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Burned CDs Last 5 years Max -- Use Tape?
Lam1969 writes "Computerworld has interviewed Kurt Gerecke, an IBM storage expert and physicist who claims burned CDs only have a two to five-year lifespan, depending on the quality of the CD. From the article: "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." Gerecke recommends magnetic tapes to store pictures, videos and songs."
I have some CDs that are burned copies (although I'd call this great quality cds, not cheap storebrand with no backing), stored in a CD wallet case that are easily over 5 years old... still work great.
Starmen.net
The wedding photographer for my wedding gave me a DVD of the video + photos. After about two years the DVDs were so degraded that I could not a single DVD player would recognize them. And that's with light usage... Now I keep important DVD as images on an external hard disk.
When I first asked this question of how long CDs will last, I was told about 70 years.
I was also told that to lengthen a CDs shelf life, always store them vertically in a cool dry place, and clean them from the inside ring to the outer edge in a straight line.
I found an article from the Optical Storage Technology Association and they say it depends on the initial CD quality and handling.
According to this article, unrecorded CDRs last about 5-10 years, manufacturers claim recorded CDRs 50-200 years and recorded CDRWs 20-100 years.
More info: http://www.osta.org/technology/cdqa13.htm
He who knows best knows how little he knows. - Thomas Jefferson
I can't remember all of the details, but I am sure there was a Dutch group who took a sample of all of the available CDs at the time, burnt data onto them, put them in storage for 2 years and then re-tested the disks quality. Their results showed that all of the disks had significant degredation.
.. here is a link to a news report of that study
OK
http://www.cdfreaks.com/news/7751 This link includes a link to the original Dutch article
To quote:
"The tests showed that a number of CD-Rs had become completely unreadable while others could only be read back partially. Data that was recorded 20 months ago had become unreadable. These included discs of well known and lesser known manufacturers."
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This guy has one. There's even a few pics linked at the bottom of the page. Perhaps he'll let you borrow it.
Be a real patriot: Question authority. Think for yourself. Formulate your own conclusions.
NIST Did a study that shows up to 30+ years of longevity that is totally dependant on handling and storage.
Finally, some have claimed that the glue on the sticky labels might affect the longevity of the dye in the disc, presumably by leaching through the thin top coating of polymer. Search for "glue" in that story, it's half way down or so.
I have CDs that have lasted 10 years with no errors. Obviously 5 years is not the maximum life. Perhaps the maximum EXPECTED life.
I've had CDs that were about 5 years old that went bad. They went from the burner to a CD book, and maybe 2 to 5 out of about 100 were bad. I didn't investigate, or maybe even screwed up the burn (win2k), and I used good media, mostly Mitsui.
I believe the tape recommendation to be absurd. If CDs are in the though process, there must not be too much data here. Especially in the context of movies and music. An external harddrive is much cheaper and easier to use than a tape. Depending on your data needs, they can be as little as $80 or so. Drives are easy to navigate and do a restore. Tapes are a PITA.
Now, at work with terabytes of data, tapes in a robot are worth it. Hopefully, I will never have to do a restore, but I have the backup there in case of the need.
My comments are not for "enterprise" type of stuff. More towards a budget minded and low impact if loss data set. I don't consider movies and music that earth shattering if lost.
I have always viewed any burnable optical disc as a short-term disposable item - I never seriously considered them as a safe medium for long-term archival storage. Up to the recent past, I would have agreeed with the recommendation that magnetic tape is a better long-term medium....but then I ran into the problem of trying to make an ancient tape drive work. These days, I use good old-fashioned IDE (PATA) hard drives in external IDE-to-USB2/FireWire enclosures for archival storage. The problem of the bearings wearing out doesn't happen if the drive isn't on. As long as it's stored in appropriate environmental conditions - it'll last > 100 years. I have a couple of them that I rotate offsite every two weeks, so one copy is at home and another is at the office. Simple, cheap and very reliable.
... I like to keep an open mind, but not so open that my brains fall out. - Judge Harry Stone, Night Court
Ok, here's a sample:Vembu's StoreGrid.
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when they first gave us CD burners *all* blanks used gold for the reflective layer, this isn't new. They used gold for a reason, but this reason escapes me now. One would guess that it had something to do with gold's resistance to oxidizing. I remember being quite surprised when I first saw blanks that did *not* use gold as the reflective layer, and very quickly avoided them like the plague as they coastered like mad. Yeah, that's a verb, honest.
10 years ago, the CDs you were burning were of higher quality, were burned at a slower speed (probably 1x, 2x, or at max 4x), and the burning drive you were using was of a higher quality. You were using high-end equipment and media. Those CDs survived.
I bet that a consumer-grade CD burned last year on a consumer-grade drive purchased last year would not last as long.
Computers are useless. They can only give you answers.
-- Pablo Picasso
were cd burners available back in 1995/6?
There have been CD burners available since the late 1980s
My blog
I have never had a failure on one of my archive disks going back to 1997. But I keep these in individual cases stored vertically etc...
