Personal computing discussed

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Unteroffizier
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Data lifespan in storage media

Sun Jan 25, 2004 8:37 am

Hi all,

just wondering what is the average lifespan of data stored in media - be it CDr, CDrw, DVDr, thumbdrives, memory sticks, external HDD (USB and/or IEEE1394 firewire), floppy etc.

i.e if i save some data (photos, movies, spreadsheets etc) onto the media and leave them as they are, how long can the data last to be read?
 
newbie_of_jan0502
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Sun Jan 25, 2004 8:47 am

I read this link

http://www.zdnet.com.au/reviews/compute ... 043,00.htm

It looks like dvd r is your best bet.
CD-ROM, CD-R, DVD-ROM and DVD-R are popular optical storage media but their durability varies due to difference in their protective coating--CD-R's tend to have a shorter lifespan of ten years while the denser, more expensive DVD usually last anywhere from 70 to a 100 years due to the high quality of their dye coat.
 
just brew it!
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Mon Jan 26, 2004 12:52 am

Interesting... I had noticed that the protective layer does seem to be much thicker in DVDs... i.e. the data layer appears to be approximately in the middle of the "sandwich", instead of just beneath the upper surface.

I do question some of the numbers given in the article, however. It doesn't make much sense to me that Zip discs would have much shorter lifespan than magnetic tape, since the physical media is essentially the same (it is just a matter of whether it is round and flat, or long, skinny, and wound on a spool). And saying that a DVD-R will last for 100 years is little more than an educated guess, since they've only been around for ~4 years!

I think a much more important consideration may be, will you still be able to get devices to read whatever media you've chosen, 25 years from now?
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Kevin
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Mon Jan 26, 2004 12:58 am

That's an excellent point, just brew it! Just think of all those old computer games we can't really play on modern systems because the CPU is too fast or the operating system isn't similiar enough to the old system.

I would hope by now that people storing important information would know enough to continually update their backups to "new" media once that media becomes popular. You'd hate to lose some important data just because nobody makes a certain part needed to repair your outdated storage system.
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Honor
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Mon Jan 26, 2004 1:43 am

Maybe the best bet would be to just keep upgrading to better storage.

So right now store your stuff on CDs or DVD-Rs and in 5 years the new blue laser stuff will be dirt cheap. Then you can move your archives to that media (20-30 CDs on 1 disc!) and in another 5 years there will be some other cool storage medium to move to. That would solve most issues with media decay and all issues with reading old formats (does anyone still sell 5.25" floppy drives?)

Would CD-Rs decay if they were stored in a vacuum? Would be useful if you go to prison or into a coma or if you need to bury it somewhere.
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newbie_of_jan0502
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Mon Jan 26, 2004 6:05 am

In the article they note that a hard drive isn't a good choice. But what about a HD that you move all your data to, uplug it, box it up and store it in a closet. How long would you have now? Heck you can get new 80 gig HD's for 60 bucks.
 
just brew it!
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Mon Jan 26, 2004 9:49 am

newbie_of_jan0502 wrote:
In the article they note that a hard drive isn't a good choice. But what about a HD that you move all your data to, uplug it, box it up and store it in a closet. How long would you have now? Heck you can get new 80 gig HD's for 60 bucks.

Yeah, I actually thought about doing this to archive my CD collection. I eventually opted for DVD+R instead because the cost/GB is still lower than hard drives, I needed a DVD burner anyway, and DVDs should be more durable/stable than a hard drive.
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slymaster
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Mon Jan 26, 2004 10:59 am

I don't think I have witnessed a CD-R go bad due to age yet.

The other day, I spilled a cup of boiling water on an important CD-R (I have more than one copy, but not on-site). Luckily, the CD-R survived the experience. I made another copy right away. CD-R's can certainly take more abuse than a hard drive !
 
atidriverssuck
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Mon Jan 26, 2004 11:23 am

slymaster wrote:
CD-R's can certainly take more abuse than a hard drive !


yep, but not scratching the label surface and storing sensibly is important. I think optical media (CD/DVD) rule, overall. I have far more faith in half-decent optical media than HDs. Which isn't saying much, really :) HDs to me are pretty low on the reliability scale.
 
morphine
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Mon Jan 26, 2004 3:54 pm

Tapes still rule for price/GB. They require a large initial investment for the drive, though. And DVD-Rs, though being as good as they are, only take 4.7GB (and soon twice as that with 2 layers).

On another note, the only CDs that I had "dying of age" were some crappy non-branded ones that started peeling off after just a few months. My first CD-Rs, from the time when they cost $10+ a piece, are still alive and kicking. CD-R manufacturing quality definitely came down with time, as they grew more popular and corners started to be cut.
 
FroBozz_Inc
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Mon Jan 26, 2004 4:15 pm

morphine wrote:
Tapes still rule for price/GB. They require a large initial investment for the drive, though. And DVD-Rs, though being as good as they are, only take 4.7GB (and soon twice as that with 2 layers).

On another note, the only CDs that I had "dying of age" were some crappy non-branded ones that started peeling off after just a few months. My first CD-Rs, from the time when they cost $10+ a piece, are still alive and kicking. CD-R manufacturing quality definitely came down with time, as they grew more popular and corners started to be cut.


I agree with that statement.
I remember when most CD-r's seemed to have a layer of actual gold in them. I used to have the best luck with those that had gold or 'gold-on-gold' constuction. I hate the cheap disks you can buy now, you hold them up to the light and you can see through them. That doesn't instill confidence in their robustness. I wonder if some of these archival times were based on the old (gold?) disks or there cheap modern-day knockoffs.
 
