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Ask Slashdot: Keeping Digital Media After Imaging? 122

Posted by Unknown Lamer
from the digitial-frisbees-for-all dept.
New submitter rogue_archivist writes "I'm an archivist at a mid-sized university archives, trying to develop a policy for archiving computer files ('born-digital records' in archival parlance). Currently old floppy disks, CDs, and the occasional hard drive are added to our network storage. Then the physical media is separated from archival paper documents and placed into storage. My question for all you slashdotters out there is: should these disks be imaged and then the physical copies discarded? Is there any benefit for keeping around physical copies of storage media long since rendered obsolete?"
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Ask Slashdot: Keeping Digital Media After Imaging?

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  • For born-analog content, always keep the original physical copy. You never know when you will need to rescan at a higher quality or when you will discover errors in your digital copy. DVDs are not born analog. In fact the only have a shelf life of around 7 years. You need to get everything off DVDs and make several digital copies of it. You should keep the DVDs as long as possible but eventually you will not be able to read them anymore. Make sure your digital copies of the DVDs are error-free because there
    • by Russ1642 (1087959)

      You're thinking of burned DVDs. Most professional video DVDs are stamped.

    • You never know ... when you will discover errors in your digital copy. DVDs are not born analog. In fact the only have a shelf life of around 7 years. You need to get everything off DVDs and make several digital copies of it. You should keep the DVDs as long as possible but eventually you will not be able to read them anymore. Make sure your digital copies of the DVDs are error-free because there will come a time when you cannot go back to the DVDs.

      Hmm... DVDs only live for 7 years, eh? In an archive?

      I was just watching a DVD last night that I bought in 2000; it still works fine, with no scratches or degradation. I was also pulling data off a DVD-R the other day that I recorded in 2003. This DID have a slight bit of degradation, so maybe there's an issue here. Never had a problem with properly stored pressed DVDs though.

      For that matter, I've still got 5 1/4" floppy disks that have readable data on them from 198, and Audio CDs from 1990. Got rid of

      • by Russ1642 (1087959)

        Well we all know that floppy's from 198 were made of stone so of course they're going to last.

        • by unitron (5733)

          By 198 I think they were already up to parchment and sheepskin, although papyrus hadn't totally fallen out of favor at that point in some parts of the world.

      • The lifespan of a burned DVD is highly unpredictable. Some can last decades - but don't count on it.

      • by ganjadude (952775)
        about 1/2 of my C64 and C128 5 1/4 floppies are still working in the C128 (the 2 64s i have no longer boot, i think a cap popped) the other half are unreadable, at least by the handful of 5 1/4 drives I own. Some of these disks are almost 30 years old. Kept in temp controlled room for the past 13 years (when i aquired them from a school). I cant say ive tested all disks (i have over 500 pounds in weight, just in floppy disks and sleves) but I have to admit that some disks that I know worked in the past are
        • about 1/2 of my C64 and C128 5 1/4 floppies are still working in the C128 (the 2 64s i have no longer boot, i think a cap popped) the other half are unreadable, at least by the handful of 5 1/4 drives I own. Some of these disks are almost 30 years old. Kept in temp controlled room for the past 13 years (when i aquired them from a school). I cant say ive tested all disks (i have over 500 pounds in weight, just in floppy disks and sleves) but I have to admit that some disks that I know worked in the past are not workng as of 6 months ago when I had the urge to set everything back up. But the point im getting at is that there is no way DVDs, DVD-rs or even DVD-rws have a 7 year life.

          I was just watching a DVD last night that I bought in 2000; it still works fine, with no scratches or degradation.

          Commercially pressed DVDs are a different beast than the ones you write yourself. The foil is etched and pressed into the plastic instead of inks being hit by lasers after assembly. The ones you write yourself seem to have about a 7-10 year life if you treat them well.

