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Up To 10% of CD-Rs Fail Within a Few Years

kdawson posted about 5 years ago | from the nothing-lasts-forever-mister-bond dept.

Media 317

Whatever you think about the likelihood that a new kind of DVDs could last for 1,000 years, this note from reader crazyeyes should give you pause about expecting current CD-Rs to be reliably readable for decades. TechARP found a failure rate near 10% for CD-Rs recorded 7 to 9 years ago, after storage in ideal conditions. On some, one or more individual files could not be recovered; others were not reliably readable on two separate drives. "In the past, hard disk drives were small (in capacity) and costly. To make up for the lack of affordable storage, many turned to CD-Rs. As it became common to store backups and personal pictures, videos, etc. on CD-Rs, the lifespan of these discs became a concern. According to manufacturers, CD-Rs should last for decades. Some even quoted an upper limit of 120 years based on accelerated aging tests! That sure is a long time, isn't it? But will CD-Rs really last that long?"

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317 comments

Jews (-1, Offtopic)

Anonymous Coward | about 5 years ago | (#28751417)

I blame them.

TUCKER LOSES A FILM REEL HILARITY ENSUES (-1, Offtopic)

Anonymous Coward | about 5 years ago | (#28751425)

(After one of the film reels gets damaged and Tucker can't get a replacement reel in time, he tells a sold out San Diego crowd the following)

"Okay, check this shit out. The average film is spooled on like six separate film reels and shit. About twenty minutes each, give or take; I'm not a fucking projectionist. Well last night after leaving Arizona, which is a cool place but hot as shit, and those fucker don't party like you fuckers in SD!"

CHEERS FROM CROWD

"Anyways, last night the fifth reel of the film got destroyed. But here's the funny part. I FUCKING DESTROYED IT. Well, not me, but a motherfucking Tiger."

CROWD GOES NUTS

"Serious, this is true story. Last night we got to SD early, like 2:30am. The whole way here Nils, Dawes, Tando and I were doing shots of moonshine. Like 40 or 50 shots each. We're full-on buzzed and looking for some fun. Then I remember there's a Naval base down here in SD. Holy shit, I said 'I should call up a few Navy SEAL friends I know.' BAD. IDEA."

CROWD LAUGHS

"By 3:00am my SEAL buddies BroHawk, Mondo and Terror meet us in a parking lot. They didn't come empty handed. They brought a Howitzer machine gun. If you're not familiar with the power of a Howitzer let me explain. Ten seconds of rapid fire from a fucking Howitzer can turn an entire Iraqi Wedding party into two thousand pounds of ground beef and shit."

CROWD ERUPTS WITH EXPLOSIVE APPLAUSE, A FEW BOOS

"Calm the fuck down, they're Iraqis NOT humans"

GUYS IN TANK TOPS AND FLIP FLOPS ARE NOW ROLLING IN THE AISLES

"Fuck, I haven't even told you motherfuckers the best part of the story. Shit. so we spent the next hour drinking beers and shooting out every motherfucking street lamp in a two mile radius. The cops were called and we took off in the tour bus. Since I was fairly drunk I knew the best thing for me to do was, well, drive the mother fucking bus!"

CROWD JUMPS UP AND DOWN WITH HOOTS

"Problem is, I couldn't figure out how to work the fucking air conditioner. So now it's like 100 degrees in the tour bus and I'm doing like 80-90 mph. To where? Who the fuck knows? Anyways, since everyone is sweating and shit, people started taking off their shirts and shit. I look in the mirror and I catch my Navy SEAL buddy Terror's reflection. He is shirtless, sweating and cut like a motherfucker. Full on six pack, nice round pecks, shoulders to die for."

GIRLS IN THE CROWD SQEAL

"At this point I'm no longer looking at the road. I'm looking at Terror's fucking chest and thinking about running back there and sucking and licking his nipples. Damn, dude has a better body than me motherfucker."

CROWD GOES SILENT

"Shit. I don't have notes. Where the fuck was I again?"

GUY IN CROWD "YOU WERE ABOUT TO GO GAY"

"Gay? Motherfucker, I've pleased more pussy than Purina Cat Chow!"

THE CROWD EXPLODES WITH LAUGHTER

"So I'm driving the fucking bus down the road when I see a sign. A sign from God. It reads: SAN DIEGO ZOO. 'Guess where we're going motherfuckers' I yelled to the boys. So a few minutes later we're in the zoo parking lot. Obviously it's closed. Closed to the public that is, but not Tucker Fucking Max!"

STANDING OVATION WITH TWO MINUTES OF APPLAUSE

"So I pull the fucking bus into the zoo's parking lot. The bus has all these fucking gears and I'm just beating the shit out of the engine. Since we were Tucker Max drunk at that point I decided to park the bus across 15 handicap spots. Who the fuck brings retards to a zoo anyway? (mocks retard voice) 'I wannaz dee munkeee!!!!"

THE CROWD ROLLS WITH LAUGHTER

"Fuck. Note to self. San Diego is full of sick motherfuckers!"

THE CROWD CLAPS AND STOMPS FEET

"Hold on, you're going make me lose my place. Ok, right, so we're fucking in the parking lot of the San Diego zoo at 3am. We get off the bus to stretch our legs and I look over at Nils. He is in shock and pointing at something. Was he looking at a copy of USA today announcing Pizza Hut Chapter 11? Who the fuck knows. So I turn around to see what the fuck and there underneath the bus are a set of legs. Holy shit, I fucking ran over somebody. Not HIT someone. Not drove NEAR someone. But actually fucking DROVE OVER THEM WITH A 8000 POUND TOUR BUS!"

THE CROWD LAUGHS

"I went over and started kicking the legs and shit. Nothing. Finally Terror and Mondo went over and dragged the body our from under the bus by its feet. Holy shit. It's like a fifteen year old kid. I almost felt bad. He was toast."

THE CROWD SIGHS, AWWWWW

"Hold your awwwws you fucking pussies. The kid was Mexican!"

THE CROWD EXPLODES WITH RELIEF LAUGHTER

"Terror looked down at the body and says; swear to God, he says 'Looks like someone was trying to steal your axle, Max!' I fell to the ground laughing, tears rolling down my face. After a few minutes we tried to collect our thoughts. Being Green Berets and shit Terror, BroHawk and Mondo did the only natural thing they are trained to do in these situations. They took camera-phone pictures of themselves resting their nutsacks across the dead kid's forehead. It was a fucking Kodak moment."

THE CROWD BELLY LAUGHS

"You should see the photos. Fuck. I'll try to get them on the blog tomorrow or some shit. Terror has perfect fucking nuts, man, shit. Like two hardboiled eggs wrapped in fucking panty hose."

THE CROWD MURMURS

"What? I'm a stickler for detail and shit."

MORE LAUGHTER

"So now here we are. Drunk and at the zoo. I want to go fuck with some animals but we have a fucking wetback body we need to deal with. I forced Tando and Ryan Holiday to bring it inside the tour bus. Terror and Mondo propped the fucking body in a chair and rigged its jaw with string and tape so that as they watched ESPN playbacks on TIVO they could make the dead Tonk mouth the words. Like I said, I'm not even the coolest one of my friendses."

