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Summary: Keeping digital data for a long time, say over 10 or 20 years, presents several unique problems that you'll want to plan on addressing.
Long term archival is a serious issue for two reasons, one that probably won't surprise you, and one that might. There's no single answer, but I can tell you what I do. • Long term archives, archives destined to last, say longer than 10 or 20 years, need special attention, or they're actually likely to fail for one of two reasons:
(There's actually a third problem, software obsolescence. Who's to say that the file formats we save as today will be readable in the future? What if there's no reader for Word documents, AVI video or MP3 audio? This too could happen, but it's not something I'll deal with in this article.) Deterioration has gotten a lot of press in recent years. For example we've heard of old Hollywood movies stored in film canisters falling apart due to chemical reactions, and that archivists are scrambling to save as many of these historical gems as possible. The same applies to any media you might archive your data to. Floppies, CDs, even hard disks will deteriorate over time. The million dollar question is how long will each of those last? And of course there's no specific answer. There are too many variables at play: the quality of the media, the environment that the media is kept in long term, the quality of the device used to create the backups, and so on. "If there's any lesson to be learned about archiving
digital data is that it's not as simple as one might believe."
I actually became concerned at some reports that CDs, for example, start to suffer serious degradation after anywhere from 1 to 5 years. I panicked and started to worry about my older archives, dating back 15 years. I began to copy them to a hard drive and not one failed. All my data was still intact. There are mixed messages about what media types last longest, but my personal rule of thumb is that CDs last longer than floppies, and hard drives last longer than CDs. Each probably by an order of magnitude. But that brings us to the second problem. What do you do when the backup media you used is no longer supported by current hardware? I have had, at various times, 7-track tape (think old 1950's computers in the movies), punched cards, and small tape cartridges as my "archives". I have no way to read or use any of those today. Floppy disks are slowly disappearing. There's a lot of information out there stored on "zip drives" - though I haven't seen a reader for those in years. Will CD's be around forever? That seems unlikely, but the question once again isn't as much if they'll become obsolete, as when. And what they'll be replaced by. A lot can change in 10 or 20 years. So, what do I do? Well, to start with, some time ago when it became clear that floppy disks were heading into history I copied all my backup floppies on to CD-ROMs. Next, I make sure to purchase brand-name media. I'm partial to Memorex and TDK for CDs and DVDs myself, but other name brands, including the ones you mention, should do equally well. There are so called premium "archival" CD media, and I don't really have a good read on whether they're cost effective or not. I still burn backups to CD-ROM (and occasionally DVD, though I still have less faith in the reliability thereof). However, I've also begun a process of copying my oldest CDs to hard disk. Those 15-year old CDs I mentioned? I still have them, but they've also been copied onto an external hard drive, which is itself mirrored to a second drive. My oldest archival CD is now only 8 years old, and over time I plan to catch up and make that more like 5. Yes, I copy to hard drives. My plan is for my "next generation" archival backup to be multi-gigabyte hard drives. These are drives that I've placed in external USB enclosures - here I'm betting that while the internal architecture is slowly changing (from IDE/PATA to SATA) external interfaces such as USB will probably be around longer, at least in a backwards-compatible way. So in 10 or 20 years even though what's inside the USB enclosure might then be considered incredibly ancient technology, there'll still be a USB socket to plug it into somewhere and have it work. (And if it still matters, I can then copy whatever I have to whatever would then be considered appropriate storage.) I think the bets are safer there than on specific media (like CDs or perhaps even DVDs), or internal interfaces such as IDE and SATA. And once again, I'm trying to make sure to get good quality drives for this project. • If there's any lesson to be learned about archiving digital data it's that it's not as simple as one might believe. If you truly plan to keep things for a long time, a plan to migrate digital data from older to newer media and devices (and perhaps even formats) seems the only pragmatic solution. Related:
Article 12183 | Posted January 21, 2008 |
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If you are creating cds or dvd's for archival purposes, purchase archival quality media. They should last a good bit longer than the standard media.
For additional info, see http://adterrasperaspera.com/blog/2006/10/30/how-to-choose-cddvd-archival-media
--Dave
Posted by: Dave Gold at January 25, 2008 07:21 PMI've had a recent problem with a CD that was burnt with a photo archive of mine back in 2003-4. When I went to read, extract something off the disk, guess what, it wouldn't read properly. I managed to use a retrieval program and reclaim about 80% of what was on the disk. I'm not sure if this problem was due to something during the burn process or whether the dye was deteriorating already. Either way, I've now purchased an external HD back-up as well as reburnt a few archive disks.
Posted by: Eugene V at January 25, 2008 08:37 PMMedia are much more vulnerable in tropical climate. Here in Brazil, floppies always tended to fade away within days - sometimes hours.
Posted by: Linde Nobre at January 26, 2008 05:02 AMCDs so far show to be more resistent. But, attention, CD Rom work fine after years, CD RW (rewrite) may deteriorate within a few months. They start to show trails like the ones of termites in wood and do not work anymore.
Harddrives only pose problems where they are constantly hooked to energy: Blackouts may destroy them. Non-hooked-up harddrives may - depending on quality - present fungal problems after a few months.
Depending on the size of the data to be stored, the best long term storage for the average user would be hard disks in terms of speed, size and the cost. I use several 500GB external drives, connected only when necessary, and have a test and re-copy schedule. However, for commercial purposes, I think optical/magneto-optical storage is much better. Reputable online storage companies could be another option and obselescence of the storage method wouldn't be a problem. For portable storage I've been using mini-HD's after I had problems with flash memories and CDRW's. Note that, although the CD/RW's and flash memories are supposed to be re-written hundreds of times, if the quality of the built in hardware programming that is supposed to prevent writing on the same location repeatedly is not good, a single data writing process may require file allocation table to be we-written many times and these areas of the media deteriorate very quickly. So I'd say go with the hard disks, at least for the time being and use other media only for temporary or short time storage.
Posted by: O. A. Orcan at January 28, 2008 12:19 AMwhen I worked in the server room at a certain company I learned to use archival media - gold media. it really depends on how the media is made and the dyes used, etc. as to how long they will last, how much light they will stand up to shelf life, and so on.
Posted by: Jim Michaels at January 28, 2008 01:49 PMGold media is rated for 300 years. silver thermal media is rated for 250, and they are more expensive than regular media. some prepackaged Mitsui MAM-A gold media come diamond-coated to resist scratches.
Hard disks are warrantied for only 5 years, but I have seen then last longer.
there are several outlets that sell Mitsui MAM-A media, one of them is mediasupply.com - they come in several forms, one of them in shrink-wrap (no cakebox). They sell in bulk too. I found decent cakeboxes that lock down nicely at meritline.com
silver thermal is $51/100 and gold is $110/100 I think. but the diamond-coated packaged gold is more expensive than that and it's really heavy and it's bulky of course.
Well, it looks like the old typwriter may make a comeback after all!
http://www.domdedomdom.com/
Posted by: Dominick at January 31, 2008 01:23 PM"In the long run, we are all dead." (Keynes) My long run is shorter than the large majority of computer users, and I often think "why archive data?" rather than "how?".
Yes, I managed to convert my pre-PC data to modern media and file types - but it's rare that I need a file more than a couple of years old. And I can't imagine anyone looking at all those digital photos after God closes my lid.
There's supposed to be an information explosion - let's not make it worse!
Posted by: Eric Deeson at February 8, 2008 08:39 AM