----- Original Message ----- From: "Dan C" : What about lengevity issues? If properly stored, which of DVDs or CDs will : last longer? I went through this exercise some time back, here's a bit of info I came up with.. It seems there are two separate issues with CD's DVD's regarding how safe they are for storage - compatibility and reliability. Compatibility is a fairly important issue, but nothing like reliability - even though on the surface people often seem to mix the two up. If a CD-R or DVD+R doesn't work in a machine often it's assumed the disks are no good whether they are or are not, and when people achieve a successful burn that they can read back afterwards they assume reliability - again a false assumption. Reliability is more a numbers game relating to the number of errors, but not just the errors inevitably written or read from a disk at the time it was burnt but more - do more errors develop over time? Part of the error related issues goes back to the dyes used to record the information. In a recent discussion someone was suggesting that they only used TDK's, my suggestion that another brand might actually provide better security was met with the sort of scorn only edu-marketing hype can instil in someone, so I had a bit of a look around to see what dyes were used in manufacturing various disks.. the most durable dye, PhthaloCyanine, used in Princo's and many other makers too, but I found the TDK's listed were using cyanine dye(what!!!) - the worst dye of the lot for longevity - and they use this in the disks that they *guarantee for 100 years* even though the dye has through testing shown to have an expected survival period of around 10 years. Now not all the TDK disks were made with this cheaper dye, but hey, something funny going on here :-/ Sounds like the marketing department has it all over the engineers! The other thing that was very strongly related to failure rates is the reflective surface used and how it is protected. CD's and DVd's have a shiny coating of silver, aluminium or once upon a time gold against which the laser bounces the light back to the reader/writer. If this layer dulls or is damaged, so long data! Aluminium is most often used for it's high reflectance but it is also highly reactive and needs protection from the elements. A badly coated or damaged backing WILL in time allow the reflective layer to corrode. Even silver eventually is attacked by oxygen and moisture and again, damage results, even stresses such as flexing a disk can cause the reflective layer to shift, delaminate or draw in air.. again, damage will be the end result. If this reflective layer was sandwiched in between something more stable then the chances of the reflector suffering damage or corrosion is reduced - enter the DVD - same as a CD really but with a closer groove but with an additional polycarbonate sandwiched to the back for added dimensional stability and protection :-) regarding polycarbonates tendency for absorbing water (allowing corrosion of the reflective layer to occur quicker) - storing CD's and DVD's with SilicaGel or something similar to reduce the humidity is probably a good idea in the long run. Finally, of course, burning them SLOW to minimise errors (and errors DO occur on just about all burns) is a really good idea. the error correction that takes place when reading CD's DVD's will allow successful reads on an error riddled optical disk for quite a while before the error count on a poorly burnt, badly stored or damaged disk goes too high and the data becomes unreadable My experiences (and I've burnt literally 10's of thousands of CD's and probably 8 or 9 thousand DVD's) leads me to pick DVD's over CD's Back to the TDK Vs Princo issue - Years ago I bought 5 TDK Pro SAX-60 recording audio tapes for around $20 each (top dollar back then!) they've all stretched and they all wow like crazy, they all have a hideous hiss and they all sound dreadful. I also had a Sony moderately priced UCX-90 $6.00 tape given to me which spent most of it's life in my hot box, matte-black charger. it's still crystal clear after all that abuse .. it's 23 years old now :-) that was one of the first lessons I had in discovering $$ spent does not equate to quality received. Makes sense though, a company that spends squillions on advertising probably has less to give their R&D dweebs. Nikon learnt this same lesson in the 70's when the marketing gurus were getting truck loads of cash to splash 'Nikon' across every available flat surface while their lens designers were having to burn chairs for heating. They all quit since they were PO'd that they couldn't bring any of their innovations into production and started the Tokina company and took all the good designs with them. I think the *best* way to resolve the which disk brand /type is best question is to check the error count on the various disks available and then treat the results as a guide*. Compatibility is NOT a good guide to reliability, only the error count gives a true indication of fallibility. *like film, every batch is different and because one review says their lot tested good doesn't mean the batch I buy tomorrow are also going to be as good The burners themselves can be responsible for disastrous burns too, not just the disks. My first LiteOn burner was a pig (I discovered later down the track). It burnt away happily and gave me lots of shiny disks which read fine for ages, then the burner blew up. I bought another and found NONE of those original disks were readable.. in ANY OTHER BURNER I moved to an LG burner for the DVD RAM capability and because I've had the least errors both in compatibility and reliability of the resulting burns. I've been through 2 pioneers and 3 LG DVD burners now, both have been good but I'd go the LG - hey, DVD RAM - :-) For those interested in actually testing their disks rather than trusting reviews or references there's a few tools to use: kprobe: from http://www.cdrlabs.com/kprobe/index.php (2.1Mb download) allows you to test dvd's by looking at the errors on the disks. and http://www.dvdinfopro.com/ The program provides information & tools for DVD-R/RW, DVD+R/RW burners, DVD+R DL (Double Layer) burners, DVD-ROM players It also provides information on CD players & burners. Current version v3.52 17/02/2005 http://www.dvd-recordable.org/wwwimgs/media/flash/dvdinfopro/dvdinfoproadve rt.zip Free Version with embedded adverts 1.59meg. www.DVDrecordable.org - a good site for reviews on optical media and drives outcomes and experiences of testing have been listed here: http://www.videohelp.com/dvdmedia princo AND TDK DVD's (and others) scored a GOOD rating, interestingly there are substantially more user comments, most very good, on Princo than the nest nearest commented upon brand.. 297 V 74 comments seems that the reviewers also get to state how many disks they've burned too - some of the reviewers have burnt a mere _single_ disk on which they've based their reports - the Princo brigade however all seem to have burnt 25, 100, 50 etc . from CDMedia world - the gos' on TDK's.. some of which are even MADE by TDK <!?> http://www.dvdmediaworld.com/hardware/cdrom/tdk.shtml and other brands.. http://www.dvdmediaworld.com/hardware/cdrom/dvd_info.shtml some stuff about quality http://cdmediaworld.com/hardware/cdrom/cd_quality.shtml and dyes.. http://cdmediaworld.com/hardware/cdrom/cd_dye.shtml k