    • by PRMan (959735) on Tuesday July 23, 2013 @05:48PM (#44365669)
      Not this tired argument again. I have burned CDs from 1995 that still work perfectly fine. Sure, they "estimated" that they would only last 7 years. Guess they were wrong, since unless I can see physical scratches or other damage, 99% of my discs from my life still work perfectly. The only ones that didn't last and had no physical damage were a cheap brand I got where the dye turned cloudy, but that happened within the first 2 years.
      • by cusco (717999)
        Don't leave them laying in the sun. I was able to say the same thing until I left a burned CD from the late '90s on the window sill a couple of years ago. Four of the five CD players that I put it in couldn't read it at all, and the fifth could only make sense of about half of it.
      • by Miamicanes (730264) on Tuesday July 23, 2013 @06:41PM (#44366163)

        > I have burned CDs from 1995 that still work perfectly fine.

        If they're redbook audio CDs, and your definition of "work perfectly fine" is "I can stick the disk in, hit play, it spins up at 1X, music comes out, and the player doesn't totally gag", you might be right. Now try ripping the disc using software that can monitor the realtime bit error rate. You'll probably be *horrified* to see how high it is.

        Redbook audio CDs are very robust, even when their bits are rotting all over the place. They were designed in an era when hardware couldn't do much in realtime, so they bent over backwards to make sure they had a "plan B" to make sure the show would go on after the disc got scratched, dirty, or whatever else happened to it. They were designed so the audio data is interleaved in a way that when a read error occurs, the left and right channels get merged for 1 sample. A redbook audio CD has to be nearly *destroyed* (cracked, melted, fried, whatever) before it literally won't play, as long as the player is able to find the lead-in and sync up to the spiral track.

        It'll start to sound "rough" and lose channel separation, but things have to be pretty bad before it will LITERALLY stop playing. At least, as long as the player itself is faithfully following the original redbook audio specs, and isn't trying to realtime-rip the audio to a ram buffer and play it back from there (which is what some, if not most, new optical-disc media players do TODAY). I have plenty of CDs that new players choke on and refuse to even try playing, but yet my 25 year old antique CD player that cost something outrageous like $600 or $800 when new, can play just fine. Apparently, it's because first-generation CD players were precision hardware that could blindly track a CD spiral as long as the disc itself was 100% within spec, whereas new players depend upon realtime error-analysis to stumble and wobble around, and make up for the fact that discs no longer spin precisely, and worm-gear optical assemblies no longer track with precision measured in microns.

        That said, my experience has ALSO been that CD-R discs manufactured in THIS century are less likely to rot and become unplayable in new drives, but are more likely to have major problems with old players. The old players were precision hardware, and assumed the discs themselves were manufactured to precision specs. The first-gen CD-R media had dye that deteriorated over time, but their spiral tracks were spot-on, just like pressed discs. As drives got better at handling sloppy tracking, the discs themselves became sloppier.

        Net effect: first-gen redbook audio CD-R media is likely to play with acceptable audio quality on an old CD player from the 80s or early 90s, but be unplayable on many modern drives & be un-rippable on most drives (some will allow you to spin down to 1X & emulate the playback mode of a legacy player if you're running a sophisticated ripping app). Newer discs that are still old will probably skip and have problems playing on an old player, but might still be equally bad on a new one. When today's bargain-bin CD-R media is 10 years old, it will probably be unplayable on anything, the same way my old VHS tapes from the 80s still play fine, but VHS tapes recorded after ~1998 are largely unplayable on anything I can find.

        TLDR point: the storage life of "last-gen" CD-R media is likely to be better than first-gen CD-R media was at the same age, but enormously WORSE than that of the best "turn of the century" CD-R media (the golden era when quality standards were still high, and the worst faults of the first-gen media were addressed. Any box of CD-R media you buy TODAY is probably shit of the worst kind. The best media you can buy TODAY for long storage life? Non-LTH BD-R single-layer discs. But MAKE SURE they aren't LTH... most manufacturers don't go out of their way to scream, "These discs are LTH garbage!"