GUY IN CROWD YELLS "I FUCKING HOPE SO"

"Excuse me; are you a fucking dude or a chick?"

THE CROWD EXPLODES WITH LAUGHS. TWO PARAMEDICS WHEEL IN A STRETCHER JUST IN CASE

"I decided I had enough ESPN and set out for the zoo. As I made my way to the zoo gates I was approached by a security guard. Only it wasn't a security guard, it was a hot chick. She was in her forties with a nice round ass and big tits. She had tears in her eyes. 'Are you like fucking okay and shit?' I said to her. She said 'no.' From her accent and skin color I could tell she was Mexican. I had two obvious choices. Do I fuck her in the pussy of the ass?"

THE CROWD CHANTS "ASS ASS ASS ASS"

"Calm down you SD motherfuckers. Last chick I fucked in the ass was Bob Gosse. ..ahh---oooohhh.."

(Tucker does an Andrew Dice Clay rim shot "ah-ooohhh" but it's so high-pitched that is sounds more like an eleven year old girl's reaction to seeing a spider)

"Then she said the magic words. 'Can you help me find my son?' "

(TO BE CONTINUED)

Re:TUCKER LOSES A FILM REEL HILARITY ENSUES (-1, Offtopic)

Anonymous Coward | about 5 years ago | (#28751539)

Thank you.

According to... (5, Insightful)

NervousNerd (1190935) | about 5 years ago | (#28751435)

According to manufacturers, CD-Rs should last for decades.

According to their marketing dept., rather.

Re:According to... (4, Funny)

goombah99 (560566) | about 5 years ago | (#28751513)

Well you of course have to use an error correcting code. people who don't do that then blame the manufacturer's got what they deserved. For example, personally I get 120 years out of my CDs by encoding 699Megabytes of errorcorretion. this leaves me with 1 byte of data. but it last 120 years.

Re:According to... (2, Insightful)

RiotingPacifist (1228016) | about 5 years ago | (#28751711)

What are you talking about? AFAICT (quick google and wikiread) the only type of error correction you get on CD-Rs is inherent in the format of the disk, so it doesn't cost you any storage space (for data anyway). If you start adding extra layers of ECC (e.g duplicate all files and keep a hash table)then your not dealing with anything CD specific anyway.

Re:According to... (0)

plover (150551) | about 5 years ago | (#28751793)

Woooosh!

Re:According to... (4, Interesting)

Jafafa Hots (580169) | about 5 years ago | (#28751929)

While the GP was just joking, you CAN burn stuff to media with extra error correction of a sort. Burn it as rar files, with a certain percentage of the space devoted to par files. Redundant blocks that way - so if, say, 5% of the files are unreadable, you can reconstruct them. I suppose you could do the same thing across a series of discs, to be able to replace a bad disc.

I do not need nearly that much ecc (1)

daryl_and_daryl (1005065) | about 5 years ago | (#28751817)

i just paint the byte of data on the disk - i just use the drive to spin dry the ink -- faster than trying to burn all that ecc on the disk too

50,000 year retention time (5, Funny)

MillionthMonkey (240664) | about 5 years ago | (#28751977)

Just broadcast your illegal movies and ugly photos toward a large, massive body so that the signals intersect with the earth again later after traveling along space-time geodesics. You can use Sagittarius A* (black hole at the center of the galaxy) for this, but you have to remember to be there to record your 50,000 year old backup once it arrives, because it's not like the hole is your bitch.

Re:According to... (4, Informative)

suso (153703) | about 5 years ago | (#28751529)

Exactly, in my own experience, I started using CD-Rs in 1996. Back in 2007, I spent the time to copy all my old CD-ROMs of value to a hard drive for archival. I found that pretty much all of them were readable, even the 5 or 6 that were from '96. The only one I had problems with was a hybrid audio/data disc that I foolishly wrote in a proprietary format. But 80 or so of the discs that were spread across all the years worked ok. I was actually surprised because I expected some to be unreadable. I do think its great that they are trying to improve the longevity of the discs though, but they should find a solution that doesn't require a special drive.

Re:According to... (4, Insightful)

w0mprat (1317953) | about 5 years ago | (#28751959)

I reccently went back to CD-Rs from the 90s, and didn't really think much of it. I have a stack of about 25%-30% unreadable CD-Rs from less than 5 years old. Interestingly these are mixed brands, some of the buggered ones.

I would suggest as the cost per unit fell through the floor, so did any regard for quality control as well as the consumers lack of motiviation to drive all the way back to the store and get a replacement.

Depends on the brand (5, Interesting)

Goldberg's Pants (139800) | about 5 years ago | (#28751441)

I've experienced this myself lately with a bunch of disks that were now useless. It was cheaper off brand disks that failed. The irony is at the time I got them, they were the ONLY disks I could get to work on my CD player.

So far I've had no failure with CD-R's from Sony, TDK etc... Which were the disks my CD player simply would NOT play.

Re:Depends on the brand (0)

Anonymous Coward | about 5 years ago | (#28751449)

So far I've had no failure with CD-R's from Sony, TDK etc... Which were the disks my CD player simply would NOT play.

Maybe some kind of DRM thing from the major brands, a way to sell their overpriced "CD-R audio" discs.

Re:Depends on the brand (1)

wakingrufus (904726) | about 5 years ago | (#28751569)

more likely he was burning them at a faster speed. old cd readers couldn't read discs if they were burned at faster than like 4x

Re:Depends on the brand (1)

Dullstar (1581331) | about 5 years ago | (#28751847)

I've had a few CD players themselves die. I'm just asking, could it be your player?

It's probably the disks though, because there are several technologies that are less advanced than their manufacturers want you to think.

Re:Depends on the brand (4, Informative)

plover (150551) | about 5 years ago | (#28751885)

By brand, you mean "manufacturer". Most big names, such as Sony, etc., don't make their own disks, but buy them from an external factory and place their own labels on them. The various manufacturers have different chemicals and dyes embedded in their discs, and its that chemical composition that determines the longevity.

Usually the brand will buy discs exclusively from one factory, but some of the off-brands (such as house-branded Office Depot or no-name discs at Micro Center) could be sourced from anywhere, and their quality will vary widely.

Re:Depends on the brand (2, Interesting)

Mashiki (184564) | about 5 years ago | (#28751941)

I have CD-R's from a variety of brands that have failed in the first few years. The discs from my burner back in '99 are dead, I tried those a year or so ago into the trash they went. Personally I'm not sure if it's a problem with the discs in some cases, or the newer drives not following the proper standards. I also have DVD-R's that no longer read, and DVD-RW's

In some cases, I find that the new multi-drives will fail to properly read burned CDRs(much like the days of yesteryear when burning was hitting it's hayday), but regular(if you can find them), CD drives will read them fine.

i have entire 1993 CD-R spindle (5, Interesting)

markringen (1501853) | about 5 years ago | (#28751451)

i have entire 1995 to 1998 CD-R spindle's and all 400 of them still function just fine. i recently had to run trough all 400 of them, and had zero read errors. i guess my discs are possessed by some magical force, or this is just bogus.

