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Guide to Digital Preservation from NIST
Little Hamster writes "The scientists working on the Digital Preservation Program at the National Institute of Standards and Technology (NIST) has released an excellent 50 page guide on care and handling of CDs and DVDs for long term storage. It talks about the effects of light, moisture, radiation, scratches, marking, adhesive labels, and even playback on the discs. For those slashdotters who is not familiar with the physical made up of these optical discs, there is a very nice chapter explaining all the background. And if you only want to know how to care for your precious data, there is a one page summary. And yes, they agreed that glued-on labels are harmful."
I wonder if post it notes are bad?
Use a black felt pen. If you do it right you get to label the CD and defeat copy protection at the same time
I've had floppies, CDs, DATs, Zip disks and even tapes go corrupt over time.
If it wasnt for multiple backups I'd have been stuffed, so for my personal stuff (and work) I keep everything on the hard disk. Luckily the size doubles every few years, so as long as the size of the data doesnt outgrow the size of the drives, I'll be fine.
It wouldn't hurt to get all your old disks and tapes and (un?) back them up onto a spare hard drive before its too late.
You can't expect to wield supreme executive power, just because some watery tart threw a sword at you
For CDs especially do not:
2. Use a pen,pencil,or fine-tip marker to write on the disc.
When I was young, we didn't have those fancy automatic CD burners, we had to manually write to them. And if you made one error, you had to walk 20 miles through a blizzard to the "local" dealer.
Remember the days that cd roms where kept in caddies which were put into the cdrom reader. According to the guidelines this was a much better solution. Are these caddies and these special cd rom drives still available (new, not second hand) ?. Would be a market for professional users. I use a miltary case, used for storing munition & bombs, for storing my floppies. Since these metal cases are waterproof (and so protect against dust as well) they can enhance the life om my valuable cdroms as well.
If you are looking for a CD storage rack for your music CDs, almost all of them appear to stack the CDs one above the other (i.e. the CDs lie horizontally), which clearly helps to save space. However, now we're told "do not store discs horizontally for a long time (years)" ! So have almost all the CD storage rack manufacturers got it 100% wrong for two decades then?
I'm backing up all of my data onto 8-track tapes and storing them on the dashboard of my car. They will be safe forever there...
I, for one, welcome our new robot overlords
light, moisture, radiation, scratches, marking, adhesive labels
Light can make pretty colours on your walls from the reflection off a CD.
AOL CDs make cool coasters - so moisture is good!
Radiation - anyone try putting a CD in a small bowl of water, putting a paperclip on it and putting it in the microwave?
Scratches - Two words(acronymns): AOL CD
Marking - See Scratching
Adhesive labels - but what other kinds of labels can you get? Surely the adhesive types are preferable to the kind that aren't adhering. I mean if I put a CD in a drive with a label that didn't adhere, I'd ruin the drive alot faster than with an adhesive label.
This was only a test (of my idiocy). Had this been a real example of my idiocy, someone would have killed me by now!
The Library of Congress has a guide right here!
1, 1, 2, 3, 5, 8, 13, 21 -- Mathematics is the Language of Nature.
Knowing how to store data for a long time might not help you much if you can't read it back in 20 years because some twisted DRM scheme stops you.
Boy, I can't wait to use my ??? on my ??? in the future!
Anybody who was able to get the 50 page article know why doing the horizontal bop is bad?
- a double backup is necessary if I want "cold" backup
- burning CDs takes time (for example, I've got 6GB of apps/OS)
- from time to time (2-5 years), a second generation has to be done
- external disks are becoming a bit more affordable (around $1.5/GB, which means less than a dollar for a CD space)
- disks are really fast (seconds instead of minutes for CDs)
I'm currently leaving CDs for backups and "just" using HD backup (from my laptop to my desktop for online backups and from my desktop to an external HD for cold backups). CDs become moving support to bring files to friends (so no long life implied).I've made simple rsync scripts (rsync over ssh for laptop to desktop wireless communication, rsync from disk to disk for desktop). This solution implies good data organization (basically live/shared/cold) but is really fast, simple and up to date.
Are there other
I'm currently planning a bigger (200-500GB) solution based on Firewire drives (I'm using Macs, but it also works on PCs). Do you have any advices/experiences on using those solutions in simple home network?
ClaudeBBG
"Do not: ...
8. Expose recordable discs to prolonged sunlight..."
in other words, make no change in your lifestyle whatsoever.
And if you only want to know how to care for your precious data, there is a one page summary.
They forgot a lot of useful tips. Here they are:
DO:
- not write anything on CDRs. No Data means no data to lose
- use a felt-tip marker to write your data in readable hex format on the label side of multiple CDS, as a backup.