        • by robogun (466062)

          Never gave a second thought to storage of CDs. I have a very old CD collection - many discs from the 1980s. After reading this, I ran in a panic to see if they still play. Hmmm. they all still play and are rippable. I am a photographer. Have backed up images onto several standard file boxes of CDRs, from 1999-2003, then copied to DVDRs (just filling the first standard file box), then large HDs. They are jammed in sleeves, not jewel cases. Random samples all play. It is the hard drive backups that are miser

          • Another big problem that bites lots of people with CD-R specifically... CD-ROM/XA Mode 2, Form 2... and the willingness -- if not eager default -- of early software like Nero to allow users to disable error correction to gain a few more megs of storage space without making it abundantly clear to those same users what the consequences of doing it were. Lots of people went for YEARS burning discs that would develop hard errors at the slightest scratch without realizing WHY it was happening. They just attribut

    • by vux984 (928602)

      You should keep the DVDs as long as possible

      Bottom line, if you have N digital copies then what is the benefit of keeping the original DVD over one N+1 digital copies of the DVD?

      Near as I can tell. Zero benefit. And massively increased storage requirements. So make one extra digital archive and discard them. Better still donate them! to public libraries? independent / private archivists? You don't have to "destroy" them -- which is surely about as counter-instinctual as it gets for an archivist. :)

      eventua

      • by vux984 (928602)

        er... "2 different rips of the same disc"

        I actually meant rips of the same title from different discs.

      • > Bottom line, if you have N digital copies then what is the benefit of keeping the original DVD over one N+1 digital copies of the DVD?

        The original DVD was pressed. Digital copies depend upon either brittle spinning hard drives that are cost-prohibitive to repair and recover data from, flash media that's the equivalent of a leaky bucket (especially MLC), organic-dye based optical media that shift over time, and manufacturing processes whose lifetimes are absolutely 100% speculation to begin with.

        The mor

    • > For born-analog content, always keep the original physical copy.

      And if, for whatever reason, you CAN'T retain the original copy, oversample the bejesus out of it, store it with the most lossless compression you can, and sample it multiple times, in multiple ways, with multiple scanners/digitizers/capture cards.

      Case in point: videotape. If your goal is to merely capture a copy to casually watch years later, and you don't mind having a digital copy that's demonstrably worse than the analog original, just

  • by innocent_white_lamb (151825) on Tuesday July 23, 2013 @04:54PM (#44365131)

    Your interest is in the contents, not the container. Therefore, once you have a known-good copy of the data, you're all set.

    Remember to keep a few of the old tapes/drives/whatever for the museum display, of course.

    • Your interest is in the contents, not the container. Therefore, once you have a known-good copy of the data, you're all set.

      Remember to keep a few of the old tapes/drives/whatever for the museum display, of course.

      You might be interested in the "container" if it was itself interesting for some reason. A floppy disk owned by a particular person and labelled in their hand comes to mind as an example. Maybe something was crammed in the disk envelope with the disk. If it's of interest, you'd probably want to keep this piece of ephemera with the original item that contained it if it's safe to both items to do so.

      OTOH . . . I would think that this would be avery unusual case.

      • by Genda (560240)

        Indeed... an original floppy disk with a note penned by the hand of Galileo himself, might have real historical value ;-)

        • by rk (6314)

          Nah, I have lots of those. Would you be interested in some? $9.99 each, but I'm running a special: 3 for $20!

      • by skids (119237)

        Other things to consider are whether, on rewriteable media, the media may contain shadows of deleted data that may be of historical interest, and even on write-once media, whether the software you are using to copy it is copying everything it can, if there might be, e.g. stenography in a redbook CD Q channel.

        I expect such concerns would only be relevent to certain special cases.

      • by RealGene (1025017)
        I have several CD-ROMs and floppies where the software's installation key is either printed on the media label, or on another label affixed to the jewel case.
        I could have a pristine digital copy of the contents, and still not be able to access it...
    • by doti (966971)

      once you have a known-good copy of the data AND made a backup of that.

      ALWAYS have at least two separated copies, peferably more.