Re:i have entire 1993 CD-R spindle (1, Informative)

Anonymous Coward | about 5 years ago | (#28751499)

The earlier burners were expensive and better quality so it's probably more of a burner issue than a disk issue in this case. I've had a lot of disks die after even a few years buy they were burned on consumer level burners. Multiple back ups and later storing on hard drives was my solution. I find the DVDs more stable though because I just yesterday pulled files off an eight year old DVD and they were fine.

Re:i have entire 1993 CD-R spindle (4, Informative)

willy_me (212994) | about 5 years ago | (#28751849)

The earlier burners were expensive and better quality so it's probably more of a burner issue than a disk issue in this case.

Not likely, burners do not affect the aging of disks. It is the dye on the Aluminum that ages and eventually kills the disk - typically a result of oxidization. Cheaper disks use cheaper dyes. The brand name disks are more expensive because they use dyes that are patented - and therefor more expensive to license. The plastic coating that protects the dye from oxidization is also likely to be different on the more expensive disks.

Personally, I've only noticed flaws in the cheap disks - the brand name disks appear to age well. But the cheap disks are still very useful. I use then when distributing files to friends and family - this way I do not have to worry about getting them back.

Re:i have entire 1993 CD-R spindle (0)

Anonymous Coward | about 5 years ago | (#28751511)

Well if their burn date can change depending on whether you write it in the subject or the body, I'd lean toward the magical force explanation.

Re:i have entire 1993 CD-R spindle (1)

Parker Lewis (999165) | about 5 years ago | (#28751533)

At that time, the discs were really well made. Today, all China cheap operations keep the CD manufacturer discs. In that time, CDs was (not so) expensive, today is almost free, with crap material.

Re:i have entire 1995 CD-R spindle (1)

markringen (1501853) | about 5 years ago | (#28751571)

if you pay crap you get crap. i've also never really had an issue with DVD-R's besides their being more brands of burners vs 1995. i think it has more to do with the amount of quality burners vs just the poor quality of media.

Re:i have entire 1995 CD-R spindle (1)

Parker Lewis (999165) | about 5 years ago | (#28751601)

What a bad burner does? Burn a bad bit?

Re:i have entire 1995 CD-R spindle (3, Informative)

pantherace (165052) | about 5 years ago | (#28751717)

There's error correction on CDs, the problem is that a 'bad' burner could produce a disk which is correctable to the proper data, but later on as some material degrades, will become unreadable, as opposed to simply requiring some error correction.

There used to be some brands that the firmware would show stats of that, however there haven't for a number of years, barring a few firmware hacks. (Amusing having to hack the firmware to get information that used to be semi-common.)

Re:i have entire 1995 CD-R spindle (1)

hazem (472289) | about 5 years ago | (#28751823)

What a bad burner does? Burn a bad bit?

The problem is that things in the physical world are rarely binary. Sure, an "on" might be the laser bounces back and an "off" is where the laser passes through. But what's the quality of the holes made and what to their boundaries look like. I'm guessing that the light reflected back is never 100% and the light that goes through is never 0%, but rather there are fuzzy boundaries. If the laser that does the burning doesn't do a good job on the boundaries between 1's and 0's then after some degradation in the material, a reading laser might have trouble figuring out if 50% should be a 1 or 0.

Re:i have entire 1995 CD-R spindle (0)

Anonymous Coward | about 5 years ago | (#28751893)

What it is? Burn a bad bit?

Re:i have entire 1993 CD-R spindle (1)

jzhos (1043516) | about 5 years ago | (#28751547)

How do you know not because of your small sample size happen to fall into those didn't break? A small number of "not happening" does not disapprove "some thing can happen". That is basic logic.

Re:i have entire 1993 CD-R spindle (1)

godrik (1287354) | about 5 years ago | (#28751565)

however, on a set of 400 all of them working means that the 10% rule does not apply to them. (yes, it is statistically significative). It has probably to do with the CD quality or the burner quality or whatever. But it has some sense.

Re:i have entire 1993 CD-R spindle (2, Interesting)

Tablizer (95088) | about 5 years ago | (#28751575)

I'm a little confused on the year. Does the collection start at '93 or '95?

Re:i have entire 1993 CD-R spindle (1, Insightful)

WiiVault (1039946) | about 5 years ago | (#28751585)

How this god modded insightful is beyond me. CD-Rs, especially cheap ones are known to degrade. Heck 10% in 10 years is actually pretty darn good even with decent media. Arguing this isn't true is like saying magnetic media doesn't lose a charge. I'm shocked that all 400 discs worked when even some pre-fabed discs would have failed in that time. If this is for real you must be the luckiest person on the planet. Obviously discs were more likely better made back then too.

Re:i have entire 1993 CD-R spindle (2, Interesting)

djrobxx (1095215) | about 5 years ago | (#28751939)

In 1993 blanks were about $40 a piece. Mighty expensive spindle you got there! My first audio CD-R made in 1995 still works, despite NOT being kept in ideal conditions and being pretty banged up.

doubtful (1)

madcat2c (1292296) | about 5 years ago | (#28751455)

Just look at top of the line storage 30 years ago. Can you even get reliable hardware to try and read it anymore, assuming that the media was any good? Are the file formats from 30 years ago anything that you can use or even really want today?

I would say take the Rosetta Stone approach. Pick at least three types of storage and hope that in the future one would be usable.

Re:doubtful (1)

rbarreira (836272) | about 5 years ago | (#28751509)

Are the file formats from 30 years ago anything that you can use or even really want today?

In many cases, yes. Why wouldn't I want to see the photos from today in thirty years?

Re:doubtful (1)

madcat2c (1292296) | about 5 years ago | (#28751535)

But will you want to look at JPG, or TIFF, or whatever format you use now.

Re:doubtful (1)

Drinking Bleach (975757) | about 5 years ago | (#28751561)

That is a silly question, why wouldn't you?

Did you mean "will you be able to look at the JEPGs, TIFFs, or whatever formats you use now?" -- that question would have been more reasonable, although I don't believe they'll go away any time soon, especially with publicly documented specifications on them. Hell, look in ImageMagick (or to a lesser extent, GIMP), it contains support for several formats long obsolete since the 1980s, but support is maintained within them.

Re:doubtful (1)

rbarreira (836272) | about 5 years ago | (#28751627)

If the photos are in that format, yes. In the worst case I can use an x86 emulator for whatever architecture we use at that time, run windows and view my JPGs.

Given the popularity of x86, I'm sure there will be plenty of emulators.

Re:doubtful (1)

Darkness404 (1287218) | about 5 years ago | (#28751551)

Then you should print them out on decent paper. I've found that recently people take a -ton- more pictures because they are digital and really only a handful of them they -really- want. Yes, all those pictures with you and uncle Bob may be nice, but you don't need 30 instances of it half of them with someone's eyes closed, etc. So really, if you print out all your -good- pictures and just keep backing up with each new system, you should be good. Worst case is you lose all the pictures that were crap.

Re:doubtful (1)

Com2Kid (142006) | about 5 years ago | (#28751807)

I've found that recently people take a -ton- more pictures because they are digital and really only a handful of them they -really- want.

This has always been true with photographs.

You take a 100 pictures, and hope 5 of them turns out good.

There is a reason people used to pack a large number of film rolls when they went on vacation. At 24 pictures per roll, burn through five or six rolls at minimum, and hope you got a few decent pictures out of it. Digital cameras allow people to take even more photos, so at least in theory there is a greater chance of a few high quality pictures coming out on top.

