Does CD/DVD rot really exist?

[kenny1999]

Long time ago I happened to read some articles about CD/DVD rot, I don't remember the details now but the key point was - Data stored on CD/DVD would lose a little bit over time. 

Is it real? If a CD/DVD disc is kept and stored normally, will there be some data loss after 10 or 20 years?

[studiot]

4 hours ago, kenny1999 said:

Long time ago I happened to read some articles about CD/DVD rot, I don't remember the details now but the key point was - Data stored on CD/DVD would lose a little bit over time. 

Is it real? If a CD/DVD disc is kept and stored normally, will there be some data loss after 10 or 20 years?

Yes and no .

Writable / rewritable media will deteriorate with some.
Some earlier chemical formulations were more unstable than others.

More recent ones are better but do not have an indefinite life.

 

Mechanically pressed media have an expected life of hundreds of years, no one really knows how many becasue they haven't been around long enough to start failing.

 

Of course this excludes media that was defective from the beginning or physically damaged later.

Edited December 22, 2022 by studiot

[exchemist]

5 hours ago, kenny1999 said:

Long time ago I happened to read some articles about CD/DVD rot, I don't remember the details now but the key point was - Data stored on CD/DVD would lose a little bit over time. 

Is it real? If a CD/DVD disc is kept and stored normally, will there be some data loss after 10 or 20 years?

There is no reason to think this article is wrong: https://en.wikipedia.org/wiki/Disc_rot

[John Cuthber]

4 hours ago, studiot said:

no one really knows how many becasue they haven't been around long enough to start failing.

Enough have failed that we know they really won't "last forever".

 

4 hours ago, studiot said:

Of course this excludes media that was defective from the beginning

That looks a bit like a "No true Scotsman" argument.
 

[kenny1999]

13 hours ago, studiot said:

Yes and no .

Writable / rewritable media will deteriorate with some.
Some earlier chemical formulations were more unstable than others.

More recent ones are better but do not have an indefinite life.

 

Mechanically pressed media have an expected life of hundreds of years, no one really knows how many becasue they haven't been around long enough to start failing.

 

Of course this excludes media that was defective from the beginning or physically damaged later.

If a disc is just stored and kept in a box, sometimes taken out and wiped clean, no accident or damage, is there still any data rot? Is data rot caused by human damage or accident or is it a natural deterioration?

[studiot]

11 hours ago, kenny1999 said:

If a disc is just stored and kept in a box, sometimes taken out and wiped clean, no accident or damage, is there still any data rot? Is data rot caused by human damage or accident or is it a natural deterioration?

It is important to distinguish between both factors,

That give four possible situations.

1)  Two types of CD

2) Two types of degradation 

 

All types of CD are subject to scuffs and scratches and greater damage. Some of these can be polished out.
All types are also subject to the chemicals from fingers over a much longer timescale.  This trpe of degradation only affects the surface and can be cleaned / polished out.

Cds that are made by mechanical stamping of physical pits are not subject to degradation of the pits over human timescales, but these discs may suffer surface damage that makes them not properly readable.

CDs that are made by creating flat areas of chemical change with a writing laser are susceptible to both light (yes storing these in a lightproof box will extend their life) and other chemical degradation that is not light related.
The chemical used vary for patent reasons. Some brands gained a very bad reputation for loosing all the readability after a year of two.

What more is there to say?

[Moontanman]

I've had Laser Discs that deteriorated, the reflective layer between the clear plastic plates that make up the disc deteriorates. I see no reason to think CDs or DVDs would be immune to this degradation.