[Pio2001]

Pressed CDs and burned CDRs are completely different.
The lifespan of pressed CD is unknown, but superior to 20 years (except for rare cases of bronzing or mold).
The lifespan of CDRs is very variable. Often around 2 to 5 years, it can be as short as several monthes, or as long as 10 years and more.

In Hydrogenaudio.org, a survey was once made about the brand and longevity of CDRs. The two remarkable brands were Verbatim Datalife Plus (made of Metal Azo), and Tayo Yuden, both of which it was nearly impossible to find a case of dead CDR.

I am also curious about the longevity of memories. Video games of old were sometimes sold as cartridges with some kind of electronic memory inside. I wonder if they still work.

The engine of hard drives sometimes fail, which turns the whole data unreadable at once.

I store my music in the main computer, with an external backup on hard drive. I make backups once a month, with different external drives (so as not to erase the backup before making a new one), and I always let the software check the copy after the operation, which means that all written sectors are readable and identical to the original.

Having the backups all connected at once is a bad idea, I think. A virus may erase all accessible data as soon as it sees a backup software running (that would be very nasty from the hacker, but hey, some hackers are).

 

[JadeEast]

One of the issues of backing up is the computer system has to be backwards compatible along with the software used to archive. I've have to keep a older mac os9 available to restore archives from a SCSI tape drive. In the analog realm the machines for playback have to be sound, how many VHS machines are there going to be in 20 years time or what would you do with a floppy disk today? I'm not saying these are good formats to back up on just the physical mediums for storage change.

 

[cerbie]

Quote:

Originally Posted by Pio2001 /img/forum/go_quote.gif In Hydrogenaudio.org, a survey was once made about the brand and longevity of CDRs. The two remarkable brands were Verbatim Datalife Plus (made of Metal Azo), and Tayo Yuden, both of which it was nearly impossible to find a case of dead CDR.

To elaborate for new guys, I recently used up my last proper MCC Verbatim Datalife Plus, and they have not been produced in years, in any identifiable fashion! What used to be top-notch media on U.S. shelves is now a throw of dice.

TYs are currently the only choice for great quality CDRs, to my knowledge.

Having not gone and ordered new TYs quite yet, and using most CDRs in my car and at work (music), the difference in quality is astounding. I still listen to TY and MCC discs covered in scratches, warped and yellowed from the sun, some a couple years old...I'm lucky if anything I pick off the shelves lasts two months. I've got some ancient good MCC discs going on ten years old, now, properly stored, that still work great, on the occasion I dig them out. I'm talking burned on SCSI burners, because the IDE burners were just announced, kind of old

(some might really be 10, now, come to think of it!). No TYs that old, but no failures of them, yet, either.

Quote:

I am also curious about the longevity of memories. Video games of old were sometimes sold as cartridges with some kind of electronic memory inside. I wonder if they still work.

Usually, yes. Most were made as ROMs, with a battery for other stuff, and replacing the battery can bring new life. I think it's too much work, myself, but I'm into the game itself, not the nostalgic aspect.

Quote:

Originally Posted by JadeEast /img/forum/go_quote.gif One of the issues of backing up is the computer system has to be backwards compatible along with the software used to archive. I've have to keep a older mac os9 available to restore archives from a SCSI tape drive. In the analog realm the machines for playback have to be sound, how many VHS machines are there going to be in 20 years time

Dunno, but apparently beta will be around in several decades, and some guy named Spike will give a retro electronics nerd a heart attack over one.

Quote:

or what would you do with a floppy disk today?

Hope it works, and move it to CD. Quote:

I'm not saying these are good formats to back up on just the physical mediums for storage change.

Use an older computer with a compatible controller, move to an exchange medium (PCI or ISA old SCSI->PCI SATA->HDD->integrated SATA->whatever the new backup medium is). While sometimes it may not be quite so easy, as long as one is on top of things, it usually will be. You would also be surprised what you can get, if you look hard enough; like modern mobos with ISA slots, hard drives able to go down to the 8GB limit, etc., letting you often use old OSes, even, as you move your data.

For us normal folk, who might wear tennis shoes, or the occasional python boot, checking your bacups every now and then for high error rates, in the case of optical media, and simply transferring around, in the case of tape or HDD, will likely be enough. The key is to make sure your data isn't gone before you move to another medium, and don't discard the old medium once done. Keep on top of it, it may topple on you.

I'd probably dig a Uni level course or two on data preservation

. Most of my knowledge comes form data loss happening to myself or my father, in stressful and pragmatic ways, rather than solidly backed theory or history on any good scale.

