DVD media 4

[lgvelez]

If I get one of the new DVD 8X double media, can I use any type of dvd media? Is the new one backwards compatible? I have a package of DVD+R 4.7 gb 4x ... will that work okay with it?

This is my first upgrade from a CD recordable drive.

Thank you, Laura

Laura Velez, MCP
lauravelez@charter.net

 

[stduc]

Remember your basic school physics. A changing magnetic field will induce electical currents in a conductor. Thus, placing one near a loud speaker will induce currents in the alumininium layer of the disk. This will cause it to heat up. How much will depend on the power of the loud speaker and how close to the coil the disk is. Placing it on a bar magnet will have no effect.

What you must remember is all optical media (CD's/DVD's) consist of a layer of aluminium that is only a few molecules thick + various optical dyes layed down on a plastic base and sealed with resin. The resin coat is also very very thin.

Heat can warp the disc. The laser then won't focus on the tracks and the disk will be unreadable.

The ultra violet light in sunlight will eventually bleach the dyes - making the disk unreadable.

If there is the slightest pit or scratch in the resin coat, oxygen from the air will eventually get in and oxidize the alumininium - making the disk unreadable.

Human sweat will eventually corrode the resin coating. Allowing oxygen to oxide the aluminium - making the disk unreadable.

The processes of decay are temperature dependant. The hotter it is, the quicker the decay goes.

Any combination of the above factors will ultimately destroy an optical disk. The trick to a long life is keep them clean, cool and in the dark.

Better quality disks probably have a better resin coat - hence they last longer.

 

[jurgen36]

stduc:
Yes you are quite correct. Here in the trophics with a very high humidity level in unairconditioned rooms cd's do no last a very long time. Pressed Cd/dvd's seem to be pk. But cdr's usually last only 1 or two years. It does not seem to matter from which manufacturer thei are. The whole paint layer with the printing lifts off in patches, that way the burned tracks are not protected anymore. We sometimes can recover data by using self sticking alu foil and cover the cd. cut the excess of, etc. it seems to work ok, but not always. A German computer magazine did run some accelerated life tests with data cd's and found that most of them started to loose data after 6 to 9 months. The best with data retention were the golden colored Princo cd's. Normally the user would not notice it as the data recovery build into the drive takes care of it. However once there are too many errors it cant do the job anymore and the cd fails. We do our importand data backup on portable hard drives using tripple redundency. We originally lost some of our data backed up on CD's.
Regards

Jurgen

 

[pmonett]

Hey, stduc, that's a great reminder and a nice, easy list of Things Not To Do with optical discs.

Have a star !

Pascal.

 

[stduc]

[blue]pmonett[/blue] - Thanks, appreciated.

[blue]jurgen36[/blue] - I didn't realise it was such a problem in tropics. Thanks for the info. Have you ever considered keeping your disks in the fridge in a ziplock bag, maybe even with a packet of silica gell inside. If you keep those little packets of silica gel you get when you buy items like new hard drives you can re-active them in the oven at 100C - until the crystals turn blue. When the crystals can extract no more water from the air, they turn yellow/pinkish. You can re-active the crytsals as often and as many times as needed.

 

[cdogg]

stduc,
That is excellent information! I did not realize that a changing magnetic field affected the aluminum layer like that. Have another star!

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[garebo]

Seems what i read then likely did happen the way it was described.




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