I do agree that archiving all digital photos is silly, the delete key exists for a reason.

Re:doubtful (1)

MightyYar (622222) | about 5 years ago | (#28751937)

I do agree that archiving all digital photos is silly, the delete key exists for a reason.

I'm guilty of this. Thing is, I'm not being anal... actually the opposite - I'm lazy and hard drives are cheap. It would take days to go through all of my old pictures... or I can just wait for my current drive to die and buy the latest quadrillion-teramegabyte drive that's on the market at the time.

Re:doubtful (4, Funny)

sakdoctor (1087155) | about 5 years ago | (#28751553)

I would say take the Rosetta Stone approach.

Good advice. I save three word 97 copies of all my documents. One in English, one in classical Greek, and one in in hieroglyphics.

Re:doubtful (4, Funny)

Anpheus (908711) | about 5 years ago | (#28751765)

I save mine in Arial, Times New Roman and Wingdings.

Is this sufficient?

Re:doubtful (1)

jamstar7 (694492) | about 5 years ago | (#28751681)

Top of the line storage 30 years ago was 8" floppy discs and 9 track tape reels.

Re:doubtful (1)

MightyYar (622222) | about 5 years ago | (#28751903)

Just look at top of the line storage 30 years ago.

Chances are that if you haven't looked at it in 30 years, it wasn't all that important.

I mean, would the ability to read my Apple ][e disks be nostalgic? Yeah. Nostalgic enough that I've felt the need to track down a machine to read them since I got rid of it in the early 90s? No. Everything that was important enough got transferred over when I got a new machine.

Re:doubtful (4, Funny)

plover (150551) | about 5 years ago | (#28752037)

30 years ago I punched my programs on "archival quality" punch cards. They weren't like regular cardboard cards, they had a higher rag content that would assure they'd retain their shape longer with less chance of bending.

Follow the Orange Book (4, Insightful)

La Gris (531858) | about 5 years ago | (#28751465)

120yers, lets start with archive rated CD-R, and use a decent recorder with a tray. Then write according to the orange book specifications.

Were those disks verified? (5, Interesting)

msobkow (48369) | about 5 years ago | (#28751477)

I've had CD-Rs and DVD-Rs that I burned over a decade ago still read fine. However, those disks were verified burns where I immmediately read back the data with Nero to make sure they were ok.

There was a time when I didn't do verified burns. Those disks have a ridiculously high failure rate, but I'm betting they were bad burns in the first place. With most media I get close to a 10% failure rate on verifying the burns.

Re:Were those disks verified? (1)

WiiVault (1039946) | about 5 years ago | (#28751563)

I would say if you are getting 10% failure rate when you verify you are either using really cheap media, have too little ram, or are using an external drive on a congested USB chain. Or maybe its your burner. I use a pretty standard drive, and medium quality (Memorex) media and I would say about 1%-2% of my burns fail to verify and an additional 1% or so fail to burn in the first place.

Re:Were those disks verified? (1)

TavisJohn (961472) | about 5 years ago | (#28751667)

I verify my burns too. However I also burn at slower speeds. For CD-R I do not burn faster than 16x. For DVD-R I do not burn faster than 8x. For DVD-R(DL) I do not burn faster than 4x.
When I stick to these speed limits my failure rate drops from 25% (Burning at the fastest speed) to 1%.
Plus if I burn at a faster speed, even if Nero verifies it as fine, it is often not readable by other drives/devices.

Re:Were those disks verified? (1)

Pentium100 (1240090) | about 5 years ago | (#28751851)

4-16x for CDs (would like a lower speed, but the drive does not support it) and 2-4x for DVDs depending on how many DVDs I am recording at once. If I need to record just one CD/DVD, I will record it at the lower speed, if my friend asked me to record a lot of DVD, I will use the faster speed.

I think I should buy an old CDRW drive that can record CDs at 1-2x, they would probably last longer. Or I can record that music to a cassette.

Re:Were those disks verified? (1)

TavisJohn (961472) | about 5 years ago | (#28752135)

CD-RW are less compatible for reading than CD-R is.
I also am unsure how well CD-RW is for long term storage. RW's are short term, re-usable storage.

Not sure that hard drives are any better... (4, Insightful)

damn_registrars (1103043) | about 5 years ago | (#28751537)

The summary seems to want to lead us to backing up on hard drives:

In the past, hard disk drives were small (in capacity) and costly. To make up for the lack of affordable storage, many turned to CD-Rs.

Though I'm not convinced many consumer hard drives have shelf lives on the same order as the optical media that some of us are backing up to. Add to that the fact that hard drive interfaces do change fairly often (some of us still have systems in the transitional period between IDE and SATA), and you could have potentially more irritating problems if you were to back up to hard drives instead.

I suspect for paranoid user it may be more cost effective to backup multiple times to CD-R rather than to a hard drive. And on top of that, if one CD of your backup set goes, you are only out 700 MB or so. If you have a series of backups on a single 100+ GB hard drive, and it fails, you may be out everything that was on that drive.

Re:Not sure that hard drives are any better... (2, Interesting)

drinkypoo (153816) | about 5 years ago | (#28751559)

Though I'm not convinced many consumer hard drives have shelf lives on the same order as the optical media that some of us are backing up to.

Actually, kept in a cool dry place most hard drives will last pretty well. They only have durable SMT components on them these days. The only thing you've really got to worry too much about (Assuming you keep them away from moisture) is the bearing lube*. I suggest buying drives from different manufacturers if you're worried about that.

* I don't know if this has ever actually happened to a hard disk, but the lubricant used on the headlight switch of my 300ZX was corrosive after the passage of years, leading to a short and the failure of my battery.

Re:Not sure that hard drives are any better... (2, Informative)

adolf (21054) | about 5 years ago | (#28751803)

Fortunately, Nissan doesn't make hard drives(*).

Of course, the grease in the bearings can dry out, but that really doesn't seem to be much of a problem: It's a silicone-based substance, and it's wrapped up pretty tightly away from the ambient environment. There just isn't much for it to do except sit around and be stable... Old drives used oilite (sintered bronze) ball bearings almost as a rule, while newer ones often use fluid dynamic bearings -- and in either case, that aspect is fairly stable.

I've recovered data from hard drives that have been submerged in flood water for four days. They're durable little creatures, for sure, but even then at least half of the drives I touched after that flood were impossible to recover with my (primitive) methods.

That said, the biggest problem seems to be stiction. The heads of a hard drive normally fly slightly above the surface of the disk in operation (courtesy of the Bernoulli effect), but typically rest on the platter itself when the drive is not spinning. If left there long enough, the (very flat) surface of the head sometimes sticks to the (very flat) surface of the disk.

Sometimes, a disk can be spun up normally after a few years; other times, the spindle motor will stall trying to unstick the heads. There's various methods to relieve this striction, such as freezing, baking, or spinning the drive by hand on a tabletop and letting momentum free the heads, but they're all ugly.

So: For long-term, offline storage, I stick to offline-oriented media. Tapes might be good, DVD/CD-R might be good (and the admonished DVD-RAM is almost certainly better). Hard drives? It almost sounds like a bad joke.

