• CD
• Korttiboxit
• Digipaino
• USB Tikut - Kopiointi - Esipainatus
• DVD
• DVD Studio
• CD-R / DVD-R esipainatus
• Musiikkipromot ja CD-R/DVD-R -kopiot

Verbatim-testin tulokset

Article in German magazine c’t about Archive-DVDs

"Data for Eternity" - Silver memories - Archival DVDs in a long-time test

Brief: The German computermagazine c’t (very reknown for technical and accurate information, >500,000 copies sold bi-monthly) tested DVDs based on the new specification ISO10995 / ECMA 379 defining such test. They recommend Verbatim Archival Grade DVD-R because it lasts 4 times longer than any other tested disc.

5 different DVD media were tested:

• Kodak Gold DVD-R
• TDK Scratchproof DVD-R
• Verbatim MediDisc DVD-R
• Verbatim Archival Grade DVD-R
• Taiyo Yuden DVD-R

The first part describes why DVD-R media were tested

They can be stored separately from the burner device. Stored data cannot be altered later on.  test methods for the recorded quality are available.  CD-R is too small. BD-R is too young and many changes for the recording layer and disc design expected over the next months/year. DVDR DL might create problems reading back mainly the second layer in some drives, independent of the recording quality. DVD-R is mature technology with well known manufacturing under tight control. A lot of experience with this media has been gained in the last couple of years. DVDRW media is less sensitive to UV-light, but the laser must be calibrated very accurate against the temperature specifications of the media. Due to the small market share this is often a bit neglected by the drive manufacturers. DVDRW media tested by c’t in previous tests shows unacceptable high error rates.

The second part describes why the tested discs were selected

Price is an important factor. So many manufacturers now manufacture in Asia due to price pressure. Testing inexpensive media from no-names or even some known brands does not mean anything, because those brands vary the sourcing of their discs, so different media is often sold in the same packaging. People selecting DVD-R for archival purposes must rely to get high-quality media again and again. Some manufacturers fulfil this demand, and quality has once again become more important than price. For this test we concentrated on well-known brands who market their discs with long archival lifetime.

Kodak markets their golden DVD-R with an archival life of more than 100 years. However, the reflection layer used by Kodak is NOT 24 carat gold, but an alloy of gold and silver mixed with other ingredients, because pure gold would not reflect light sufficiently.

Verbatim does not use pure gold in its Archival Grade DVD-R, but uses 2 layers: a silver layer on the data side for best reflection and drive compatibility, on top a gold layer for added resistance against the bonding glue. According to verbatim those discs are only manufactured on selected manufacturing lines that are proven to have low error rates. For archiving in the medical sector Verbatim offers their “MediDisc”. This does not have a gold reflection layer. The “MediDisc” complies with the regular Verbatim DVD-R, however, much tighter manufacturing tolerances are applied.

Fourth we tested TDK’s Scratchproof DVD-Rs. this differs from their regular media with an added scratchproof lacquer on the data side. Such added Hardcoat lacquer can also be found on Verbatim’s “Archival Grade” DVD-R. Whilst Verbatim uses an “AZO” recording layer, TDK uses Phtalocyanine based lacquer.

For comparison we added as fifth selection regular DVD-R from Japanese manufacturer Taiyo Yuden. We regularly use those discs for our tests due to their good burn quality. Taiyo Yuden’s discs do not have any scratch protection and use a cyanine based recording layer. Taiyo Yuden does not have its own brand here and supplies mainly B2B. be aware that a lot of fake discs with their mediacode exist.

The separation of disc and drive of course adds some uncertainty. For judging the quality and longevity the complete system must be tested, meaning not only the media itself, but also the recording device (burner) and the playback device (the DVD read out drive). So for judging the quality, both drives must be added to the test.

This background explains, why marketing statements like 100 years lifetime are not to be taken serious. For stating such, the burner, reader and the storage conditions must be exactly defined, which is not be done by the manufacturers.

The testing

The standard ECMA 379 defines a test method for measuring data archival life. For this test media is stored for months in climate controlled chambers. For lifetime extrapolation ECMA uses formulas from Svante Arrhenius and Henry Eyring. Those formulas state that chemical reactions are faster in warmer and more humid environment. However, testing is extremely intensive when using ECMA 379: Per media type 90 discs must be tested for 9 months at temperatures between 65°C and 85°C and relative humidity between 70% and 85%. The discs must be tested every 250 hours. Just for this laboratory costs of 40,000€ per disc type must be calculated. So this testing is done only seldom. Even Verbatim and Kodak have not yet finalized their tests.

