1. What is the average lifetime for a standard CD (industrially pressed and self-burnt)?

Tests on expected storage life conducted in house using climate chambers show a durability of approx. 100 years, both for CD-R and DVD-R. This applies to discs stored under certain conditions, with the original burning quality naturally also playing an important role. In that respect, there are preferred burner/media combinations. The method of storage also plays an important role (upright in a jewel case, at approx. 20 – 25°C and 55% relative atmospheric humidity, protected from light, smoke-free etc.).
Each use of a CD-R/DVD-R will normally shorten its useful life, as minor damage such as scratches, fingerprints, dust etc. is difficult to avoid. Careful handling of media is therefore advisable to prolong the discs’ working life. Given the direct influence that the user has, however, no fixed period can be given here.
We cannot comment on the working life of pressed CDs/DVDs, as we have no test data. With a similar quality of manufacture, however, they should last as long as writeable media.

2. Based on current knowledge, how long will a standard DVD last (industrially recorded and self-burnt)?

see question 1

3. Why are there differences in the storage life of CDs and DVDs (technical explanation)?

Our tests on our media show no differences.

4. In terms of how long a disc will last, does it matter what data is stored on a disc (audio or other data files, e.g. programs)?

With DVDs, in principle, no, as saving always takes place using the same format system, with error correction. With CD-Rs, there are a number of recording formats that vary in the depth of their error correction, meaning that differences are possible. Data CD-Rs use error recognition and error correction procedures that audio CD-Rs do not possess. The data itself plays no role.

5. What’s the main reason for data loss (technical background, composition)?

A CD/DVD is made up as follows: on a substrate of polycarbonate the writing layer is put, with a metallic reflection layer added afterwards. Both these layers are sealed with a fourth layer of special clear varnish on CD-Rs or bonding glue on DVDRs (see drawing). The media is written to and read using a laser beam that shines through the plastic substrate to the recording layer and is beamed back by the reflective layer.
There are many reasons why media may become unreadable. These include, in the first instance, damage caused by the user through scratches, fingerprints or other day to day handling damages. In second place, inappropriate storage - e.g. in a car (heat) or in direct sunlight - plays an important role, causing the recording layer to decompose. Thirdly, the original burn quality is often insufficient, due to faulty burners, unspecified or too-high burn speeds, makes of media that have not been tested by the burner manufacturer, etc. Faults in the manufacture of the media can also play a role. These include inadequate sealing, allowing atmospheric oxygen to reach the recording/reflective layer, causing it to decompose/corrode (rust).

6. What is particularly damaging in terms of the potential working life of optical media (light, dirt etc.)? Does the colour of the disc also play a role and, if so, why??

Light, heat, atmospheric humidity, scratches and dirt all play a role in determining wear.
The colour of the recording layer plays no role. It is merely an indication of the chemical substance used in the recording layer. Invisible to the customer, the differences lie in the quality of this substance itself, which can vary greatly.

7. What’s the situation with durability for new high-resolution storage media such as Blu-ray Disc and HD-DVD?

Our tests on their storage life are not yet complete. Results to date suggest that they will have a similarly long working life.

8. Are hard disks and USB sticks an alternative for storage or are they threatened by long-term deterioration or data failure as well? If so, after how many years?

The storage cells in USB sticks hold data for a maximum of 10 years without recording the data again. Apart from their price, therefore, they are not an alternative solution for long-term data storage.
In principle, hard disks can store data for longer. Given the moving parts they contain, however, they are more susceptible to failure. Then there is the fact that technical advances in hard disk controllers are occurring at a very fast rate, meaning that after a few years there will often be no compatible controller hardware available for reading them.

9. In your opinion, which currently available storage media is the most stable in the long term?

For standard applications, we recommend the redundant storage of important data on DVD. Discs from different batches or from a range of manufacturers should be used. As in professional storage, media should be checked for quality after burning and at regular intervals.

10. How will people store important data in ten or twenty years? Is the eternal storage solution already a possibility?

This is also a subject constantly being discussed in the archiving industry, though without a conclusion. CD-Rs have been in use for around 15 years now and will certainly continue to be used for another couple of years. Recently, sales of DVDR exceeded those of CD-R in Europe for the first time, meaning that DVDR is likely to continue to be the most economical storage medium for the foreseeable future. In professional circles, magneto-optical media, UDO devices or tapes are also used. Data is regularly migrated, i.e. copied over to the next, most current storage generation.
As a manufacturer of storage products, we naturally conduct ongoing research into new media. Whether Blu-ray Disc, HD-DVD or holographic media will become established cannot yet be predicted.