(*: Not to pick on Nissan, by any means -- it seems that automotive chemistry isn't always just straightforward. I just replaced the radiator expansion tank on my BMW, after it exploded with a shotgun-like blast of steamy coolant. BMW used bad plastics in the cooling systems of on all of their early E36 3-series cars, including the water pump, the radiator, the expansion tank, the cap, and the thermostat housing. The radiator was new in 2003, the water pump was also recent, and I assumed that the expansion tank was also new with the radiator. I assumed wrong. A couple of days later, the fill cap fell apart, and failed to contain pressure. Live and learn.

Re:Not sure that hard drives are any better... (3, Informative)

adolf (21054) | about 5 years ago | (#28751577)

"Fairly often"? On what timescale?

In the consumer market: We had ATA for something like twenty years. And now we have SATA, with no replacement in sight.

Before that, we (consumers) had MFM and RLL.

And that, sir, is the complete history of PC hard drive interfaces.

So, again: "Fairly often"?

Re:Not sure that hard drives are any better... (1)

damn_registrars (1103043) | about 5 years ago | (#28751909)

In the consumer market: We had ATA for something like twenty years. And now we have SATA, with no replacement in sight.
Before that, we (consumers) had MFM and RLL.

Unless, of course, you were a Mac user. In which case you used SCSI for some time, before switching to IDE.

And now most people are using SATA.

Assuming, of course, that they are using a system that is only a few years old (or less). There are still plenty of systems in operation using IDE, as much as the drive manufacturers might not want to believe it.

And of course, if you are backing up your files, then the duration for which you want to keep those files may vary. If someone wants to keep those old pictures for 10 years or more, going to a hard drive might not be the wisest choice.

Re:Not sure that hard drives are any better... (4, Insightful)

Darkness404 (1287218) | about 5 years ago | (#28751581)

It depends though, you can get SATA to USB docks for next to nothing and I don't see USB going out anytime soon, if anything the external HD will crash (or end up being terribly obsolete) before USB gets replaced with anything more than the next version of USB. I mean, with USB appearing on -everything- from cell phones, to game consoles, to cigarette port chargers and more, I just can't see it being replaced especially when some legacy ports are still on many computers (does anyone really connect their printer via parallel port anymore? and aside from legacy systems and embedded systems does anyone still use the serial port?)

Re:Not sure that hard drives are any better... (1)

damn_registrars (1103043) | about 5 years ago | (#28751963)

I don't see USB going out anytime soon

It wasn't that long ago we thought the same about the parallel port. I suspect I'm not the only person here who used a Zip drive through a parallel port interface "back in the day".

does anyone really connect their printer via parallel port anymore?

Well, junior, we used to connect more than just that through parallel. And not everyone likes to replace printers that still work; I have a parallel port laserjet that I still use from time to time because it is the cheapest way to print available to me at home.

"Archiving" a single medium isn't necessary (3, Interesting)

Weedhopper (168515) | about 5 years ago | (#28751919)

HD storage is incredibly cheap and like others have pointed out, we've only had 3 major interface changes in the past 20 years.

I can't read anything from my first personal 10 MB HD, either, but that never mattered. Each upgrade, transferring that to a new set of drives was trivial. I still have emails I wrote 10 years ago, not because I can read the drives. Those drives have little to no utility to me as a storage medium. I have that data because it was a 250MB HD and that takes up less space on my NAS than a single 1080p movie trailer.

In five year's time, I'm not going to be interested in reading the HDs I have now because they'll have long been transferred to the 50TB NAS type solution I'll have then.

Re:"Archiving" a single medium isn't necessary (1)

damn_registrars (1103043) | about 5 years ago | (#28752013)

In five year's time, I'm not going to be interested in reading the HDs I have now because they'll have long been transferred to the 50TB NAS type solution I'll have then.

And what if your NAS fails? Or is it fully redundant RAID-1? Or are you backing up to something else?

Old news (3, Informative)

Drinking Bleach (975757) | about 5 years ago | (#28751543)

CD-Rs, DVD-Rs, whatever, the burning process might have some anomalies not picked up immediate, the media is low quality, or (more likely) the laws of physics erode away at the data. This is not secret or new information, it's been known for a long time. Granted that most of my collection now has a high amount of data loss (and I've encountered several instances with corrupt data... not all that I really care about, although sometimes I do work at recovering any damage I might find, especially if it's possible to verify "corrected" files with known good checksums, or infer the original contents (with, for example, text files)), since about 2005 or 2006, I've always made recovery (http://parchive.sf.net/) discs to maintain the maximal possibility of recovering data in the future. It effectively halves the capacity of my spindles (eg, in a 100 stack, I might use 50~60 for actual files and the rest for recovery files), but it's worth it; I've already encountered quite a few cases of bad media from after the time I started making parity files, and boy am I glad for it!

Re:Old news (1)

fatp (1171151) | about 5 years ago | (#28751835)

<quote>... It effectively halves the capacity of my spindles...</quote>

Then why not simply burn two copies with no recovery data?

And water is wet (2, Interesting)

EsJay (879629) | about 5 years ago | (#28751549)

Digital media are not permanent and who cares. Make more digital copies. Repeat.

Re:And water is wet (2, Interesting)

ickleberry (864871) | about 5 years ago | (#28751595)

Make more copies onto something more reliable or else you'll never get around to doing anything other than making copies

Re:And water is wet (1)

Darkness404 (1287218) | about 5 years ago | (#28751645)

I buy a new "main" computer about once every 5 years, and replace a HD about once every 8 years (stick the old HD in the new computer and copy data over, repeat) unless both HDs fail really quickly, I only would need to resort to optical backups for any newer data which is a lot smaller than all my archived files. Plus, none of it is really -that- important (or isn't redundantly backed up on some old laptop/netbook/flash drive/e-mail accounts) that if all the newer stuff failed I wouldn't be losing all that much.

dvdisaster anyone? (4, Informative)

MoFoQ (584566) | about 5 years ago | (#28751555)

dvdisaster [dvdisaster.net] is what I use now...both on CDs and DVDs (it also supports dual-layer)

think of it as a way to embed par2 (parity) onto a disc (it requires an ISO image that you create in your favorite authoring software, then after it's done embedding the parity in it, you can burn it)

alternately, you can create a separate recovery data which you can store on backup tapes or hard drives or on another disc, etc.

Re:dvdisaster anyone? (1)

Tontoman (737489) | about 5 years ago | (#28751625)

Here are suggestions I follow. I heard this from a professional archivist who works for Federal courts.
  1. Always burn at slower speeds than maximum speed of the burner
  2. Don't fill completely to capacity. The media burns from the inside-out. Because it turns at constant rate, the data on the outside tracks may be more affected by small degradation of the encoded pits

Another suggestion: burn 2 copies & refresh th (1)

davidwr (791652) | about 5 years ago | (#28751771)

In addition to everything else, consider burning two copies. If you aren't using archival-quality media, use two different types* of CD or DVD on two different drives.

Even better, go for 3 and copy your disks every 5-10 years. As a bonus, when you re-copy you can stop to think "do I need to update the file formats of any files on this disk."

*Be careful, do different brands doesn't mean two different manufacturers or even two different dye-technologies.