    • by westlake (615356)

      Your interest is in the contents, not the container. Therefore, once you have a known-good copy of the data, you're all set.

      assuming nothing happens to the new container.

      and assuming the new container can store all the data recoverable now or in the future from a primary source.

      the "known good" copy from the geek's point of view may not mean the same thing as having everything you need to authenticate the record in a court of law.

  • by Sparticus789 (2625955) on Tuesday July 23, 2013 @04:55PM (#44365137) Journal

    I work on a team which does archiving. We have multiple layers of data storage. First, we keep all copies of media in a library. The media is imaged and stored on a SAN. The SAN is backed up to an off-site NAS. And once a year, we copy the data to hard drives and ship the drives to another site across the country. If you have the capability, put the originals in an archival storage area. I have never known a single archivist to get rid of anything, so you must be new to this community.

    As an FYI, there is no such thing as obsolete media, as evidence by this project [loc.gov]. And trust me, you can usually find a way to image most old media formats.

    • You make a good point about no medium being truly obsolete. As long as there's enough funding, that is. Also, archivists get rid of things all the time through deaccessioning or weeding, and with physical storage space always being at a premium, it prompted my question.
    • Just remember that imaging the bits is only half the equation -- you're also going to want to document the file format unless you really want someone to have to reverse engineer those .abx documents from 1985 from scratch every time they want to make sense of the contents.

    • by Spazmania (174582)

      Floppy disks go bad pretty quickly. Few of yours disks from 1993 still work. Tough to find any working disks from 1983. Unless there's something inherent to the disk itself (the "original" software with the artwork and sleeve) there's not a whole lot of point in keeping it after securing the data.

      And God help you with tapes.

      Hard disks have better longevity. If you can find a working PC-AT with a working MFM controller you can probably still boot that 40 meg drive from 1988. But... why? You can fit thousands

      • You are just completely wrong. I have boxes and boxes full of software from pre-1993 that is readable and that I am able to collect data off of. Just the other day, I booted an Apple SE and read 20 different 3.5 inch floppy disks.

  • Old media will become obsolete and degrade ofer time. It is best to copy to modern media. The files should be stored based on their SHA hash code, so that duplicates need not be stored. You can't have too many copies.
    • by mlts (1038732) *

      What would be ideal is a file format that stores data with some error correction, so if a block got corrupted on older media, the corruption wouldn't just be detectable, but possibly correctable.

      It isn't really "archival grade", but I've used the WinRAR utility for this. Archives made in 1999-2000 with error correction are still readable, check-able, and repairable, and can be moved from old CD-R to DVD to Blu-Ray, possibly to whatever the next generation of optical media will be. In fact, multi-volume ar

      • PAR2 files.

        That's exactly what you need. I used to stick 200MB of par2 data onto every DVD-R I burned - if a file was found damaged years later, that was almost always enough to recover the lost blocks.

        • PAR2 files.

          That will help if it's merely a bit of file contents which were lost, but what do you do if the error is in the filesystem metadata? You need to be able to access the filesystem to read the PAR2 files, along with the rest of the disc's content. If you lose an inode or superblock then a PAR2 file would be out of reach, even if you can recover the remaining blocks from the disk image.

          Is there a way to add PAR2 data to a raw disc image while still allowing the disc to be read with standard tools?

          • There's no need to keep the PAR2 files on the same media, but even if they are you can identify them by their magic bytes and recover them even if the filesystem is unuseable, so long as they are not fragmented. And once that's done, you can in turn use the par2 files list of slice hashes to conduct a brute-force search of the raw device for matching data. I wrote a program to do just that, many years ago.

    • Do we have a digital archival container format? I.e. a tar archive with built-in error correction to identify missing bits, lets say with a SHA hash, and a method to recompute the lost bits, lets say with an XOR operation? Do we have anything like that?

      If you have a good checksum hash and known file size, but the data is corrupted, you could semi-randomly replace bits in a brute force fashion until you produced anther file with the same hash. The possiblity of reconstructing the bits in an alternate fashio

  • OK, keep in mind that I'm being rather abstract here:

    What makes a thing obsolete? That it isn't a commonly used item anymore, or that its usefulness has become non-existent?