DON'T:
- use your CDs as freesbies to play with the dog
- use your CDs as under-glasses
- punch a hole on the side of the CD to hang it on your key ring
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
I've been shopping for the best brand of CD-RW I can find for longevity, and I'm going to be backing up all my extremely high dpi scans to disk, twice, and storing a set in seperate locations. I sell my original artwork, so this is important to me. I'm glad to know I shouldn't be stacking these vertically. I don't care much about my music CDs since I rarely buy them new or pay more than $5, and keep them in a large binder w/out jewel cases... but my personal data is certainly more important. From now on I will keep my backup data CDs in proper cases and store them as recommended. I'd also like to know which markers are safe to use. I've always used Sharpies in the past.
I also back everything up to the second hard drive in my system, but when dealing with 50-75MB files that can become impractical quickly. I'm paranoid now because I've been through several hard disk failures this year alone.
Does anyone recommend a particular brand of CD-R(W) disks best known for longevity, while on the subject...?
My Webcomic: Asylum on 5th Street
from the 50-page pdf:
Physical mishandling of the disc is usually the cause of polycarbonate*
layer damage. The polycarbonate may also flex or bend if
stored for a long period of time in a nonvertical position.
and
Long-term horizontal storage, particularly in a
heated environment, can cause the disc to become permanently
bowed. While the data may still be intact, the disc may not operate
properly in the drive or permit the laser to follow the track.
*3.1 Polycarbonate (Plastic) Substrate Layer
The polycarbonate substrate makes up most of the disc, including
the area that is read by the laser (opposite the label side on CDs). It
is present on both sides of a DVD, even a "single-sided" disc with a
label on one side. This substrate provides the disc depth necessary
to maintain laser focus on the metal and data layers. It also gives the
disc enough strength to remain flat. Anything in or on the polycarbonate
layer that interferes with the ability of the laser to focus on
the data layer will result in the misreading of data. Accordingly, fingerprints,
smudges, or scratches, as well as such substances as dirt,
dust, solvents, and excessive moisture (which polycarbonate will
absorb), can interfere with the ability of the laser to read the data.
Contact of any foreign material with the polycarbonate substrate
layer should be avoided.
Yes, Sharpies are solvent-based. Look for water-based inks.
Media capacity follows the standard technological growth curve (aka Moore's Law) so that it is both convenient and practical to move your entire library every few years.
Thus my MP3 collection has migrated over time from Jaz cassettes to CDR to large hard disk to DVD.
Apart from the practical aspects of finding a reader for old media, the sheer space taken by old media (e.g. my twenty-odd Jaz cartridges) makes it useful to move regularly.
My MP3 collection, freshly re-created from my original CD collection, fits onto ten data DVDs while it would require about 70 CDRs.
Doing this, while also keeping multiple archives on hard disk (CVS mainly) means I have no problem accessing projects that I worked on 15-20 years ago. No way would I have confidence in diskettes or backup tapes from the same period.
Though I do have a 50cm-wide 150Mb removable Wang disk that has some interesting stuff on it if anyone has an old Wang VS lying around.
Ceci n'est pas une signature
This supposed guide on how to keep CD/DVD discs preserved reminds me of a story back in high school. A friend of mine (around 1997-98) carved his name onto his CD so that other people wouldn't steal it.
Of course, this bright individual decided to carve his name onto the UNDERSIDE of the CD, instead of the top side.
Before I knew this, I asked him if I could borrow the CD so I could rip it to mp3. When I saw the underside of the CD, I realized that there was no help for this person whatsoever.
I think White Zombie plus Acid does bad things to today's youth. Mostly acid.
The most amazing thing is that he graduated high school.
The main lesson here is to TRY and take care of your albums. Don't leave them out, let your kids throw them around the room. But then... this sort of thing is obvious to any doofus who has made it out of high school.
Oh wait...Nevermind.
/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i
Couldn't you counteract the effects of any bowing of the discs by simply flipping them over every year or so?
don't forget to protect against nature's most
destructive force - 3 year old boys on a sugar
buzz.
-- All that's left of me, is slight insanity, whats on the right, I don't know. -- Bob Mould
I'm a little surprised that nothing was mentioned of the CD-eating fungus which has been discussed here a couple of times before. I have personally been the victim of that fungus and lost somewhere in the area of 20 CDs to it.
I live in Southern Mexico where it's hot and humid most of the year, and these conditions apparently make CDs very vulnerable to the fungus. Given that I don't have any environmentally controlled rooms in which to keep my CDs, what should I do? I'm really concerned that my CD-Rs will be ruined from the higher heat which, for most of the year is in the high 80s to high 90s.
I've considered putting my CDs and CD-Rs in the refrigerator, but I'm not sure how safe that is. Can anyone comment on that? My thought was to put them on a spindle and then place that in a ziplock bag, evacuate as much air as possible, and then stick it in the fridge. Can anyone comment on that? I'm afraid even with a little air in the bag, there will be enough condensation to cause a problem. If someone could give me some good advice on how to handle that, I'd really appreciate it.
