Disc Quality
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Disc Quality
Hi
I have just transfered all my collection of films (approx 250) from VCR Tapes to DVD's. I am just wondering How long can you keep DVD's before the films quality starts to degrade ???
I have just transfered all my collection of films (approx 250) from VCR Tapes to DVD's. I am just wondering How long can you keep DVD's before the films quality starts to degrade ???
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How long can you keep DVD's before the films quality starts to degrade ???
But the hardware to read digital media typically degrades faster than the media, and the software degrades fastest of all. Saab Dastard is right.
There was an article on BBC Breakfast this weekend about the life of discs. They artificially aged them and found they vary from make to make & even those within the same box can have different life spans evidently.
They recommended transferring data at least every 5 years.
They recommended transferring data at least every 5 years.
Spoon PPRuNerist & Mad Inistrator
I didn't want to be alarmist, but I would agree that 5 years is a worst-case lifetime.
There is an order of magnitude difference in lifetime between the metal pressings in commercially produced discs and blanks for home use, and the higher the data density the lower the lifetime, as a general rule of thumb. Also, write-once are generally longer-lasting than re-writeable, due to the stability of the dye used.
So WORM CD-R blanks will last longest, with RW DVDs lasting the shortest time.
And of course, manufacturing quality needs to be considered, with some poor-quality media being little better than junk. But then most expensive doesn't always equate to best performance either.
The Dastard digital photo collection is stored on disk, backed up to disk (twice, once to another PC and also to external HDD) and then archived onto CD-R, as being the media with the best storage life (I hope).
SD
There is an order of magnitude difference in lifetime between the metal pressings in commercially produced discs and blanks for home use, and the higher the data density the lower the lifetime, as a general rule of thumb. Also, write-once are generally longer-lasting than re-writeable, due to the stability of the dye used.
So WORM CD-R blanks will last longest, with RW DVDs lasting the shortest time.
And of course, manufacturing quality needs to be considered, with some poor-quality media being little better than junk. But then most expensive doesn't always equate to best performance either.
The Dastard digital photo collection is stored on disk, backed up to disk (twice, once to another PC and also to external HDD) and then archived onto CD-R, as being the media with the best storage life (I hope).
SD
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As delta says (in fact the researchers said 4-5 years) don't wait because once it has gone............................the recommendation was also to either back it to hard or cloud as well.
I think it is appalling that DVD disks are so bad. The BBC (it ran on 'Click' as well) reckoned that even 'top' grade disks had bad batches. Why is it so difficult to produce quality?
I found a few DVDs that would just not read after 2 years a while back. Files appeared to be all there, but it would just not put it together.
I think it is appalling that DVD disks are so bad. The BBC (it ran on 'Click' as well) reckoned that even 'top' grade disks had bad batches. Why is it so difficult to produce quality?
I found a few DVDs that would just not read after 2 years a while back. Files appeared to be all there, but it would just not put it together.
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I wonder, is prolongued exposure to daylight a factor in shelf life?
Would storage in a dark place help, and if so, would storing unused media in the dark be a good idea?
Would storage in a dark place help, and if so, would storing unused media in the dark be a good idea?
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I'm stupid and don't remember the color of the "books", but the digital CD-R format is piggy-backed on top of the analog CD format. (for what that's worth)
A fellow down the corridor from me had a job investigating the archival quality of write-once and RW CD and DVD disks. As far as I know, he just use elevated temperature to speed aging. He could control humidity, so that may have been involved as well. Bright light is KNOWN to cause more-rapid aging.
The raw error rate of CDs is vaguely one error in a million bits - far too bad to be useful. Various redundancies and error correction are built into the recording standards.
As disks age, they have more and more errors until the number and location of errors becomes too great for the error correction to handle. One needs to transfer the data onto another disk before that happens. Note that you want to copy the __files__ while error correction can still fix the errors. Sector-by-sector, track-by-track disk duplication will just transfer the errors to the new disk! BAD!!
Some CD and DVD drives and their reading software can report how hard the error correction is working to repair the errors on the disk being read. Keeping track of this information gives a better measure of how each of your disks is degrading over time. Unfortunately I don't know which drives and software have this feature - though the fellow gave me a Plexstor software disk. I haven't tried it.
A fellow down the corridor from me had a job investigating the archival quality of write-once and RW CD and DVD disks. As far as I know, he just use elevated temperature to speed aging. He could control humidity, so that may have been involved as well. Bright light is KNOWN to cause more-rapid aging.
