:

Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs.

Labels aren't permanent and can cause a variety of problems; among the ones I've seen are causing jamming in slot-loading machines, and clamping problems in regular tray or carousel models. On a regular machine, if any adhesive migrates a bit, the disc can stick to the clamper and also cause jamming problems.

Mark Z.

Thanks, Dave. Didn't know that.

Bill

Thanks. I'll keep using the CD pens.

On Fri, 17 Mar 2006 20:58:18 GMT, snipped-for-privacy@verizon.net (Brad) put finger to keyboard and composed:

Is that for the Windows platform? If so, doesn't Windows' built-in "Find Files and Folders" function do the same thing?

Otherwise, try this from a DOS prompt:

echo f | xcopy d:\ nul /c /h /s > %temp%.\readtest.txt

This reads every file on the CD-ROM (drive D:) and copies it to the NUL device, ie into the bit bucket. The results of each read are recorded in readtest.txt.

- Franc Zabkar

Fortunately, the disks had a rhino hide coating on them that allowed the label to be soaked off. I've stopped using labels since. I just don't trust them to stick properly!

To the poster talking of "Finder", running a program to read all the data is one way of knowing that it's TOO LATE for some of your data.

However, you can get an early warning of impending failure by using a PROPER utility like Nero CD-Speed. This will run over the disk and show you a count of C1 and C2 errors. On most disks you get a handful of C1 errors (low level) over the disk. And maybe a C2 error or two. These aren't a problem. If you scan a disk and get hundreds of C1 errors, or handfuls of C2 errors, then your disk is on the way out. Copy it ASAP. You get a feel for what is "normal" after running CDROMS, CD-Rs etc. through the drive. A really bad "C-GRADE NONAME CDR" will look like the side of a mountain, as the C1 error count starts off and ramps into the THOUSANDS.

This scan is done BEFORE you get to the state of data corruption where the OS is sitting there saying "File error". Error correction is a wonderful thing, but could be hiding the fact that your data is g=tting v ry fl ky ind%!d.

Mike.

I've seen a set of CDs "helpfully" labelled with 3-M PostIts[tm] to aid identification: "This CD Works" "This didn't boot" etc.

After removal of the PostIt, most of them could be labelled with "This Is Now Scrap" "Another Coaster" "Look At The Cool Blue Window In This CD" as it pulled the metallisation right off.

This is not normal for CD-Rs, however, somebody forgot to lacquer coat the shiny side of the disks, and that would be why they were so cheap. Penny pinching purchasing department strikes again.