    Take, for example, the carrier pigeon - once considered 'obsolete' due to the invention of telecommunications equipment, I can see the medium coming back into vogue in wake of the new knowledge that governments the world over are monitoring our every word over the aforementioned modern channels. Today, you can't send a message along elec

  • by gl4ss (559668) on Tuesday July 23, 2013 @05:03PM (#44365201) Homepage Journal

    ..or can check all of the content to be perfectly read, then yeah, sure, no loss in destroying the originals.

    however.. if you have the space, why destroy? another issue is sw where you in theory might have to prove ownership of a legit copy or the originals might have some other curiosity value. another thing with paper records is that if you destroy the old ones, what was stopping you from introducing new data like a record for your uncles graduation from said university and with you having destroyed the paper records no way to go check them.

    so my question is, is it really that expensive to store them, just for posterity's sake? even then you could just destroy them via sloppy storage rather than intentionally burning energy for destroying them..

    • by TubeSteak (669689)

      so my question is, is it really that expensive to store them, just for posterity's sake? even then you could just destroy them via sloppy storage rather than intentionally burning energy for destroying them..

      There's no practical difference between an item you can't find and an item that's been destroyed.

      So in reality, you don't even have to destroy the stored items, just go ahead and lose the manifest.

  • Unless you are paying Manhattan real estate prices, why not keep the originals? They serve as another backup. They will likely not be too much of a burden. Most "obsolete" media is still perfectly usable and may be so for quite some time.

    There is simply no need to rush into destroying something you already have and can serve as an alternate form of backup.

    Originals always have some value in being the definitive version of something.

  • It's always interesting to see the files and what they were kept on. Floppy disks, whether 3, 5 or 9in variety. Old tape reels, large disk platters... "This file took up 3 of these..." or..

    An entire windowing system (macos) PLUS MS-Word fit on two floppy disks.

    My phone currently has more storage than the enterprise datacenter that I used to work at in the 80s. And it was a LARGE datacenter...

  • by TechyImmigrant (175943) on Tuesday July 23, 2013 @05:10PM (#44365281) Journal

    If you had a 1979 copy of Wizardry on an Apple ][ floppy disk, you could images the contents. But if you wrote them back to a disk and tried to run it, it would fail.

    This is because as a means of copy protection, Wizardry used track arcing. Part of a track was written on a track. Another partial track was written half a head-step away. The timing of the writes was synchronized so the partial tracks didn't overwrite. Anyone doing a naive read and write, or even a not-so-naive scan of the half tracks would fail, because they would get the timing of the writes necessary to prevent collision and to meet the consistency checks in the program.

    Obviously people reverse engineered this and wrote adaptive copy programs that you could direct to do the right thing, but how is an archivist going to know that?

    If you can get this level of deviousness on a primitive floppy disk, I imagine that there is plenty of deviousness to go around on other formats.

    Keep the media.

    • That kind of creative copy-protection is infamous, but for largely institutional or personal records, most people wouldn't have gone to that level of trouble just to obfuscate data. If they had, then we may miss out on some hidden data, but I don't think that argument alone can justify keeping around any type of storage medium that may have a timing trick, hidden filesystem, or other form of protection. At the same time, folks have developed functional technology [kryoflux.com] to record timing information as well as bi
    • I have no mod points at the moment. But that's a VERY important point: A straight copy may not be good enough, due to outside-the-standards copy protection schemes.

      Other floppy-based commercial games used a number of other techniques.

      (One, for instance, had track 3 deliberately corrupted, by scratching the medium with a pin. No error on reading it - or writing and re-reading it - and the game would load, erase the disk, and play. This let the person who made the copy think he had a good copy - when in f

      • by tlhIngan (30335)

        You get the same thing on other media as well - even analog. (Example: Macrovision, which plays with the sync and saturation levels, so that analog TVs intended for over-the-air reception (usually) correct the distortion as if it were a fading signal, while videotape machines copy the "fading" picture and regenerate a non-fading sync, so the copy isn't corrected when viewed.)

