Discussion in 'Computers, Hardware, and Operating Systems' started by K2WH, May 8, 2019.
Yup... New thumb drive every few years. I think my latest is 32G. Probably time for a new one soon.
Those are pretty inexpensive; Just (IMHO) go with the USB 3.0 drives; the USB 2.0 are "kinda" outdated, but are a bit less expensive. The speed is the big trade-off. 64 and 128 GB thumb drives are available, but in some (most?) circumstances, that is "putting all 'eggs' in one basket.." 32 GB is a "sweet point," at least at this point in time.
Data retention on flash memory is good for at least 10 years, unless there is a highly unusual event, like cosmic ray spallation. CDs are the LEAST permanent means of storage, they're prone to bit rot by both light and heat. DVDs are less prone to physical damage, and the re-writable versions are MUCH more permanent than the non-RW discs. DVDs can store only 4.7GB, that's not very much capacity in today's world. Magnetic (rotating) hard drives and flash memory are currently the most dependable means of data storage, but no device is completely safe from data loss. Make multiple back-ups and store at least one copy at a friend's or relative's house. Personally, I don't trust cloud storage, no matter how much they promise to be "secure".
Why is that ?
Seems that write slow once would be more reliable.
Non-rewritable CDs and DVDs use a recording layer that is similar to photographic film, it's a chemical that reacts to light. That chemical reaction is not reversible, hence the disc can't be erased and re-written. However, the portions of the recording track that were NOT exposed to light are still light-sensitive, they can still be changed by exposure to light (or heat). When a disc is "finalized", this does not prevent further chemical changes, it merely writes a file to the disc that tells the optical drive that the disc is used and can't be written to again. The laser that is used to read a non-rewritable CD or DVD will also slowly damage the data on the disc, it's a cumulative effect.
Re-writable CDs and DVDs use a metallic layer to record the bits (1s and 0s). Some metals can exist in two different crystal structures at room temperature, depending upon how fast they are allowed to cool from the molten state. Re-writable CDs and DVDs require the heat that is generated by a sharply focused laser to melt the metal of the recording layer and re-solidify it in one phase (crystal structure) or the other, depending upon whether it is writing a "1" or a "0". When the disc is read by the laser, the different crystal structures reflect different amounts of light that correspond to the "1s" and "0s" that were originally written to the disc. Placing a re-writable CD or DVD in sunlight, or exposing it to heat (unless the heat is hot enough to melt the plastic substrate) will NOT melt the metal of the recording layer and damage the data that it contains. Short of destroying the entire disc, the only thing that will change the data on a re-writable optical disc is the laser in a CD/DVD writer. These properties are the reason that the RW disc can be "erased" and "re-written". Turn up the power of the laser, melt the data that has been recorded, and write new data in its place. Also, the laser will NOT damage the data on the disc during the "read" operation, because it doesn't heat the metal recording layer to its melting point.
Take a non-rewritable and a re-writable CD or DVD with data written to them, and place them on the dashboard of your car, exposed to the sun. Leave them there for a few days. I guarantee that the data will be damaged on the non-rewritable discs, and the data will be undamaged on the re-writable ones.
Extra info: the recording layer on a CD is on the underside of the label, where it's prone to physical damage if the label is scratched, etc. Take an old CD and break it, you'll see that it is one single piece of plastic with a label on it. Take an old DVD and break it. There are two discs, with the recording layer protected between them.
Extra extra info: DVD+RW is superior to DVD-RW