The raw error rate of CDs is vaguely one error in a million bits - far too bad to be useful. Various redundancies and error correction are built into the recording standards.
As disks age, they have more and more errors until the number and location of errors becomes too great for the error correction to handle. One needs to transfer the data onto another disk before that happens. Note that you want to copy the __files__ while error correction can still fix the errors. Sector-by-sector, track-by-track disk duplication will just transfer the errors to the new disk! BAD!!
Some CD and DVD drives and their reading software can report how hard the error correction is working to repair the errors on the disk being read. Keeping track of this information gives a better measure of how each of your disks is degrading over time. Unfortunately I don't know which drives and software have this feature - though the fellow gave me a Plexstor software disk. I haven't tried it.
Warning! Rumour follows:
I seem to recall reading somewhere that disks written at a slower / slowest speed (where you are given the option) are more likely to retain their data over a given period of time than those written at Vmax . It's beyond my capability at this time of day to recall the reasons, if indeed there were any
.
Pity, we all thought we were on to a good long term storage medium when they first appeared. Still it's good for the sales of external Hdds.
SD's policy is the wisest option.
FoR
I seem to recall reading somewhere that disks written at a slower / slowest speed (where you are given the option) are more likely to retain their data over a given period of time than those written at Vmax . It's beyond my capability at this time of day to recall the reasons, if indeed there were any
.Pity, we all thought we were on to a good long term storage medium when they first appeared. Still it's good for the sales of external Hdds.
SD's policy is the wisest option.
FoR
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The question was about DVD's. Generally the CD lasts much longer, but I suspect the mad greedy rush to capitalise on the DVD market has led to short cuts in production quality.
Beware - even 'branded' disks sometimes are not.
Beware - even 'branded' disks sometimes are not.
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My daughter unearthed a photo of her great-great-grandmother the other day. It was taken in 1880-something and printed in sepia but was still perfect in all the relevant details. She scanned it and printed it out on her colour laser printer, as well as saving the .jpg to hard disk.
We're taking bets as to which - original sepia, colour laser, or .jpg will last the longest starting from now. Anyone care to arbitrate?
We're taking bets as to which - original sepia, colour laser, or .jpg will last the longest starting from now. Anyone care to arbitrate?
Psychophysiological entity
I have my great grandmother and her mother on glass. It's as good as the day it was made. Modern life however, does not lend itself to caring for these things.
The Texas house is too expencive to cool while we're away for months on end. Everything goes up to at least 90f - and stays around there, night and day.
I had a professional company copy The Making of Bartoli's Vivaldi. Sooooo much better than the CD when I got it. However, after about 2 years max, one of the most beautiful parts was lost. It just couldn't have been a worst place to fail, but fail it did.
It was put onto pro tape, and I'm hoping that's still somewhere in his archives.
The Texas house is too expencive to cool while we're away for months on end. Everything goes up to at least 90f - and stays around there, night and day.
I had a professional company copy The Making of Bartoli's Vivaldi. Sooooo much better than the CD when I got it. However, after about 2 years max, one of the most beautiful parts was lost. It just couldn't have been a worst place to fail, but fail it did.
It was put onto pro tape, and I'm hoping that's still somewhere in his archives.
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The VHS tapes will last longer than the DVDs.
The longevity of DAT (audio) tapes is another bete-noir of mine - and others:
Archivists Warn: Don't Depend on Digital Tape
One snippet from the 1995 article relates to CD-R
The longevity of DAT (audio) tapes is another bete-noir of mine - and others:
Archivists Warn: Don't Depend on Digital Tape
One snippet from the 1995 article relates to CD-R
Nichols, who has started a new company that specializes in audio restoration, said he's been working with Kodak's CD-R, which, through accelerated aging tests, is now said to have an archival life of 267 years.
...Kodak's CD-R, which, through accelerated aging tests, is now said to have an archival life of 267 years.
Now that's impressive.
As BOAC pointed out, brand names can be a trap. It's better to seek out the manufacturer ID. I use the free Nero DiscSpeed
I fell into the trap of buying Kodak branded DVDs. These were actually UME discs, a poor make. 3 of 5 failed.
Some respected makers of optical discs are Taiyo Yuden, Mitsui and Mitsubishi. I have managed to get Taiyo Yuden CDRs, branded as Maxell, in colourful polka dot packs, from WH Smiths. There are other Maxell packs which contain inferior discs.
Further information is here ...also just found this
In the UK, online retailer SVP makes a point of listing the manufacturer ID.