        Actually, Macrovision played havoc with the sync pulses - it would produce a deliberately too weak one (but enough that most VCRs coul

    • by tibit (1762298)

      Other formats are usually readable by a device with fairly closed firmware that is designed to spec. Nobody gives you a CD-ROM drive with access to head positioning servo loop and access to the raw bitstream after clock recovery. Yet this is almost what you has on Apple ][ - that's why the floppy controller hardware was so simple (a couple stock TTL chips, maybe a PAL or two). The magic was in the software (firmware). Same goes for a modern CD-ROM drive, but the firmware is not really easily amenable to hac

  • by Anonymous Coward

    I implemented that archive system and I got great support, knowledge and experiance from their community : https://wiki.duraspace.org/display/DSPACE/Discussion

  • by Anonymous Coward

    Get rid of the darn things. Make sure you have the proper emulation and other tools you need, be sure to reformat, but absolutely get rid of the disks. They will fail (magnetic impulses cannot be captured forever) and you will be left with a goodly-sized stock of unreadable media (in fact, IIRC, latest NDSA suggestions are to remove all files from optical media ASAP). Save yourself the trouble and the expense and dump them from the start.

  • I don't know what your goals and requirements are, but I wouldn't bet on old floppies, CDs, or even hard drives lasting for very long. There's an essential problem with old physical media in that the readers are becoming more scarce. You may have a lot of floppies, but how easy is it to find a floppy drive? It's not always easy to find adapters for old IDE or SCSI formats as newer interfaces have been developed. Personally, I don't expect CD/DVD drives to be around in 10 years.

    But beyond that, there's

    • by PRMan (959735)
      I have never had a CD "go bad" except for one cheap batch I got where the dye turned cloudy within a year. Every other CD-R in my possession still reads perfectly unless it is obviously damaged.
      • Well I'm not sure what to tell you. You've been lucky...?

        I've seen plenty go bad. From what I've read on the subject, it supposedly depends on the quality of the manufacture, and the chemicals used in the dye. Though CDs can theoretically last something like a few hundred years, much of what's being sold isn't expected to last more than a few years. Again, that's from what I've read. I know for a fact that I've seen many of my own CDs and DVDs go bad without any physical damage.

    • by jedidiah (1196)

      Then save your appetite for destruction for when the original media is genuinely unreadable. There is no need to hasten that which is only perceived as inevitable.

      Trash it once it actually is trash.

      Don't bother until then.

      I've stored CDs in pretty harsh ways and managed to get far more than 6 years of shelf life out of them. They aren't nearly that fragile. Some are subject to manufacturing defects but that's another sort of problem and it's hardly universal.

      • by hedwards (940851)

        I disagree, keeping the original only makes sense when the original is in a stable format and you have plenty of room.

        I've been dealing with this problem on a much smaller scale, and if you aren't extremely careful it can be hard to keep track of which disks you're keeping because you can, and which ones you're keeping because you have to.

        Dump it to disk, verify the contents, back it up and chuck the original media. In the long term, 1 CDROM is going to last better than 400 or so floppies will.

        Now, if you'r

      • Then save your appetite for destruction for when the original media is genuinely unreadable. There is no need to hasten that which is only perceived as inevitable.

        I can think of some reasons to "hasten that which is... inevitable." First, there's the issue of clutter. There's no need to keep 1000 floppies when the data can all be stored on a single hard drive. If there's sensitive/confidential information on the floppies, having lots of disks is harder to keep track of and therefore potentially less secure. It's technically possible for accessing data on unreliable media to lead to some form of silent data corruption. Perhaps as important as anything else, havin

  • I was recently did the same thing. I had about 2 old OnStream 30 GiG tapes and a hand full of old QIC-80's. Not even mention the CD-R pile in my room.

