Network and Information Services

CD Burning Information and Tips for Data Retention

General Recommendations:

Choose a more expensive archival quality CD for data that must last over time.
Use a high quality CD burner and update the burning software/firmware on a regular basis.
Pay attention to storage and handling. Don't expose discs to direct sunlight or extremes in temperature.
Read and test the CDs for errors after burning.
When archiving data, it may be wise to burn the data to two CDs - one as a working copy and one for off-site storage.
The glue on sticky tape and labels can eat into the writing surface of the CD, damaging the data - special CD marker pens or blanks that you can print on directly are better options.
Hardware and software are constantly changing and burnt CDs don't last forever - plan a conversion and re-burn cycle for your data and CDs.
If disposing CDs, be aware of sensitive data that may be stored on them - be sure to make them unreadable. CD destroyers are available which can destroy both the top and bottom surfaces of the CD rendering the disc unreadable.
CDs that become unreadable can make excellent drink coasters, mobiles, or wall decorations.

Vendor Information:

*Caveat - this is not meant to be an endorsement of a manufacturer, brand or vendor but only examples of what we have found available. It is always advisable to do additional research and testing.

Archival quality CDs

Vision Business Products

Mitsui Mam-a-Gold CD-R

Part #00043016/80 min.
$82.00 for 100

Link to the Oregon State Archive web site for Records Retention information:

www.archives.sos.state.or.us/banners/recmgmt.htm

The Text Behind the Recommendations

While it is possible to burn data (or music, etc) to CDs very cheaply, it is very important to consider the type of data and reason for burning it to CD as well as the quality and storage of the CD itself.

CD durability:

The issues involved in the longevity of the CD media are scratches, extended exposure to sunlight, and extremes of temperature. The lesser quality CDs are more vulnerable to all these points. In addition, re-writable (CD-RW) discs are more vulnerable to temperature issues than recordable (CD-R) discs.

Manufacturers have stated 70 to 300 year life spans for their CDs but in reality any disc would be hard pressed to last that long. Also, finding hardware and software to read the disc after a number of years will be problematic thus limiting its useful life. It is not enough for the media to have survived error-free for several decades if there is no technology that has survived to read it.

Some glue used by CD labels has been known to react with the top coating of the CD and impact the reflective surface introducing errors.This may also be the case with some marker inks when writing on the top surface.

Silver vs Gold and the dye question:

There are two basic components to a CD-R, the reflective surface, which can be either gold or silver, and the dye formulation which is either cyanine or phthalocyanine.The laser interacts with the dye, heating it, creating pits in the polycarbonate of the disc thus writing the data.

Most CD-Rs use a silver reflective surface since silver is less expensive. Silver, however, can tarnish when exposed to air with the potential of reducing the reflectivity and increasing the error rate. Gold will not tarnish and is used on "archival" quality CDs.

Cyanine dye can be green to blue in color and is UV sensitive causing it to deteriorate when exposed to light. Phtalocyanine is clear to the eye and not UV sensitive. However, that is not the whole story - phtalocyanine needs a tighter laser power tolerance and generally works better at higher burning speeds, whereas cyanine works within a wider range of laser power and works better at lower burning speeds. Manufacturers are constantly changing dye formulations to reduce production costs and to optimize it for higher speed burners, so CDs may vary even within brand from one production batch to another.

CD burners:

Not only is having a good quality CD burner important, but also updating the software and firmware from the manufacturer on a regular basis.

To make the best possible copies using the CD burner, it is important to select the optimal writing speed and laser strength for the blank discs being used. This information is carried on each disc in the ATIP code. The CD burning software automatically reads this code and does a trial burn in a special area of the disc using tabled information in the software and firmware.

Each CD carries an ATIP code (absolute time in pre-groove) embedded in all blank CDs the gives the burner important information about the disc; its manufacturer, type (data or music - music CDs are often more expensive and slightly less vulnerable than data CDs), capacity, supported writing speeds, absolute lead-in time, the last possible position where data can be written, and how fast it can be burnt without undue risk of errors.

If the CD burning software does not recognize a new code (every batch, even from the same brand, could have a different ATIP code), it will burn the CD based on defaults which may not be optimal and potentially introduce errors.