Re:dvdisaster anyone? (1)

MightyYar (622222) | about 5 years ago | (#28751969)

think of it as a way to embed par2 (parity) onto a disc

I'm not trying to be smart, but why not just burn disks full of par2 files? I'm asking because that is exactly what I currently do. It has the added advantage of letting you span disks with data that is larger than the size of one disk. Just make a disk image of whatever size, and then act like you're going to post it on usenet except burn to disk instead.

Not surprising (1)

ickleberry (864871) | about 5 years ago | (#28751587)

Ever since the good ole days of CD-R I used to burn them to find they didn't really work after a couple of months. I actually think all optical media is like that - you burn it, should last for a few weeks after that it's hit or miss. Pressed CD's seem to last forever but not anything you burn yourself

After all it seems the only reliable storage is flash memory, preferably SLC

Buy Quality Blanks!!! (4, Insightful)

the eric conspiracy (20178) | about 5 years ago | (#28751593)

"Studies" like this are useless if they don't include information from the codes off the CD's (not the label on the box!) as to who the manufacturer is.

Get the Taiyo Yuden and MAM-A Gold blanks and you won't have issues like this.

Also please read the Wikipedia article on CD-ROMs, and expecially the references. You WILL end up with better burns if you do.

Re:Buy Quality Blanks!!! (4, Informative)

analogue_guy (892989) | about 5 years ago | (#28751655)

Mam-a is not what it used to be.

Buy Taiyo Yuden or Falcon.

Re:Buy Quality Blanks!!! (1)

niktemadur (793971) | about 5 years ago | (#28752023)

Get the Taiyo Yuden and MAM-A Gold blanks and you won't have issues like this.

Amen to that. The day I bought my first spindle of Taiyo Yudens was the day I stopped burning coasters, and I've gone through about 200 of them.
Too bad TY has not made DVD-R DL or DVD+R DL discs, I've had to use Verbatim for those, and considering they're quite a bit more expensive than regular DVDs, the failure rate is too high; even while burning at 2x, I often get the error message "Verification failed, bad sector something something", using Toast Titanium on an iMac and an external Sony disc burner hooked up via Firewire, as the internal Pioneer burner was an absolute piece of crap.

Re:Buy Quality Blanks!!! (4, Interesting)

cdrguru (88047) | about 5 years ago | (#28752069)

The "codes" on a CD-R that indicate the manufactuer are pretty much meaningless. Why? Because they are often the code assigned to the manufacturer of the stamper.

Stampers are hard to make and require a cleanroom, lots of chemicals and skilled people. After you have a stamper, you put it into a machine and any idiot can turn out CD-Rs. So plenty of manufacturers with the cleanroom facilities and the knowledgeable staff sell stampers. So you have some place like Ritek that will sell anyone stampers. Now Wong's Cheaper Discs buys up some stampers from Ritek and starts turning out discs.

Since Wong's Cheaper Discs are a few cents less than anyone else's that week, Memorex and lots of other folks buy up discs from Wong's. Sadly for Ritek, all the discs from Wong's have the manufacturer code from Ritek. Now someone from Ritek might be able to tell you that these discs were not actually made by Ritek, but it is going to take someone familiar with their processes to tell you that. It is not obvious.

So the manufacturer codes on discs are pretty useless. About the only thing you can do is buy discs from reputable manufacturers where you actually know who the manufacturer is.

10% Fail within a few years (1)

dasmoo (1052358) | about 5 years ago | (#28751639)

The rest are lost, or borrowed and not returned. I wouldn't trust CDs or DVDs for backups. They're not big enough now anyway.

Re:10% Fail within a few years (2, Insightful)

Darkness404 (1287218) | about 5 years ago | (#28751695)

Depends what you mean by "big enough", other than things that are redundantly backed up (my music and photos are on several MP3 players/iPods along with various flash drives, SD and other memory cards while other files are on one of my e-mail accounts) anything that really -has- to be backed up can fit easily in a CD-R. Sure, that won't get me every single movie I've ripped from DVD into a different format, sure its not going to get me all my applications settings, sure it probably wouldn't hold the 20 or so half-coded projects I've started but never finished. But all those are really pointless. I mean, sure, it would be a pain to re-rip all those DVDs, but over half of them I don't think I've ever really watched on my computer save for making sure the rip was done correctly, despite how I would like to finish my half-coded FPS written in python, I doubt I ever would. Other than a few financial documents, everything else is simply trivial.

Re:10% Fail within a few years (1)

Martin Blank (154261) | about 5 years ago | (#28751821)

I used to think the same thing. Then I started doing an inventory of my data. Scrapping the ISOs, movies, music (which for me actually will fit on one DVD), games, and all the rest, I need two DVDs to do a backup of the data that I have a real need to keep: e-mail, personal documents, and photos that I've taken, plus a few extra files like encryption keys. It totals up to about 7GB -- easily backed up on a regular basis. Once Windows 7 hits RTM and I can get a final installation of it in place off of Technet, then my backup mechanisms will be further streamlined to include regular backups not only to a local drive, but also to a NAS as well as regular backup to DVD. I'm also considering getting another 1TB drive for the NAS, and periodically powering down the unit, removing a drive to store it off-site, and then rebuilding the array with that drive, cycling them around to minimize the chance of catastrophic damage to the home causing loss of data. I'm also working with a friend, so that we can backup the connections to each other over the Internet via IPSec VPN across the country in case a large-scale disaster causes sufficient destruction that both my home and the storage site for the backup drive are lost.

Paranoid? Yep. But then, the possessions that matter most to me are the memories stored on these drives, and aside from an hour or two of initial setup (plus whatever time it takes to replicate the drive, should I go that route), there's not really much to it on a running basis.

CDs do seem flaky (1)

junglebeast (1497399) | about 5 years ago | (#28751649)

I went through a period of backing up things on CD's, I liked the tangible backup...I stored them in those CD booklets that hold several on a page, zipped them up and put into storage. Now when I take them out, frequently they are unreadable. No physical damage, scratching, or even light exposure. Weird huh

Ritek - I hate you. (1)

Falcon4 (946292) | about 5 years ago | (#28751673)

Well, when all people buy are the cheapest brand of CD-Rs (or, in my case, the cheapest being the only thing available), and they're all manufactured by one company crapping out shoddy products (Ritek)... what do you expect? If 90% of CD-Rs adhere to substandard manufacturing techniques, I'm surprised only 10% have failed prematurely.

Magnetic storage is still best. Unlike optical media, magnetic material can be digitally refreshed without consuming additional resources (burning a new CD-R). Sigh.

Re:Ritek - I hate you. (1)

MightyYar (622222) | about 5 years ago | (#28752001)

magnetic material can be digitally refreshed without consuming additional resources

CD/DVD-RW? I have used both. DVD-RAM isn't as popular, but is used essentially exactly like magnetic media.

My experiences with CD-Rs - some good, some not (5, Interesting)

PatMcGee (710105) | about 5 years ago | (#28751733)

I recently tried reading a bunch of audio CD-Rs burned between 2003 to 2007. I used Exact Audio Copy on a Toshiba drive. I was able to get error-free reads from about half the disks recorded in 2003; about 3/4 of the ones from 2004, and from all the ones recorded after that. On the early ones that worked, sometimes EAC took a couple of hours to do the reads, which means it was doing a lot of retries. On the later ones, the transfers were mostly just a few minutes. On the ones that reported less than 100%, sometimes EAC spent 50-60 hours trying.

