Disc rot

[harry]

I thought CDs etc were almost indestructible but apparently not.

[greyridersalso]

We moved home about four months back. When packing, we binned around 150 CD s and a lot of DVDs which had backed up software, pictures, docs etc, all n icely rotted and unreadable. They'd been housed out of daylight, in an even temperature and all in cases. Nothing lost as most of them were either out dated anyway or still current on hard drives, but you can forget spreading jam on them and using them for life time storage.

[mark]

If you leave them exposed to sunlight for a few weeks they yellow and eventually they start shedding a very thin film/skin.

mark

[Nightjar]

You get what you pay for and the cheapest are adequate for many purposes. If you want the data to last, buy archival quality DVD+R disks and store them in cool, dark, dry place in rigid acid-free plastic containers.

Colin Bignell

[Andrew Gabriel]

Many of the early audio CD's turned out to have rather short lives. In that case, it was the label printing ink eating the aluminium. Ironically, it was some of the more expensive labels that were most impacted by this. I had a couple of Deutsche Grammophon CDs which were impacted (they replaced them for free), but none of my cheaper label CDs were.

[Bill]

In message , Nightjar writes

Yes, my son's house came with a load of CD's tied on to canes lying all round the garden. They were better than nothing, but the crows still dug up the lawn for the chafer grubs even when he re-planted the canes everywhere.

I have had CD's develop radial cracks, DVD's that have split horizontally into two, leaving 2 plastic disks, one clear, one "silver", CD's and DVD's that have just become unreadable with pinholes and bloom and some with nothing obvious. CD-R's and DVD-R's are worse than commercially manufactured ones, but there have been failures in all types.

For the unique material that I want to keep, I'm now reduced to pulling audio and video off whatever medium it is on (tape, DAT, MD, cassette, CD, and so on), copying onto 2 HD's in my backup machine, copying onto another HD external to a separate machine, but keeping things in CD or DVD size chunks, so that they can be easily and regularly backed up to newer CD's and DVD's.

I have had failures with CD's of all ages - I started with CD-R's when HP brought out the first "affordable" CD recorder for £1000 - and both cheap and expensive ones. They have all been stored in a cool, dry place in cases and within other boxes, so in total darkness. Oh and a JVC CD-RW that I used for the first time last week seemed to have warped inside its case.

The other problem is documentation of what I have where. I've tried many, many database type programs, but all have been very inflexible. I'm now loading things into a raw MySQL database in the hope that sometime in the future it will still be readable and someone, maybe me, will be able to cobble together a more user-friendly front end.

I find the whole subject totally depressing.

[Tim Lamb]

In message , Bill writes

Sure it was Crows? Foxes do that:-(

[meow2222]

For long term info storage I think one can't beat plain text. Its the most universal of all data formats, and has been for a long time. More or less e very computer can read it, its easily searched etc, and can be expected to stay in use indefinitely - which is not the case with database or word proc essing formats.

NT

[Adam Funk]

I'd better check my digital photo archives then. I've been relying on having 3 copies of each DVD (containing 1 or 2 years of photos) stored in different places.

[Nightjar]

DVDs have better protection for the write layer than CDs. +R has better error correction and better burn control than -R. RW discs are not good for archival use. Hence DVD+R is the best choice even if you don't spend the extra on gold layer archival quality discs.

Colin Bignell

[John Williamson]

I stopped using recordable optical media for archiving stuff the first time a CD-R showed up as unreadable a few months after it had been written about 15 years ago.

I now use them only for distribution to others and as masters for the CD makers. Even then, I send the files on a USB stick as well, in the form of an .iso disc image.

[Man at B&Q]

not.http://en.wikipedia.org/wiki/Disc_rot

Have you been hiding under a bridge for the last 20 years?

MBQ

[Man at B&Q]

The medium is more important than the message.

or less every computer can read it,

Not if it's on, say, 8" floppy.

MBQ

[Andrew Gabriel]

For any types of digital archives, you need to factor in checking them periodically, and recreating them on new media as media deteriorates or becomes inaccessible due to obsolescence.

At the moment, I can keep all my data on my server, as well as having long-term backups, so I'm not entirely dependant on just the backup media, and I do recreate it from the server occasionally. There may come a point when I have to take some of the data off-line to long-term storage only.

Commercially, those who need to store large ammounts of data (e.g. for legal or business reasons) tend to use enterprise tape as it's by far the cheapest per terrabyte, but the up-front and ongoing costs are far too high for the tiny data volunmes home users have.

[RJH]

+1. Although I haven't had many 'pre-recorded' (shop bought music or software) fail. Most of the ones I recorded are now useless.

Rob

[John Williamson]

Same here. I remember one of the Philips production plants having problems with the edge seal on some early commercial CDs, letting the air in and destroying the aluminium coating, but that problem was solved long ago, and all the affected CDs were binned or replaced before 1985 or so.

[PeterC]

I was under the impression that high quality DVD-RAM disks were the best, if not universally playable.

[Eric]

If you have the money

[Richard Russell]

Archive-quality (gold or platinum) recordable DVDs are often stated as having a lifetime of more than 100 years. Of course that can only be estimated by accelerated life testing, and can't be guaranteed, but it's good enough for me.

Richard.

[Andrew Gabriel]

What would you do with your DVD in 100 years time? If I gave you a 100 year old gramophone record (12", 120RPM), can you find a record player for it?

Could you even read a 20 year old 5.25" floppy or a 25 year old

8" hard sectored floppy?