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Storage media lifetimes
This subject has been bounced around on here a number of times and the
consensus has been that we really don't know the practical life for files stored on digital media. The latest issue of "Computer World" (Jan 10, 2006) has a good article on the life or storage media or rather the lack there of. http://www.computerworld.com/blogs/n...om=story_picks I don't know if you can get to it without being registered or not, but the gist of the article is the storage life of "burned" optical media is far, far shorter than has been expected or claimed. Of course Hard drives make poor archival media as well. In the end the best media for corporations was still considered to be magnetic tape, but it takes special storage conditions and areas where it is well protected to be considered long lived, but it is much longer than most optical even if far more prone to failure from external sources. Tape needs to be periodically re tensioned, stored on edge, and protected from contaminants, magnetic fields, and heat. Their requirements to get the maximum life out of tape pretty much puts it beyond the scope of the individual or small business. OTOH, tape still has the potential for the longest life of any archival media other than the original film and paper documents. Optical disks need to be stored on edge, in the dark, and kept away from heat. They should not be written on, nor should they have paper labels stuck on them. which makes it difficult to remember what's on which one. When you have a 1000 or so this might get to be a problem. When you think of the G-forces on a 50X disk I can't imagine putting a paper label on one. The upshot of the article, as has been said many times here, is no media last forever. The surprise was the relatively short lifetimes given for CDs (3 to 5 years) and even tape at 20 to 30 years "under ideal treatment and conditions". This all leads to the requirement for a periodic data migration and adds new meaning to the idea of digitizing the "old family slides". I've been testing some old CDs for quality and what I've found so far shows those of 5 years old to be in good shape (with no detectable degradation) and I've certainly not taken any special precautions with them. Many are also the inexpensive ones that are listed as having short lifetimes. The only failures, which were expected were of the R/W CDs as they are notorious for not being reliable. The problem with testing a lot of CDs this old is the time required as they are slowwww.... compared to today's CDs and DVDs. Then take the old 2X DVDs that are full. You turn the computer loose and go do something else. Now I need to go out to the shop and bring in a hundred or so CDs that are the oldest on hand to see how well they have faired. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com |
#2
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Storage media lifetimes
On Tue, 10 Jan 2006 23:34:44 -0500, Roger wrote:
The latest issue of "Computer World" (Jan 10, 2006) has a good article on the life or storage media or rather the lack there of. http://www.computerworld.com/blogs/n...om=story_picks Roger, you think it's a good article, but it may be a bad article, thriving on fear and lying. I don't know if you can get to it without being registered or not, but I could. the gist of the article is the storage life of "burned" optical media is far, far shorter than has been expected or claimed. If the article says the truth, which it probably doesn't. To give an example, the article says that writing on a CD or sticking a label on it reduces the retention time. However, this is untrue in most cases. The exception is only that you use a sticker with a glue that dissolves the CD or DVD. How a pen would do that is beyond my physical and chemical knowledge. The article states such things, but doesn't even cite any evidence. Hans-Georg -- No mail, please. |
#3
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Storage media lifetimes
Roger, you think it's a good article, but it may be a bad article, thriving on fear and lying. Perhaps, but I'm not so sure. I've had multiple CD-Rs go bad over the years since I've had a burner and I don't place a lot of faith in recordable DVDs either, my most recent catastrophe being when I burned about a 1000 digital pictures to a DVD-R. When I went to read the disc two weeks later, my computer (and 3 others I tried it in) claimed it was unreadable and/or damaged. Fortunately, I still had all the photos on my hard drive. Much is dependent on the brand of recordable CD or DVD you buy as well. I've had entire spindles that aren't worth a damn. I've also had two hard drives meltdown in the last 12 years. This is perhaps the one thing that's kept me from moving all my old film negatives over to a digital storage medium, I just don't know what to trust yet. I guess the only way I'd be able to rest easy for the time being is continue keeping 3 or 4 copies of my digital photos in various places, i.e. friends houses, safety deposit box, buried in the backyard. ;-) |
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Storage media lifetimes
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#5
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Storage media lifetimes
On Wed, 11 Jan 2006 11:54:41 +0100, Hans-Georg Michna
wrote: On Tue, 10 Jan 2006 23:34:44 -0500, Roger wrote: The latest issue of "Computer World" (Jan 10, 2006) has a good article on the life or storage media or rather the lack there of. http://www.computerworld.com/blogs/n...om=story_picks Roger, you think it's a good article, but it may be a bad article, thriving on fear and lying. Which is why I said I was going back through my CDs and DVDs checking quality. I did find one with some failures, BUT it was a rewritable CD and those are noted for not being reliable. I have gone back to the oldest I could find (so far) which is 1998 with no failures or even bad blocks. (so far) Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com I don't know if you can get to it without being registered or not, but I could. the gist of the article is the storage life of "burned" optical media is far, far shorter than has been expected or claimed. If the article says the truth, which it probably doesn't. To give an example, the article says that writing on a CD or sticking a label on it reduces the retention time. However, this is untrue in most cases. The exception is only that you use a sticker with a glue that dissolves the CD or DVD. How a pen would do that is beyond my physical and chemical knowledge. The article states such things, but doesn't even cite any evidence. Hans-Georg |
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Storage media lifetimes
As for CD-Rs going bad, I've had some go bad several months after
initially being readable, others (mostly CD-RWs, which I don't use anymore) have been bad from the moment of burning. The DVD-R in question was initially readable after burning. That's one of first things I do anymore after burning to make sure the data made it to the disc okay. Two weeks later I put it in my computer and the disc was unreadable. This also happened to be the spindle where several of the discs were giving me read problems after initially being readable, so I ****-canned the whole lot (TDK, bought at Costco). |
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Storage media lifetimes
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Storage media lifetimes
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#10
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Storage media lifetimes
wrote in message oups.com... SNIP The DVD-R in question was initially readable after burning. That would only tell you that the data could be read, with an unknown amount of error correction(!) Although an immediate verification failure would be a significant warning towards media incompatibility, if you want to get a bit more assurance you'll need a better tool than simply rereading the file. On recorders that report it, the amount of error detection and correction can be obtained with a software tool. The relative amount, and severity, of the errors detected will indicate the suitability of the media for the specific recorder at a specific writing speed. It will then over time indicate the deterioration rate, and provide a warning for imminent (even if not show-stopping yet at the moment) disasters. For a simple test application you could use http://www.cdspeed2000.com/go.php3?link=download.html Variations in read speed are a first indication of trouble ahead, and reports of C1/C2 errors give better/quantifiable clues. "Plextor" recorders (don't know if that applies to all models) come with a PlexTools Pro application that allows to do more in depth testing. They also list compatibility of media with their drive models at http://www.plextor.be/technicalservices/technology/cdrmedia.asp?choice=Supported%20media .. That will allow to have an initial, and ultimately a final warning, tool before having to resort to data recovery tools such as e.g. http://www.smart-projects.net/isobuster/ and http://www.infinadyne.com/cddvd_diagnostic.html. Bart |
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