Writeable CDs last 2-5 years...

[._kaa]

From Computerworld

(http://computerworld.com/hardwaretopics/storage/story/0,10801,107607,00.html)

:

 

"Although opinions vary on how to preserve data on digital storage

media, such as optical CDs and DVDs, Kurt Gerecke, a physicist and

storage expert at IBM Deutschland GmbH, takes this view: If you want

to avoid having to burn new CDs every few years, use magnetic tapes to

store all your pictures, videos and songs for a lifetime.

 

"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," Gerecke said in an interview this week. "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," Gerecke said. "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, he said, because few vendors use life span as a selling point."

 

You have been warned :-)

[anthony_m1]

<I>Distinguishing high-quality burnable CDs from low-quality discs is difficult, he said, because few vendors use life span as a selling point."</I><P>I would have to agree based on personal experience. When shopping recently, I saw no mention of life span on any of the packaging for CD-R and that to me, is a big factor for digital media storage.

[steve_dawson1]

In my experience hard disks are more reliable than home made CDs, though by no means foolproof; you probably need some kind of a RAID system to be sure. I suppose in time we will all have access to online storage where you rent as much space as you need and it is the vendor's responsibility to look after redundancy, data integrity, archiving/back ups, etc.

[daniel_taylor]

I have 8 year old CD-R's that still read perfectly. In fact, I've only had a couple old CD-R's give me problems of any kind, and when I tried a second reader they copied fine (though I still burned new, just to be safe). So there goes that "professional" opinion.

 

There is certainly junk media out there, but that doesn't mean all CD media is going to expire two years post burn.

[pbryan]

I've got plenty of "whatever was cheapest" CD's that I burned nearly 10 years ago that still work fine... Not that that's conclusive evidence... Although, In my experience, CD burners only last 2 years :(

 

--Paul

[Ed_Ingold]

Kaa (odd, that name rings a bell),

 

Baloney! That's one man's opinion, possibly with an axe to grind. There is ample Arrhenius data to show that CD-R's can last a 100 years or longer. There is a difference between discs - the light green or gold phthalocyanine dye discs being the best and having the highest signal-to-noise ratio. There is a difference between burners too - Plextor being arguably the best, Lite-on the worst (at least of any I've tested).

 

Thermal degradation of discs is virtually a non-issue. The laser brings the dye to a temperature of over 400 degrees F to effect the recording. Phthalocyanine dyes have been around since the 19th century, and were used by the Impressionists.

 

The major cause of data loss is 1) a poor initial recording and 2) mechanical damage to the reflective/dye layer. The first is avoided by using an high-quality recorder and software, and checking the results for data integrity and read-error frequency. The latter is resolved by proper labeling and storage, especially out of direct or indirect sunlight.

 

The cheap, dark green (azo dye) discs at the discount counter simply don't record well - having a low signal-to-noise ratio, poor UV stability and generally high error rates. Error rates are due not only to the dye system, but to the quality of the stamping process.

[scott_eaton]

<I>a physicist and storage expert at <b>IBM</b> Deutschland GmbH, takes this view: If you want to avoid having to burn new CDs every few years, use magnetic tapes to store all your pictures, videos and songs for a lifetime. </i><P>That's funny considering how many times I've had to repair my IBM Ultrium units, and how many terrabytes I've seen of magnetic tapes lost due to errant hardware compression, head misalignments, and other crap exclusive to magnetic storage.

[steve_swinehart]

Magnetic tape...sure. Binders dry out, oxides flake off = dropouts. If the tape doesn't have a backing coat on it you get print through - data goes away. Metallic tapes = print through unless wound forward and stored; then rewound & stored, etc. Got lots of 25 year old tapes with a lot of problems on them. I question his familiarity with long term tape storage.

 

Or, he needs to read the Library of Congress study on CD's in which they have found the gold CD's with phthalocyanine dye to be a stable storage medium.

 

One manufacturer has had accelerated aging tests done on gold foil, phthalocyanine dye CD's for light fastness, humidity, and heat. They show and average lifetime of 100 years, and up to 200 years under proper storage conditions.

 

You have been educated ;-)

[jtk]

Steve's words about gold CDs agree with what I've read on CD/DVD geek sites, which universally laugh at longevity of other types. The big brands (Memorex, TDK et al) contract somebody else to make their CDs, the contracts shift, one never knows who actually made them. The deep discount CDs are allegedly the same as the expensive brands much of the time.

 

One report said minidiscs (current 1G versions) are more archival than CDs. Minidiscs have been abandoned by Sony in the US, but they're reportedly bigger than ever in Japanese market.

 

I shoot film ...pretty good backup :-)

[andrew_sacco]

"Or, he needs to read the Library of Congress study on CD's in which they have found the gold CD's with phthalocyanine dye to be a stable storage mediu"

 

Can anyone recommend gold CD's with the phthalocyanine dye? What brands? Memorex, SONY? I have a Circuit City, OfficeMax, Staples..etc within a stones throw of me. I'm using SONY CD-R's now, but I have to go home and see if they're gold colored (?).

