DURATION OF CDs/DVDs

Published September 4, 2012 by Tony

RELIABILITY AND DURATION OF STORED DATA

Although I am not that old, during my short life I have seen a number of technological changes in electronic data storage.
I was just a boy when the audio-cassette (musicassette) began to take the place of the bulky Stereo8 cassettes. To listen at their preferred singers many people had to buy again any LP in the new audio format. 

A few years later I happy attended at another major change, the arrival of VHS, which replaced the fragile Super8 film. This format was so successful that in the world the VCR is considered the most common unit after TV or fridge!
Also the video cameras adopted this new system, at the expense of Betamax and Video8 system, both by Sony. To create devices more manageable, VHS became mini-VHS  (VHSC), though similar technical characteristics.
I think because of these changes a lot of people lost many old cherished memories recorded on film, except those who, for cognizance or randomness, were able to transfer their videos on VHS cassettes, either alone or through specialized laboratories.
Who knew that after 20 years things would change again!?
Today, VHS and VHS-C have disappeared, replaced by plenty of DIGITAL media storage and devices:  CDs and DVDs, Blue-Ray, digital cameras, DVD players and recorders represent the current digital technology.
Even the photographic film, we thought to be immortal, has been definitively replaced by digital storage media.
It all started with computers, of course, because digital media are born to “store” data through the computer. But, also if about technological innovations, the computers and the digital method are newcomers, in their short history they already count “dead & missing”, in terms of digital media supports, software and hardware. If we are out of step with the times, any IT-based device becomes obsolete and useless in few years.
For those who do not know it, the early medium data storage was the popular floppy (5 1/4 and 3.5 inches). In a short time this media was substituted with the arrival of more capacious hard-disks, and then wit optical disks – CD – that could contain up to 700 Mbytes of data.
But again, time and money wasted, because two years later the DVD system  appeared, with its 4.7 GB of free space, then joined by Double-Layer (double capacity) and Blue-Ray.
And what after the DVD time?
Who knows, time will tell!

Conclusion?
If in the 60s Mr. Tom had recorded his “memories” on film, in the 80s, to not lose them, he was  obliged to digitalize and copy them (by a lossy conversion) on VHS cassettes. Then later, if he wanted to keep up with the times, he had to digitalize and copy them again using the new DV format, also if  soon after, to be sure to see his “memories” in the future, he had to recode the whole thing and burn it on DVD (through another loss of quality). In 40 years are changed three methods of recording and, beyond the degradation of the analog (magnetic) system due to the passage of time, the transformation of the video in different formats inexorably worsened the final quality, despite the characteristics of the DVD media boast best quality.
Mr. Dick, instead, who had kept his data on floppy disks, was forced to pass them on CD and if wishing can record them on DVD today, but here, despite the fact that at bit level there is no loss of quality (or of the data), we must consider more important factors, which is the operating system (OS) and the software overall. Because at the level of operating systems over the years, the changes have been significant and radical.
DOS, Windows and Linux to name the most widely Operating Systems used around the world. A program created for the DOS environment, no longer works on devices that operate under Windows Vista or Windows 7, for example. The same, of course, will happen in the future with what is happening today. Nothing is certain.
I shudder and am taken by a strong discomfort in thinking that primitive men have given us signs engraved on rocks that have stood for over 2000 years, while after 5000 years even an ancient Egyptian inscription on papyrus is still perfectly readable!
Today, instead, after only 40 years and many troubles, Tom finds himself with data strongly degraded and the risk of losing them in a few more decades. Dick, instead, can’t have easily access to his digital data stored no more than 30 years ago.

Despite yellowed, in old album I still find, with pleasure and satisfaction, photos taken more than 100 years ago from my ancestors, while among computers, peripherals, storage media and programs, I have lost a lot of data and digital information. How many times that damn “floppy’s track 0” has abandoned us, making data inaccessible, or how many times we had to deal with hard-disk or any CD unreadable due to some bad sector or because a defective FAT?
You can lose everything in a moment and without prior notice!

One wonders if this is a true technological innovation and what are the limitations to keep in mind.

The physical duration of digital media is not known with certainty, and aside from unexpected damages, it is certainly less than primitive men’s stones, papyrus or paper, if well kept. But as said, if the problem was only the duration of the physical support, then it would be sufficient in getting a new copy periodically, apart from the inevitable “oversight” that, in view of the “time frames” we are referring to, should not be underestimated. The real problem here, however, is the hardware. The digital media and its copy becomes useless if at the same time survives no player or machine (hardware) able to read them, together any programs (software) enduring, able to manage them. In general, the risk of persistence in time of the electronic documents are the following:
1 – Lack of physical duration for data storage media
2 – Hardware Obsolescence for decoding media
3 – Obsolescence of software for the interpretation of the data
4 –  OS obsolescence.
Unluckily, for the moment, there are no market strategies, because in this situation, they just are the IT companies to earn, and innovation lies both in terms of costs and risks on consumer’s shoulders.
Anyone who has had the opportunity to see a very old photo of his great-grandfather or, as me, to have a postcard sent by my father while in Germany during the world war II, is concerned that with the advent of the digital epoch,  his grandchildren can’t, in future, do the same with electronic documents preserved today.
Although I’ve already lost a lot of data, I try to make multiple copies of digital data that interest me more, as well as having already copied on CDs and DVDs some old VHS movie. This is not easy, and needs equipment and knowledge.

DURATION OF THE OPTICAL DISKS (and factors affecting it)

The physical duration of CDs and DVDs is not as long in time as commonly thought, or as indicated on some packaging.
For writable CD and DVD the manufacturers claim a life expectancy  5-10 years if still virgin, and even 100 years after the burning process, if kept and stored in absolutely optimal way, of course. However, some studies show that their life expectancy is considerably shorter, in the order of 25-30 years only, practically nothing in comparison with the PAPER!
Furthermore, the duration depends on many factors, the most important of which are the external aggressions from polluting/corrosive substances, the conservation and the physical damage of the surface.

ADVICES

Sunlight/UV exposure, humidity, temperature, some organic solvents reduce the disks life.
Deep scratches are another possible cause of disk failure.
Don’t use sharp pens and take into account that even the type of ink/dye used for general felt-tip pens can damage the surface.
Avoid to use sticky labels that cause imbalance in reading.
If you have to use the disks for backups or important data, avoid bulk or unknown brands, but focus on quality disks, even though they cost more.
Do not burn at high speeds because higher speed can increase error rate.
Use a reliable burning software and perform the check of the burned data.
From time to time, check the disk and after 5-6 years make a copy also if the disk still looks good.

Then, good luck!

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