    During the years I never had the space to just extract everything and sort though it all. Not to mention I would move backup data from tape, to CD, back to tape so I have copy's of the same things all over the spectrum. I have recently started consolidating it all, finding an old OnStream tape drive and old QIC floppy drives to restore everything to a si

    • He thinks in 10 years he'll have a Hoarder's Crisis.
    • by hedwards (940851)

      I'm in a similar situation, just not to that extent. One of the tricks is to categorize things and decide roughly where things belong before you start. Then move things to the correct place, verify the copy and back up. After that, I generally destroy the original, especially if it's in a weird format. (And yes, I consider 3.5" floppies to be a weird format, and really anything other than CDROM or DVDROM at this point)

  • the app store ideas and apples lack of ports is bad for archiving.

    We may get to the point where the app store sand boxing makes it so that an archiving app can't put the files in an place where other apps can see it. and we may have hard time reading an outside data source as well.

  • Though it is not my primary business, I offer my services when people have difficulties accessing archives. I am often surprised when people come to me to rescue data off floppies, both 3 1/2 and 5 1/4. These are mostly legal documents or contracts. Why people keep floppies but not drives to read them is beyond me. I have a 3 1/2 USB drive I keep for routine work. I saved a Pentium 90 with a 5 1/4 inch at home I use for those rare occasions. The other problem is reading the data. I have Office 97 on the Pen
    • by tibit (1762298)

      Wordstar is pretty much a text file. All you need to do is mask out the upper bit. You'll have some control characters left, but those are easy to remove. That's what I remember from 2.5 decades ago...

  • The Basics (Score:5, Informative)

    by westlake (615356) on Tuesday July 23, 2013 @07:35PM (#44366539)

    I'm an archivist at a mid-sized university archives, trying to develop a policy for archiving computer files ('born-digital records' in archival parlance).

    Get Your Bits Off (Old Storage Media) [loc.gov]

    Demystifying Born Digital Reports [oclc.org]

    Working Draft of the Levels of Digital Preservation Chart [loc.gov]

  • The actuality of bit-rot in media is uncertain. Many documents 500 years old are readable-ish if you have the skills and accept that some parts may have decayed. That tells us a lot about te exact media people used way back then.

    The trouble with digital records is this:-
    Searchability is a requirement (even though we don't expect that with written records). The reason is that there is so much of it when compared with the sparse records of times past. So you need a 'good' copy for data analysis and so

  • DVDs, even commercially stamped, can suffer from bit rot. Optical disk technology is inherently flaky. Use multiple HD backups and make sure you have offsite storage.
  • by Tim99 (984437) on Tuesday July 23, 2013 @08:43PM (#44366919)
    One problem about a purely digital archive copy of an original media item is that the information that has been physically written onto the item (handwriting, or a printed label, or artwork on a DVD etc) may not be archived. In some cases this information has little value - On the other hand, it may have great historical significance, like a handwritten note on a DVD by someone who is later awarded a Nobel Prize. You as an archivist do not necessarily know what will be important, and you cannot retrieve this after the item has been destroyed.

    A compromise that may be acceptable is that you digitise photo-images of the appearance of the item and ensure that this information always remains associated with the digitised content.
    • This. I logged in to say this.

      An archivist should keep the original as much as possible. Otherwise, what's the point? Would it be acceptable to photocopy a letter and than discard the original because it's too old? No. You photocopy (or actually non-destructively scan these days), and then you keep the original in a climate controlled environment. People can work off the copy, but sooner or later someone will want to look at the original.

      At a minimum you take high-resolution photos of the media and record t

  • As a photographer myself I would recommend to print out the best choice prints and store them physically, as photographic prints still has the best record for preservation when compared to any / all types of digital media. By all means take running copies of all your data, on and offsite backup. A physical copy of the best prints though is likely to be preserved longer.

  • by pprboy (203649)

    3 is 2
    2 is 1
    1 is none.
    best way to make sure you have it
    3 copies
    2 different media, at least (hd, ssd, thumb, cd, dvd, tape, cloud)
    1 is offsite.

A penny saved is a penny to squander. -- Ambrose Bierce

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