News and recommendations

Congresses

You will find us at following congresses:

Medica 2008
Düsseldorf
November 19 – 22, 2008
Arab Health 2009
Dubai
January 26 – 29, 2009
35th Annual Congress of Gesellschaft für Neuropädiatrie
Graz
April 23 – 26, 2009
DGN 2009 – 82th Annual Congress of Deutsche Gesellschaft für Neurologie
Nürnberg
September 23 – 26, 2009

Data archiving

Life expectancy predictions for CD and DVD media vary between several and hundreds of years – dependant on the test methods used.

Each time, an optical disk is used, its life expectancy is shortened. Beside mechanical stress and dirtying temperature, humidity and light exposure affect the life expectancy of optical discs.

A study performed by the National Institute of Standards and Technology (NIST) found huge differences between life expectancy of CD/DVD media depending on the dye types used in the media. NIST found CD-R media with phthalocyanine (gold CD-Rs with a greenish yellow colour) more stable than CD-R media with cyanine and azo. Since there is varying proprietary modifications made to the dye formulations for DVD-R, which are less accessible than for CD-R, NIST could not make make a determination of DVD-R stability based on dye.

According to experts, life expectancy of optical media cannot be estimated by relying on brand names. A cheaper no-name product can be as reliable as an expensive brand product. Leading manufacturers could modify production methods with negative effects on media stability and reliability as well as small manufacturers could. Also, according to experts, there are bad gold CD-Rs and good non-gold CD-Rs.

Walter Graphtek recommends:

Do not use DVD-RW media as storage medium, since lifetime of these discs is unpredictable.
Do not use CD-RW media, since the alloy film used in these media is not as stable as the dye used in R discs.
When using CD-R or DVD-RAM media: Copy the data onto two disks. Use one for re-use, and the other for archiving. Handle the media used for archiving according to the NIST Quick Guide for Care and Handling CDs and DVDs.
Consider deploying the PL-Winsor Archiving option, which uses hard disks instead of optical media. Data safety hereby is achieved by the backup prodedure: short backup intervals in combination with an exchange of hard disks as soon as unreliable behaviour occurs.

Further information

Council on Library and Information Resources: Methods for the care and handling of CDs and DVDs
October 2003. With very good explanations.
Wikipedia: CD-R
Wikipedia: DVD-RW
Wikipedia: DVD-RAM
National Institute of Standards and Technology: Stability Comparison of Recordable Optical Discs—A Study of Error Rates in Harsh Conditions
Volume 109, Number 5, September-October 2004 - Journal of Research of the National Institute of Standards and Technology
Empfehlung der Technischen Kommission der Deutschen Gesellschaft für klinische Neurophysiologie und funktionelle Bildgebung (DGKN) zur Nutzung von CD-ROM-Medien für die Archivierung digital erfaßter EEG-Daten
German. 1999.