For getting the lifetime the time is interpolated that discs use to reach the error limit  PI Sum 8 of 280. When the time is known at the high temperatures, then the lifetime at office environment can be interpolated logarithmically. Every climate controlled chamber will test minimum 20 discs of one type, so statistical methods can be sued. Average gives the time at 50% failure rate, meaning 50% of the discs reach the error limit giving the risc the discs cannot be read back anymore. This is also often used by the manufacturers. For planning an archive this is not important. Here the second value given by ECMA should be used, when 95% of all discs under test can still be read and only 5% fail. When this criteria is used, then all DVDs have zero lifetime when 1 of 20 burns fails.Aas our previous tests have shown, only very few drives and DVD discs are better than that from beginning onwards.  Anyway, the results are theoretical values wqith ideal storage conditions and specified test drives. In tropical environment discs live shorter, in a dry cellar probably longer.

For our test we simplified the ECMA test. we only used 6 discs per media type (instead of 20) that were burnt  in 6 different burner frm ASUS, LG, LiteOn, OptiArc, Pioneer and Samsung. We recorded all discs at 8x speed. the discs were tested directly after recording . They they were stored in climate controlled environment  of 85°C and 85% rh for 100 hours, taken out after the defined cooling process, tested and stored back again. This was repeated over and over again until the discs failed. Then we interpolated the time until the discs reached the error rate of PI Sum 8 of 280.

The result

According to our tests the KODAK media failed first. Already after the first 100 hours all discs were unreadable. This means the so-called gold discs are defective after 11 hours. from 18 Kodak discs already 4 failed directrly after burning. So lifetime is zero according to the strict ECMA criteria. It should be noted that the Kodak DVD-R did not reflect enough light despite their gold-silver alloy. instead of the specified 45% the discs only reflected in average 239.7%. After 100 hours in the climate chamber, this value became only 30.5%. This points to the assumption that the reportedly so robust alloy reacts with the other layers. We confronted the distributor of these discs (which are manufactured in Moser Baer India) with these results. According to them the discs were only tested in 70°C environment, which is way below the ECMA standard of 85°C and even below the older standard ISO 18921 of 80°C. At 70°C those discs would have had 500 hours which is 100 years. However, Kodak did not show us their test results nor their interpolation. They could not explain the low reflectivity.

The second worst were the TDK discs. that survived 11 hours on average in the climate chamber. This is 10 times longer than the Kodak discs. The Verbatim MediDisc survived on average 235 hours. Best values were achieved by the Verbatim Archival Grade DVD-R with 558 hours and the Taiyo Yuden with 638 hours. However, please note that the Taiyo Yuden discs had a much bigger variance in the results. The first Taiyo Yuden disc failed after only 85 hours, whilst the first Verbatim Archival Grade only failed after 322 hours.

Further discussion

With our testing we cannot yet define lifetime in office environment. Further testing is necessary and undergoing. Those tests will be finalized in 2009. So we can now only assume the disc lifetime. Within the EDCMA specification a factor of 500 is used for an example, meaning discs would live 500 times longer at 25°C and 50% rh than in 85°C and 85% rh. This means Verbatim Archival Grade DVD-R and Taiyo Yuden would last more than 30 years, whilst Kodak Gold DVD-R would be defective after only 8 months. Older test results from Verbatim and Sony use factors of 2000. Using those factors the Kodak would last 2.5 years, the TDK 25 years, the Verbatim MediDisc 54 years, the Verbatim Archival Grade 127 years and the Taiyo Yuden 146 years. The truth is probably somewhere inbetween.

Burners only have an astonishing low influence to the media lifetime. Though the Asus drive gave the worst recording quality directly after burning, the media lasted on average longer than with the Optiarc than had initially the better recording quality.

When archiving discs, they should be tested in regular intervals. We cannot recommend using the Kodak media at all. TDK media should be tested at least every 3 years, Verbatim MediDisc and Taiyo Yuden every 5 years. However, we recommend testing latest every 2 or 3 years. Using Verbatim Archival Grade DVDR you might even take 18 years for the first test. Doing a cost calculation , this means the initially more expensive Verbatim Archival Grade DVD-R become the least expensive over the years.

Final review

If you plan to archive your data on DVD-R, you should carefully select the media you use. Advertising 100 years cannot be taken serious, as the example Kodak shows. But, media need not last 100 years. probably you will need to migrate after 10 or 15 years because of a change in your system or hardware lifetime. Whether there are rotating media in the year 2023, we do not know. However, until then Verbatim Archival Grade DVD-R give the best security for your data of all tested media, because it last 4 times longer than any other disc.