For the disks that I could not get 100% reads on from the Toshiba drive, I tried them in several other computers using a variety of programs. Mostly I was not able to get results as good as EAC on the Toshiba drive. I tried two Mac Mini's using Max and an old Mac G3 using cdparanoia from the command line, and got lots of failures. Then I tried Max on my MacBook and they all read perfectly. Go figure.

I theorize that one reason the disks had errors was that they were labeled using a Sharpie. According to the NIST report on CD-R failures (nvl.nist.gov/pub/nistpubs/jres/109/5/j95sla.pdf), this is a really, really bad idea. Since I read that report, I've been adamant about using only water-based markers on CDs and DVDs.

Re:My experiences with CD-Rs - some good, some not (0)

Anonymous Coward | about 5 years ago | (#28751907)

Your comment is mostly good. Your data is interesting, and I think I have heard elsewhere about Sharpies and such causing the disks to degrade. However, you seem to have linked to the wrong thing, as the report has nothing to say about markers being used to label disks at all.

Storage under "ideal conditions"... (1)

willoughby (1367773) | about 5 years ago | (#28751739)

So just what are the "ideal conditions" for storage of optical disks?

And, while I'm asking questions, has anyone ever experimented with submerging disks in (water | mineral oil | etc) to see if that would reduce long-term degradation? If we're talking 5 years or more I wouldn't mind drying/cleaning them to get my data.

Re:Storage under "ideal conditions"... (2, Informative)

Anonymous Coward | about 5 years ago | (#28751921)

cool dry place w/ no sunlight / UV. get a large CD storage folder (they usually have em for holding 500 or so disks and leave it in a drawer.

see here : http://www.supermediastore.com/cd-dvd-wallet-wallets-cd-holders-cd-storages-organizer-epv-520.html

520 Disc Capacity CD DVD Wallet Case offers Koskin/Black Leather-Like Quality CD/DVD Portfolio, Organizer, Case, Wallet, Holder with Sturdy Handle, Comfort Shoulder Strap, Removable/Refillable Binder Style Inserts with Easy On/Off Switch. Perfect for professionals looking for a sturdy, heavy duty DVD CD wallet. $18.99 for 2+.

CD-Rs Design is Flawed. DVD-R More Reliable. (4, Interesting)

Ron Bennett (14590) | about 5 years ago | (#28751745)

CD-Rs design is very flawed in that the recording layer is near the surface as opposed to being well protected in the middle, as it is in DVD-Rs.

I've had numerous CD-Rs that were well cared for get flaky after a year or so; data is usually still there, but requires use of various recovery tools.

DVD-Rs have been very reliable in comparison - never had a problem.

With that said, what I do for archival data is use two different brands of DVD-R *plus*, when possible, save two, sometimes even three, duplicate copies of the data on the same DVD-R. That way I have two to as many as six copies of the data, often including dups on the same DVD-R allowing for faster, more convenient recovery.

Ron

the best archival medium I've used thus far (2, Funny)

Tumbleweed (3706) | about 5 years ago | (#28751747)

...is the venerable 5.25" floppy disk, circa pre-1985. My Apple // disks from that time are still readable. It takes rather a long time to back up my 1TB WD "Green" HD onto the Apple //GS I have networked to my main machine, but hey, backups are important! :)

Punched cards or punched tape (3, Funny)

davidwr (791652) | about 5 years ago | (#28751805)

Punched cards or punched tape using something stronger than ordinary paper is very good for long-term storage. In ideal conditions it can last millennia.

If that's not good enough, non-organic inks on cave walls and cut indentations in stone can last even longer if protected.

OT: "It's been 4 minutes since you last successfully posted a comment" WTF? When did /. start limiting you to 1 comment every 4 minutes?

how to get good burn quality (5, Informative)

analogue_guy (892989) | about 5 years ago | (#28751763)

I burn thousands of CDs and DVDs per week and here are some tips

  - use pro grade media from Taiyo Yuden (Made in Japan) or Falcon (Made in UAE). Verbatim still makes some good media but you have to know what to look for (Datalife Plus) because they also buy cheap media and rebrand it.
  - burn cd-r at 16 or 24x. 32x is ok for short-term use. Even the best discs will fail if you burn at maximum speed.
  - burn dvd-r at 8x
  - if you must burn dvd-r at 16x, test your quality regularly for signs of failure.

how to test the quality:

  - Plextor made good drives bundled with Plextools testing software but they are no longer making their own drives. For a replacement to Plextools, see Opti Drive Control at cdspeed2000.com

Re:how to get good burn quality (1)

Ron Bennett (14590) | about 5 years ago | (#28751883)

Yep, slower burn speed can make a difference. One of those details few people are aware of.

For DVD-Rs, I limit burning to 4X. Probably overly conservative; 8X, as you suggest, is likely fine too.

Ron

Note the "idal conditions"... (1)

gweihir (88907) | about 5 years ago | (#28751769)

I have had CD-Rs fail within weeks after perfect verifies. You should expect a lot less than the given times in "normal conditions".

Why would you believe? (1)

Dupple (1016592) | about 5 years ago | (#28751829)

How on earth can something be prooven to last a thousand years if it hasn't been around that long? Only the gullible or stupid would believe such a claim. Reburnning often is the only way to be sure

(Except if you're dealing with Aliens in which case just nuke 'em from space - that's the other way to be sure)

And up to 100% of TFA is anecdotal (1, Insightful)

Anonymous Coward | about 5 years ago | (#28751853)

TFA mentions that there were various brands that exhibited failures, but this ultimately tells us nothing. CD-R branding is completely meaningless. What matters is the material/dye composition and the OEM, and the author did not control for this criteria.

What you are most likely to find is that discs made from early materials are more prone to failure, as are discs from disreputable OEMs. These are the relevant facts for quality, and the lack of understanding about what determines the quality of a CD-R is what leads to popular myths, my favorite being the one about writing slowly to have a better or longer-lasting copy. If you have to do that, it means your burner and/or media is junk, and you are merely performing the voodoo that is necessary to make sub-specification parts work. A quality burner and media will write at 100% speed and it will be just as good as writing it at 2X or 4X or whatever other number people care to pull out of their collective ass.

I have written hundreds of CD-Rs myself, and the only archival failures I've had have been due to cheap media -- and those tend to fail fairly quickly, it doesn't really take 9 or 10 years, and there's a pretty good chance that the bad discs in TFA died a long time ago, shortly after burn, but he's only gotten around to checking them now. Some of the cheap discs in my collection actually started turning color, as after a couple of years there was a visible gradient going from the outside towards the inside. If you can see the physical degradation of the disc then you know the data doesn't really have a chance.

As always, backing up doesn't mean making one copy and then putting it somewhere forever until it's needed. Backing up means making copies on a periodic basis. If you wait 9 or 10 years between backups, you might as well have kept your data on the hard drive the whole time.

4 CD, Raid 5. (5, Informative)

evilviper (135110) | about 5 years ago | (#28751857)

I used-to make 2 CDs of every ISO, until I figured out how best to utilize PAR2.