[mendel_leisk]

Maxell 8 speed -R DVD's currently on sale in western Canada are Ritek. They are pure shite at 8 speed, many errors, garbage. Will burn ok at 4 speed, but I would not use them for anything important. I like TY's, had no problems with their 8 speed -R, so far...

[Ed_Ingold]

The best disc a probably made by MAM (formerly Mitsui) with either a silver or gold reflective layer. They have an heavy lacquer coating, so there is no significant difference between longevity of the two metals. MAM uses phthalocyanine dyes exclusively in their CD-R's. You also pay over $.50 each in bulk - which is still a bargain, considering the alternatives.

 

All recordable DVDs use metallized-azo dyes, which by all reports appears to perform well and have a long life (50+ years). Azo does not work well at all in CD-R's - there must be a secret ingredient (it does look a lot different in DVDs). Both CDs and DVDs have a modulating frequency and track information molded into the groove. The blanks are stamped with this information just like a commercial CD/DVD, prior to plating. The biggest short-term problems I've had between manufacturers probably lies in the quality of this stamping.

[beverly m]

And where do you purchase the most trusted CD?

[kelly_flanigan1]

Stick with proven technology. Use Charcoal on cave walls. Use Papyrus. Herman Hollirith's cards are the mainstay here. We are using alot of the new core memory too. In heard that you all are using drum memory, I will wait to see it it pans out :)

[vincent_j_m]

I've been buring CDR's and DVDR's for a few years now. Reports say that good CDR's last significantly longer than DVDR's. Haven't come across any bad CDR's except for a batch of sony's which were spoilt in 2-3 months, and I'm waiting and watching what happens to my DVD media.

[steve_swinehart]

The MAM (Mitsui) CD's used to be sold as Kodak Gold CD's. Mitsui has the patent on the dye. The MAM gold CD's can be purchased through InkJet Art (www.inkjetart.com). The CD's are manufactured in Colorado. Cost is quite reasonable.

[bill_tuthill]

LOL, mag tape. The write-only archiving solution.

 

Gold/phthalocyanine might have the most resistance to fading, but

cyanine is most forgiving for different brands of players. Because archiving involves unknown future hardware (if you care to read it!)

I would lay my bets on cyanine. Fujifilm sells Taiyo-Yuden cyanine

CDRs saying "Make in Japan". Maybe archive on both.

 

We don't know enough about DVD to make pronouncements yet. It doesn't

look good; I've already had plenty of compatibility problems with

various recorders and different types of DVD.

[Ed_Ingold]

Cyanine discs (green) are the most forgiving recording medium, but not as easy to read. Phthalocyanine dyes have a greater signal to noise ratio. Taiyo-Yuden discs are a blend of cyanine and phthalocyanine dyes. They are easier to record than phthalocyanine-only discs, but have about twice the reading error rate (still low).

 

DVD's take a little more care in recording. To start, the data rate for DVD's is 9 times that of a CD. That 8x designation refers to video speed for a DVD, and audio speed for a CD. Don't be surfing the web or using Photoshop when burning a DVD! Secondly, it is important to record at constant linear velocity (CLV) wherein the speed of rotation decreases as the diameter of the track increases. This is a maximum of 6x for DVD-R and 8x for DVD+R. Finally, computer-based DVD reader/recorders will read nearly any format well, but set-top players seem to prefer DVD-R discs. The recording structure varies with the production software, which also affects video compatibility.

[Ed_Ingold]

"And where do you purchase the most trusted CD?"

 

I buy MAM (and Taiyo-Yuden) CDR's through CDW or Polyline Corporation. Both have distribution centers in the Chicago area. I buy case lots, but you can get onesies from CDW.

[bill_tuthill]

Edward, the recorded portion of a cyanine CDR looks blue to my eye.

My audiophile friends say that Taiyo-Yuden CDRs have better sound

quality and skip less than phthalocyanine CDRs. I don't know why

or even it it's true, just reporting.

[Ed_Ingold]

Bill,

 

Cyanine dye discs are dark green, diazo dye for CDR's is dark blue. Azo dye for DVDR's is purple - to my eyes. Taiyo-Yuden are relatively light green or blue-green, but definitely darker than MAM discs.

 

I've used several thousand Taiyo-Yuden discs without difficulty, complaints or returns, but over 10 times as many Mitsui/MAM discs. If your friends are getting any dropouts (except when bumping over railroad tracks), they are doing something wrong or have bad equipment.

 

Digital sound is mostly either perfect or unuseable - otherwise, there's no audible difference between media. Sound is different than data, which has more options for error correction and can repeat the read as often as necessary. Audio data, on the other hand, must stream. With sound, most errors are correctable until they reach a rate of 500-600 per second and inaudible until they approach that limit. A good disk averages less than 6 errors/second.

[hugo_lopes]

Magnetic tapes?????????????? LOL!

Even tough it is true that cheap CDs can last only a couple of years, quality CDs like MAM and TDK can last decades. One word on quality CDs: more important than the brand, it is the factory where they were manufactured that really determines the quality of the final product. Some brands buy from two or three differents factories, so it is important to know where the batch in question was manufactured.