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Re: diskette lifespan



Christy Johnson wrote:
> Can anyone please tell me the lifespan of a 3.5" diskette?  If material is
> stored on these disks, how long will they be readable?

This depends.  Major factors are the storage conditions (heat, humidity and fluctuation thereof, any
contaminants in the air, magnetic fields from any nearby equipment), handling and use.  You also have
to consider the variety of quality between different manufacturers and even different production
batches by the same manufacturers.  Some die much faster than others.  The reading hardware is yet
another factor, since a disk that has reached an unacceptable error rate on one reader may still be
readable on another one.

Each medium has a range of potential longevity that will be influenced greatly by the above factors.
The National Media Lab created some really good charts that presented these longevity ranges, but
they're unfortunately no longer "officially" online.  I'm pretty sure there are still some copies of
their charts floating around the Web, though.

If you've got floppies that have been sitting around for as long as 5 years, particularly if the
storage conditions haven't been ideal, you should definitely be concerned.  At the very least, it
would be a good idea to try reading them all periodically.  I would strongly recommend going beyond
this, however, and copying the files to another medium as soon as possible.

Some places you might want to look for some guidance on media longevity:
http://www-personal.si.umich.edu/~calz/ermlinks/pres_med.htm
http://www-personal.si.umich.edu/~calz/ermlinks/store.htm

There's also a mailing list called AV Media Matters that often has quite well-informed discussions
about the longevity of various media.

http://www.topica.com/lists/av-media-matters/

You won't find a lot of treatment in these sources specific to floppy disks, but that's probably
because very few probably consider it to be a viable storage medium for anything more that quick and
dirty copying - "sneaker net" file sharing in an office that's not networked, taking a few files home,
or bringing some presentation files to use on someone else's laptop at a conference.

> Are other forms of electronic storage better?

There are many current storage media that are better than floppy disks.  These include optical media
(e.g. CD, DVD) and magnetic media such as tapes and hard drives.  There are also magneto-optical
media, but they're much less common.

I would recommend getting data off of all floppy formats, even the 3.5" variety.  Not only are floppy
drives becoming less common, but they also contain very little data per disk and are thus a nightmare
to manage and keep track of.  It's hard to keep metadata related to files on floppies, and many
current formats are so bulky that one can't even fit a single file on a floppy, requiring frightening
practices such as zipping files across multiple disks.  Floppies also easy to mishandle and damage.
They tend to get hidden away on dusty shelves and inside folders, only to haunt some poor archivist
who finds them years later.

In many cases, you may find that a reasonable approach is simply to copy all the files you need onto a
hard drive.  Hard drives continue to get more dense and less expensive, and as long as you store two
copies on different disks and/or do backups to an offline medium like tape, you should be safe.  Hard
drives also have very fast read/write times, and they frequently refresh the data, so "bit rot" is
less of an issues than with some other media.  If you have a lot of data that will get read very
rarely and takes up lots of storage space (say, 100s of Gigabytes or more), you may decide instead to
move that data onto a magnetic tape format.  Though even in those cases, you may decide that hard
drives are an attractive option.  The people working on the Internet Archive have decided to move to
hard drives for long-term storage, and they're dealing with terabytes of data.

Many institutions also use CDs for storage, particularly for files that will be written once and then
never or very rarely changed.

Regardless of what medium you choose, having more than one copy (ideally in more than one physical
location) is a good idea.  And there's always the MUCH more difficult issue of making sure that the
software on the media is still compatible with your current computing environment.  The software issue
will tend to be the more expensive one to deal with over time.

=========================================================
 Cal Lee
 University of Michigan
 School of Information
 Phone: 734-647-0505
 http://www-personal.si.umich.edu/~calz/
 "How can I know what I think because I forgot what I said?"
                                         - Karl Weick, 1979

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