PAR2 calculates parity information on a set of files, and writes out a file which can be used in the event that any of the files is damaged. This is quite similar to RAID-5, but PAR2 is more robust, and works on any files, not just equally sized hard drives.

Though it's no help on DVDs, CDs work GREAT with PAR2, because of their two different methods of recording. Mode 1, as all regular files are stored, reduces the amount of space available by about 12.5%, using that space for additional error correction data. Audio CDs, and Video CDs, where a single bit error isn't nearly as critical, are recorded in Mode 2, with substantially reduced error correction, but about 100MBs more usable space available.

PAR2 is similarly resilient to errors, so it can safely be used with Mode 2. This allows much more space for the parity information, and the opportunity to be safe against, and correct, respectively more damage to a disk.

Specifically, I recomend a 4-disk parity set. You fill 3 CDs full of data, and tell PAR2 to calculate 37% recovery data on those files. The first 33.334% allows you to RECOVER THE DATA FROM ONE COMPLETELY LOST CD, no matter which of the 3 it is. That still leaves you with a margin of 3.667%, so those two CDs you DO have, can have a few bad sectors as well, and all the data from the lost CD, as well as undamaged versions of the files on the two lightly damaged CDs can be recovered. Alternatively, if you DON'T lose an entire CD, all three (4 actually) CDs can have numerous bad sectors, in any distribution, up to a total of 37% of all the discs, and pristine data can still be recovered.

The method to do all this is quite simple. Just run the par2create command, telling it to create 37% recovery information. Then take the resulting BASENAME.Par2+??????? file, and create a CUE file, describing a CD with a single track across the whole CD, with the PAR2 file as the supposed audio data. eg.:

FILE "par2.bin" BINARY
    TRACK 01 MODE2/2352
        FLAGS DCP
        INDEX 01 00:00:00
    TRACK 02 MODE2/2352
        FLAGS DCP
        INDEX 00 00:04:00
        INDEX 01 00:06:00

Now, any CD recording software that understands CUE files will happily record this to disc. On Unix systems, you can choose cdrecord, or cdrdao.

Now, like regular audio CDs and Video CDs, you can't just use or copy this data off the disc like a normal file on a CD. There are programs for converting VCDs into regular files, something like dat2mpeg, but I prefer a more generalized tool that can do the job:

    mplayer vcd://2 -dumpstream -dumpfile par2.bin

You'll note that checksums of the file and the data on disk don't quite match... This is because, in mode2, data MUST be padded to the block size. PAR2 files are fine with it, and the padding is silently discarded.

Something like DD_RESCUE to copy the (normal) files off the other CDs, in the event of damage, is probably necessary as well. Then, once you've got 3CDs worth of data (eg. 700MB CDs x 3 = 2100MBytes) you can run par2recover and all with be repaired, like magic.

The only footnote being that calculating the parity information isn't fast, so this method is probably slower than just recording 2 copies of every CD. Also, if you lose more than 37% of the data across all the discs, the error-free originals can't be recovered. However, I consider it more reliable than duplicate discs, if only because the odds of an error on the same sector of two discs (or one disc lost, and the backup with a few errors), seems more likely than 37% of the discs being damaged beyond hope. And as an added bonus, you save 1/3rd on your CD-R purchases.

A good plan but ..... (0)

Anonymous Coward | about 5 years ago | (#28751989)

I only record the first 1K of the disk - if I ever need the back-up, I make the 1K file available on a torrent. The *IAA then takes me to court, where they present me, with what they assure me is a completely accurate copy of the file - This allows an entire collection to be stored on a single DVD. It also provides for off-site storage. Retrieval time can be a bit lengthy however, and costs involved can seem excessive. Sometimes only the file name is required for the *IAA to present we with a complete copy. So I must give them credit for being able to extract the entire contents of a file, from nothing more than a filename. Must be that DMA they speak of so often.

I had a different problem (2, Interesting)

British (51765) | about 5 years ago | (#28751871)

I go and reinstall windows on my dad's machine. I use an nLited burnt CD I made(HP made CD) and it won't even boot. Tried a linux recovery CD(same maker of CD), would not boot. Somehow, out of the 6 tries I was able to get the XP install CD to boot. It did. Failed about halfway, asking for the file "ASMS", which didn't exist(but a folder did).

So, bad Cd? I fire up a virtual machine, and install XP in the machine and it works flawlessly.

I go back to my dad's machine & eventually try my legit store-bought XP install CD, and it continued to install. I burn a CD of my dad's backed up data(again, an HP cd), and it reads just fine on my machine I burned it from, won't read at all on my dad's system.

Wow, I'm lucky.

Possible explanation: Conditoiin of the CD (0)

Dullstar (1581331) | about 5 years ago | (#28751899)

They could be stored in perfect places as far as the atmosphere conditions go, but the CD itself may be in horrible condition. If the condition is too bad, how's it supposed to function?

Physical damage trumps all other considerations (3, Interesting)

silverspell (1556765) | about 5 years ago | (#28752035)

I'm the kind of person who usually does a fair amount of research before he leaps, and so when I first started burning CD-Rs, I did everything more or less by the book. I used quality media (Mitsui and Taiyo Yuden), quality burners (Plextor), always verified my burns, and never used any crazy high speeds. My CD-Rs have held up well in many aspects, and I've only had a few physically intact discs that went bad for no apparent reason (most of which are from what may have been a problem batch of Mitsui Silvers, burned around 2000/2001).

But no one really made it clear how physically fragile the damn things were, especially in comparison to pressed silver CDs. I kept my backups in a booklet-style binder. Yes, I know that's considered less than ideal, but these discs weren't burned solely for archival purposes -- I needed to be able to page through them efficiently. Most of them were taken out and used every so often -- say, four times a year on average, sometimes more -- and never knowingly abused.

Over time, the foil on quite a few of them started to flake off. Unbranded Taiyo Yudens, which are so often acclaimed, seem to be the most vulnerable -- I've had quite a few that developed holes in the foil, especially near the edge. It's a shame, because the discs read beautifully otherwise, and seem to ace most media tests. But the foil seems all too easy to damage.

(I've also lost a handful of Mitsui Silvers that way, whereas Mitsui Golds seem to have a more robust armoring on top, as do some of the 2nd tier discs I've tried -- Sony, Maxell, TDK, Memorex. Meanwhile, I've seen no evident physical damage to my DVD-Rs so far; fingers crossed.)

Marketing 101 - spin paranoia (0)

purpleraison (1042004) | about 5 years ago | (#28752067)

This is crap. Seriously, has anyone here ACTUALLY had a CDR not work unless it was scratched to hell and back?

Seriously....

what's a CD-R? (1)

AnAdventurer (1548515) | about 5 years ago | (#28752075)

No really, do people depend on these? (funny story, I went to the printing department at the local Officemax to print post cards for my business with a DVD-R and they said the computer they had did not read DVD-R's)

Every time I have used a CD-R it was only as a temporary storage option (as in to take big photo files to Costco or aforementioned Officemax) until DVD-R prices came to be pretty much equal or lesser. We have all know CD-R's have high fail rates, freaking ZIP dives have better life spans (I think, I have nothing to back that up with - just fuzzy memory from back in the "old days").

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