Stuff that is not replacable (my personal photos) I burn on two different disk types. I always use high quality disks. Using Fuji TY dvd R+ right now. I believe DVD R disks are a bit more rugged than CD R.
My car disks live in my car in Ottawa Canada. Brutal humid hot summers, I have a set of CD-r in a visor holder. Most of these disks have been in the car for 5 straight years. When I park a disk in my player it often stays for a week at a time. My CD player ejects disks so hot you don't want to touch them. Here I have a few skippers, but each one that skips is also skratched to pieces. Either way. 5 years of torture and most are still fine. I don't think any skip that are not scratched up.
I feel pretty secure about my well cared for indoor disks lasting ten years. Though I will start moving my CD-R backups to DVD.
In ten years, terrabyte storage should be common and cheap.
There's a correct procedure to follow, so that CDs can be used for long time storage. CDs can be successfully used to store data, even though they're so fragile. It's just necessary to do a lot of maintenance. Don't ask me about the details, I'm just writing here what I remember about this.
:= CD2 and CD2 := CD3.
1) Burn 2 identical CD-Rs
2) Store them inside some protected place, upright
3) When it's necessary to use them, use just CD1. CD2 is never used.
4) After n years, throw away CD1. (Since the guy said it takes 5 years for the CD to stop working, n should be 2.5 or less, depending on how much you use CD1). Burn CD3. Let CD1
5) Goto 2.
This is a very cheap way to store data.
Gonna do some math here.
We'll assume that one can reliably retrieve data from a sheet of paper at 200 dpi.
At 200 Dpi, with reasonable page margins of 0.5" per side, you have 1500x2000 (2.86M) potential dots. Assume one bit per dot. That's approximately 0.36MB per page per side. Add one line of dots per side for alignment.
Since a page is evenly divisible by 5000 bytes, lets start there. 75 5000 byte blocks per page; each 5000 bytes will include:
64 bit address (8-bytes)
64 bit CRC (8-bytes)
Data (4984 bytes)
Additionally, since paper is (currently) a read-only media, we can preprocess the data using squashfs, thus assume that 4984 bytes is actually holding approximately 4k to 8k of data after compression and filesystem overhead.
(4k to 8k)*75==(300 to 600kB) per page, per side.
Thus, it would take roughly 175,000 pages, printed both sides, to equal a 200Gb hard drive. At 6ppm, which is pretty standard for a cheap laser printer, that would take 20 days to back up, not accounting for paper jams, toner or sleep.
110100 1101000 1101000 1100110 0 1101111 1101000 1100011 1
If they can guarantee 100-year lifespan with a bit of gold then surely the problem with normal discs is over-stated.
The gold is there to replace the aluminum because gold won't oxidize. Kodak used to make similar archival quality discs, I still have a few spindles of them.
The drive doesn't 'burn through' the media at all. The dye is what ensures data clarity, and the dye phase changes - meaning it's either all black in that one spot, or its all not-black.
In other words, if six years from now, something you burned with your 'crap' drive isn't working, it's either cos the dis was of poor quality, or because the drive didn't burn the disc properly - in which case, it wouldn't have worked six minutes after you burned it.
110100 1101000 1101000 1100110 0 1101111 1101000 1100011 1
Besides, tapes have a serious format obsolescence problem, because they're unpopular and there are so many incompatible types. Any optical drive you find at BestBuy right now will read a 20 year-old CD just fine, in fact even today CD is the main format for music and shrinkwrapped software distribution. I'll wager that for each of the last 10 years, the number of CDs manufactured outnumbers all the data tapes ever manufactured (and that includes dozens of incompatible types of tape). I think CDs will be readable for a long, long time to come (relative to a human lifetime and not eons).
This thread also strikes me as funny because I'm in the middle of archiving about 800 VHS tapes to DVD. Many are 15-20 years old, and I've been surprised at how well most of them still work. I wonder if the DVDs will last as long, but I figure it'll be easier to move the data off them since it won't have to be done in real time.
1) Burn 2 copies, store them in physical separate locations.
2) Don't fill the discs to the brim. Only encode about 3.8-4.0GB of MPEG2. Fill the rest of the disc with PAR2 files stored in the VIDEO_TS folder (prefixed with the letter 'z' so they appear on the edges/end of the disc).
I render my DVDs to disc first, add the PAR2 data, then create the ISOs with ImgTool Classic before burning to disc. I make sure that my block size for PAR2 is a multiple of 2048 bytes (CD/DVD sector size).
Even if you can't copy individual files off of the disc, tools like ISO Buster or ddrescue (or dd-rescue) can read the disc back at the sector level. That lets you pull as much information as possible back off of the disc. Assuming you don't have more bad sectors then recovery data, QuickPar (or the open-source commandline tool) can chew on that extracted data and rebuild the files.
I did about 100 VHS tapes a year or two ago. I still have a bunch more to do in the coming year.
Wolde you bothe eate your cake, and have your cake?
Gold reflective layer CD-R's with a stabilized pthalocyanine dye have an expected shelf life of 200 years.
That's 4 times longer than the expected life of an aluminum reflective layer pressed CD.
Education is a better safeguard of liberty than a standing army.
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