 

[bigshot]

I'm the director of a digital archive, and our strategy is based on redundant backups on hard drives, and transferring information to new drives and converting file types to current standards every five years or so. No medium is eternal. Digital has to keep moving to keep alive.

See ya
Steve

 

[montell]

I'm going to drop another one in here. Magneto-optical drive (MO-discs) are ultra reliable for long-term storage. Goverments uses them alot for legal document storage. Hospitals to store medical imaging and other sensitive materials. They are noted for their high reliability, long life, and (for that time) high storage capacity. The minidisc is an example of a MO-disc.

I dont know if flash is more reliable though.

 

[SenjStevo]

Whats the best file format to store music? FLAC or WAV or other?

 

[fjf]

1-Lossless-compressed Wav. Then you can convert it to lossy (mp3, etc) if you want to shrink it.
2-Flac is the best because it is open source and you dont rely on some company's proprietary system that can disappear some day.

 

[SenjStevo]

Quote:

Originally Posted by BradJudy /img/forum/go_quote.gif NIST (US government research group) did a couple of studies on the longevity of CD-R and DVD-R media. Here's the first one - http://www.itl.nist.gov/iad/894.05/d...ilityStudy.pdf

According to this study Gold+Silver, Phthalocynanine CD-Rs are the most stable. The study doesn't appear to test Gold, Phthalocynanine CD-Rs however.

Theres another paper i've not got to hand which goes into handling and enviromental conditions. Stuff like humidity, temperature and light exposure. It's interesting, i'll try and post it later.

Apparently there is a program called CDR Identifier which can tell you the specifications of CD-Rs such as Dye type.

 

[japc]

Quote:

Originally Posted by SenjStevo /img/forum/go_quote.gif According to this study Gold+Silver, Phthalocynanine CD-Rs are the most stable. The study doesn't appear to test Gold, Phthalocynanine CD-Rs however. Theres another paper i've not got to hand which goes into handling and enviromental conditions. Stuff like humidity, temperature and light exposure. It's interesting, i'll try and post it later. Apparently there is a program called CDR Identifier which can tell you the specifications of CD-Rs such as Dye type.

Interesting, please post the paper.

On linux you can use dvd+rw-mediainfo or wodim -atip to identify the CD/DVD. For instance (grabing one random "imation" cd with debian I had here on the table):

Disk sub type: Medium Type B, low Beta category (B-) (4)
Disk type: Short strategy type (Phthalocyanine or similar)
Manuf. index: 69
Manufacturer: Moser Baer India Limited

Interesting site to check IDs and quality: digitalFAQ.com | Blank DVD Media Quality Guide

 

[SenjStevo]

It's been a while, but i think this was the paper i was talking about. It's a quick reference guide for storing media.

I've posted a website i've created for anyone who is interested with a feedback survey.(See first post)

 

[gadgetman]

I keep my medias on an Unraid server with a proper spare drive on standby in case any of the drives die.

 

[iriverdude]

Multiple mirrored RAID-5 servers in different locations is probably as good as you're going to get. With couple of servers with previous backups, for example you don't want to backup your data if it's all been corrupted before you realise it's corrupted. For example server 1, 2 and 3. 1 is backed up onto 2, 2 onto 3, etc. So if you backup onto 2 then find out data corruption (perhaps a virus has infected server 1 and damaged data, you've still got server 3 which is clean with intact data)

 

[ThePredator]

Quote:

Originally Posted by iriverdude /img/forum/go_quote.gif Multiple mirrored RAID-5 servers in different locations is probably as good as you're going to get. With couple of servers with previous backups, for example you don't want to backup your data if it's all been corrupted before you realise it's corrupted. For example server 1, 2 and 3. 1 is backed up onto 2, 2 onto 3, etc. So if you backup onto 2 then find out data corruption (perhaps a virus has infected server 1 and damaged data, you've still got server 3 which is clean with intact data)

On tape and in Iron Mountain would be better.



RAID is basically useless for long term data integrity as it was designed for online integrity. Short term incremental backups with long term full backups to offline media is the proper (easy) way to maintain data.

 

[SenjStevo]

Whats Iron Mountain? Are tapes used frequently to back up servers?

 

[ILikeMusic]

In my experience concern over CDR life seems to be greatly overstated. I can't remember finding a single CDR that I couldn't read and I've been using them back from near the beginning of consumer availability, or at least 15 years. Will they all begin to fail next year? Who knows, but remember that CD reader technology improves over time as well.

And besides, in most cases your data doesn't have to outlast the end of time... it only has to outlast you...