Unteroffizier
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Mon Feb 09, 2004 8:45 am

Will there be any warning or tell-tale signs of your storage media breaking up or breathing its last?e.g HDD (IDE/ SATA) and external HDD.

Currently i am backing up all the stuffs from my PCs and notebook onto a separate portable HDD and is thinking of getting an IDE DVD-burner and DVD-r medias as an additional back up instead of a newer and bigger storage external portable HDD. Comments anyone? Can i save whatever i have (images, MPEG files, data files etc) all in DVD format on DVD-rs?

that is......

Should i get a bigger capacity external HDD or.......
Should i get a high-end DVD-burner and DVD-r medias?
 
just brew it!
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Mon Feb 09, 2004 9:16 am

DVDs should be much more durable than an external hard drive. Drop the hard drive once, and all of the stuff you backed up is toast. Drop a DVD, and unless you happen to be particularly unlucky (e.g. drop it edgewise onto a concrete floor), it should survive.

DVD-R/DVD+R can be used just like a big CD-R. I use Nero to back stuff up to DVD+R discs.
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Unteroffizier
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Mon Feb 16, 2004 9:11 am

morphine wrote:
Tapes still rule for price/GB. They require a large initial investment for the drive, though. And DVD-Rs, though being as good as they are, only take 4.7GB (and soon twice as that with 2 layers).

On another note, the only CDs that I had "dying of age" were some crappy non-branded ones that started peeling off after just a few months. My first CD-Rs, from the time when they cost $10+ a piece, are still alive and kicking. CD-R manufacturing quality definitely came down with time, as they grew more popular and corners started to be cut.


I have had experiences with bad CD-rs in the past. Data just went unreadable in less than a year after burned. No doubt the choice of the right media is important.

What are your views of the dye and material used on CD-rs for consumers? What are the difference in theirs manufacture and material used as compared to the CD albums that we see in music/ movies stores?
 
just brew it!
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Mon Feb 16, 2004 10:38 am

Unteroffizier wrote:
I have had experiences with bad CD-rs in the past. Data just went unreadable in less than a year after burned. No doubt the choice of the right media is important.

Sticking to name-brand media is a good idea if you value your data.

I have also read that certain types of permanent marker and adhesive CD labels can be problematic. The ink from the marker or the adhesive on the back of the label can react with the top coating on certain brands of CD-R, eventually "rotting" it to the point where the data layer is damaged.

Your best bet is to label CDs using a marker that has been specifically designed for writing on CDs. Although FWIW I have never had problems using a plain old "Sharpie" permanent marker either.

What are your views of the dye and material used on CD-rs for consumers? What are the difference in theirs manufacture and material used as compared to the CD albums that we see in music/ movies stores?

CD-Rs are actually completely different technology from commercial audio CDs and CD-ROMs. They just happen to have similar optical properties after they are burned, which allows them to be read just like a commercially pressed disc.

In a commercially pressed disc, the data is encoded in a spiral track containing pre-pressed bumps that encode the digital 1s and 0s. This is then coated with a thin layer of reflective aluminum (so the laser can easily "see" the bumps), and the aluminum is then coated with a layer of protective resin. There is no dye layer in a pre-recorded CD.

In a CD-R, there is still a pre-pressed track, but it contains no data; it only supplies timing information that is used by the burner (this is the "ATIP", or Absolute Time In Pregroove). This is then coated with a layer of dye; on top of the dye there is a layer of reflective material (typically silver alloy or gold); and then the resin topcoat. During the burning process, the laser burns holes in the dye layer to form the pattern of 1s and 0s by selectively exposing the reflective layer.

The type of dye, and the thickness (and composition) of the resin topcoat can both vary on CD-Rs. AFAIK current dyes all have pretty decent projected lifetimes. The topcoat can be very thin on cheap/generic media though; I've seen cheap CD-Rs where you could literally flake the coating off with your fingernail!

The proprietary dark blue dye used in Verbatim's "DataLife Plus" line of CD-Rs supposedly has a longer lifetime than most other dyes; the DataLife Plus discs also have an extra thick topcoat, which should make them more durable. They cost a little more, but may be worth the extra expense for stuff you plan to keep for a long time.
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morphine
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Mon Feb 16, 2004 12:06 pm

Well, JBI has covered pretty much anything I could say... :D

I'd like to add that a top protective layer (on the opposite of the reading side) is a really good idea, because you can easily damage the topside with the slightest scratch, tearing off a bit and leaving the CD in an unreadable state.

So when picking media, pick a branded one first, especially one with 1+ top coating layers. However, don't fall for marketing (i.e. "For super-lifetime storage!!!", experience is your only friend here. And _NEVER_ use stickers on the CDs. Those will react/tear off the surface. Stick to markers.
 
just brew it!
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Mon Feb 16, 2004 12:21 pm

Also, here's a site with more than you could ever want to know about CD-R technology: http://www.cdrfaq.org/
Nostalgia isn't what it used to be.
 
henry44
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Mon Feb 16, 2004 12:40 pm

HD's, after a period of inactivity, have a tendency to not spin-up. The disc lube sort of welds the head to the parking lot. This makes HD's for long term storage less than the optimum choice.

In terms of cost per gb, DVDs and tape are the best bet, tape having the larger initial cost. On the other hand, 400gb per tape is possible, so storage of storage medium is less of a problem.

If you are doing daily or hourly backups of changed files, tape is the way to go. If you are doing monthly or archival backups with less than, say 25gb, DVDr might the medium of choice.

I, personally, use a scsi DLT tape drive with a 40gb capacity and do a daily changed file backup with a complete backup once a week. The equipment came from e-bay and cost me about $50.00 for the drive and 3 tapes.

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