First paragraph, page 30:
"Numerous CD vendors have noted that the thin protective lacquer coating can deteriorate from contact with certain solvents in markers. To eliminate the risk, water-based markers are recommended for CD labeling. As a solvent, alcohol is generally less damaging than xylene and toluene, which are common in aromatic solvent-based markers. According to anecdotal reports, alcohol-based markers can be used to label CDs without causing performance problems. However, there are no explicit lab test results to show what effect solvents in markers have on different CDs or DVDs, particularly over the long term."
The actually "guide" to care for your DVDs and CDs isn't 50 pages... it's about 2 pages of "do"s and "don't"s. The rest is just technical mumbojumo with the TOC, definition reference, bibliograpy, and other legal stuff at the beginning.
"WOAH 50 PAGES!" Well... yea... but the important stuff is only on a few of them.
So if you plan on printing this out for easy reference... save yourself the extra 48 pages.
You can get free dessicants in a shoe store. There is a small package of silica gel in every box of shoes. Friendly shoe salespeople will be glad to give them to you, since they are normally thrown away.
Putting CDs in a refigerator will work if you put them inside two plastic zipper lock freezer bags, or inside a heavy plastic container. However, use great care when you take them out. Let the entire container warm to room temperature before you open the container. Otherwise the cold plastic will cause moisture condensation.
For those who haven't already seen them, most computer and office supply stores sell markers that are specifically designed for writing on CDs. The last ones I bought were "Smart and Friendly CD Speed Markers", and came in a pack with four different colors.
Sharpies
White-Out
Permanent Markers, unless there happens to be a water-based permanent marker out there. ... But IANACDExpert.
That's a real bummer, considering that I'd rather not put a label on a CD that will later smudge or bleed.
For what it's worth, I've been using Sharpies on my CD-RWs with no apparent problems. The larger article makes it clear that prolonged contact with the solvent is the real issue. So if you write on the CD with a Sharpie and then wave it around for a minute, the solvent will evaporate, leaving the ink behind. So that should be OK
Human being (n.): A genetically human, genetically distinct, functioning organism.
They may contain solvents, but you're probably safe if there is plastic covering the metal burn layer. If the layer is exposed, do not write on it with a solvent based marker. It may react with the solvent and decompose
Here's a previous post on the same thing
http://slashdot.org/comments.pl?sid=85127&
The best preservation for digital media is to not count on the media being reliable in the very-long-term. Instead, you should invest the time and effort into making scheduled, verified copies of the media well before the predicted life of the media.
Of course, you need to not clean your CDs/DVDs with a Brillo pad in between times, and generally take care of them. But for real permanent retention, nothing's better than a fresh copy.
BTW, this copy doesn't even have to be on the same media standard -- sometimes its a good thing to revv that up as well. Remember that British Laserdisc archive they had all that trouble getting the data off of a while back when the players became obsolete?
In answer to your first question; yes it's "real gold" (fake gold, whatever that is, wouldn't have the properties that make gold an appropriate medium for archival purposes).
Of course you're assuming it's a lot of gold, and therefore should cost like gold jewelry. It is a very thin layer, and costs little; it just costs a bit more than a very thin layer of silver or aluminum. You might be getting, say, a dollar's worth (probably much less).
An extra dime or dollar a disk is too much for Wall-Mart's buyers to swallow; you won't see them there.
Resellers whose customers include photographers, research, libraries, content creators, and certain corporate users will stock it.
NIST tells us not to use anything solvent-based, and Sharpies are solvent-based markers. In fact, the Sharpie Materials Safety Data Sheet (pdf) tells us they contain 3 different solvents - a propanol, a butanol, and an alcohol. One Eric Teel of Jefferson public radio (in Oregon) wrote the manufacturer of Sharpies and they said there could be problems.
Damn, and I've got hundreds of CD-Rs written on with Sharpies. I hope they last till I get around to buying a DVD burner and transferring the data.
By far the toughest storage medium I ever encountered was mylar punch tape. That stuff can stand up to anything but fire. I'm a strong strapping lad and I can barely deform even a single strip (and you could still reconstruct the bits from it if you had to). It's decidedly low-density storage by today's standards, but short of carving your bits on rocks or etching them onto gold plates, I don't think you'd find anything better.
This is digital information. Eventually the media is going to fail -- guaranteed. Best approach is to make 100 copies of it at 100 different locations, then make new copies of the copies every year. With massive redundancy so cheap, who cares who unreliably a single copy is? This is one of the as yet untapped possibilities offered by the internet -- to be a perpetual archive for the information people consider important enough to provide the resources to make massively redundant copies.
"Freedom means freedom for everybody" -- Dick Cheney