Frequently Asked Questions on Caring for Computer Hard Disks and Diskettes
by Christopher Dicks, Assistant Audio and Video Conservator, Library and Archives Canada, Music Division
Regularly backing up your electronic data is one of the most important habits computer users can develop.
Unfortunately, disaster does strike - hard disks quit working, diskettes become unreadable, files won't open.
In this FAQ, the longevity of various electronic media, how to preserve diskettes and hard disks, retrieve "erased"
files and choose the best formats for long-term storage for your files are explained.
Store your computer diskettes (sometimes called "floppy" disks) in clean storage cases when you are not using
them. There are three major things NOT to do to a diskette:
Do not bend or twist diskettes.
Do not touch the inner surface of the diskettes with your bare hands.
Do not write directly on diskettes or labels placed on diskettes with a hard-tipped pen or pencil.
Cooler and drier storage areas are best. Try to store your diskettes in conditions below 23°C and below 50%
relative humidity. Keep debris and dust away as much as possible.
Back-up diskettes regularly (every two to three years) especially if they are used often.
This can be done by transferring the information to a computer hard disk or to a digital back-up system such as
tape, Zip disks, CD-R, etc. Spot-test your files periodically and transfer the data if readability problems develop.
What is the lifetime of CDs, diskettes, ZIP disks, hard drives, tapes, etc.?
Professionals working intensively with diskettes and hard drives tend to trust them for only
up to five years before they feel a need to copy the data to a new medium or to a new unit of the same medium.
The lifetime ranges of certain media under standard storage conditions (23°C and 50% relative humidity) are:
Read-only CDs (factory stamped): 5 to 100 or more years depending on disc manufacturing quality
CD-Rs (Compact Disc Recordable): 5 to 200 years depending on disc type and manufacturing quality
CD-RWs (Re-Writeable): 5 to 100 or more years depending on manufacturing quality
DVD, DVD-Rs, DVD-RWs (Digital Versatile Disc, Recordable, Re-Writeable): not much data
is available for DVDs, but its lifetime is generally expected to be similar to that of a CD
Tapes: 10 to 30 years
Diskettes and Hard Drive: 5 to 15 years
Storing diskettes in hotter and more humid conditions than recommended will reduce the lifetime ranges stated
above; cooler and drier will extend their life.
The lifetime of the media is one aspect of longevity; the life or popularity of its playback machine is quite another.
The media may survive for 100 years, but the technology to play the media may have disappeared in that time.
Replacement machines might disappear from stores before you have made the change to a new format - for
example, 5.25 inch diskette drives are hard to find nowadays.
If my hard drive won't start up the operating system (such as DOS, Windows or Mac OS)
or if it stops spinning permanently, what can I do?
For most computers, this is the end. Computer hard drives reside in a sealed case (which should never be opened)
inside your computer. If you open the sealed case of the hard disk, you may jeopardize the recovery of your data.
Consult a professional or the manufacturer if problems arise with the hard drive and you need to recover data. Data
recovery can be attempted by companies who charge for this service. The cost per hard drive is between $300 and
$1,000, or sometimes more. You can avoid this costly situation if you back up all your important files on a second
media and if you refresh your data periodically by copying the files to a new medium. Having back-up copies in
the case of hard drive failure is good insurance.
Occasionally viruses can completely disable Windows, Mac, Unix and other operating systems. You may think
that all is lost, but if the drive can be connected to another computer, important files may be accessed long enough
to copy the data. Before attempting this, seek advice from a professional and do a virus scan and virus removal
before copying any files.
Can I prevent my hard drive from burning out, making my computer files inaccessible?
You can extend the life of a drive by keeping the power off on the drive when you do not need to read from
it or by turning off your computer when you are not using it. By storing both the computer and other media
between 21-23°C and between 40-50% relative humidity, you can also keep the drive cooler and safer. A CPU (central
processing unit) fan can cost between $20 and $30. The fan is installed in the computer to keep the hard drive cooler.
Partitioning a drive into separate sections can make file seeking much more efficient for the computer. Partitioning
also reduces wear on the hard drive by reducing the number of spins required to find files.
Use defragmentation software that copies all files and rewrites them so that the parts of each file are consolidated in
one location on the hard drive and not scattered around the drive. This will improve the efficiency of seeking data.
Despite all these preventative measures, never depend on hard drive longevity and always back up your important
files on another medium. Carefully made CD-Rs and additional hard drives are two examples of media to use for
back-up.
Can I retrieve a file that I have erased? Why or why not? What is the key to success?
Possibly. The key to success is to leave your computer on, do no more work, do not open or close programs
until you have attempted to retrieve your file.
When files are "erased", the first character of the file name is changed to a question mark so that it reads
"?ilename". Once a "deleted" file is in this state, the hard disk is permitted by the processor to write new files
in the area occupied by "?ilename". If you execute the "unerase" function provided by Norton Utilities, Windows
and other software programs before storing any new files, you may be able to retrieve your file either partially
or completely.
If you erase a file by mistake, DO NOT surf the Internet for an answer on how to retrieve a deleted file or for
recovery software! An Internet browser program writes temporary files onto your hard disk. Therefore, if your
valued file's name has just been marked as expendable (as described above), then files written to the hard disk
to enable Web browsing will probably be written exactly where you do not want them and your file will be
lost forever.
If my computer or program crashes and I haven't saved the file I was working on, how do I retrieve my file?
The software program you are using might have a setting that automatically saves your file-in-progress periodically
under a pseudonym in a specified location. However, this preventative measure will not help if the setting was not
enabled when you lost the file. Read the Help menu of your software. The back-up file can be located where the
program tells you it should be. Open the back-up file and save it under a new name. This feature only works when
the program closes without you requesting it. You can still try to find an old version of your file, but if you closed
the program on purpose and chose not to save the file, by accident, it is likely gone forever.
In an attempt to avoid the loss of your work, save files every 10 minutes when working on the computer or
whenever you are idle. Make back-up copies when you have finished working on the file. Storing the diskettes,
or other back-up media, in a physically separate location is safer than having two copies in the same location.
If I have created complex files or multimedia files, such as Adobe Acrobat files full of images
and tables and things, how can I be sure to retrieve these types of files in the future?
While a software company may be popular and successful today, no one can guarantee that it will always exist,
or that the file format you use now will always exist. For this reason, save the components of your complex or
multimedia files in their simplest forms and in the simplest file formats that are most likely to endure into the
future. By all means, save your complex files as well.
Ultimately, the simplest file format is a print-out. Use acid-free paper and laser printing, not ink jet (which can
run easily when exposed to water), or use true silver halide photo paper and a photo printer.
Textual information can best be stored in .txt file format. This is ASCII ("asky") - an information exchange
format containing just the characters of the keyboard. ASCII is used by MAC and PC computers, as well as by
self-contained word processor machines, computer software, etc. For example, an Internet page is called an .htm
or .html file, but it is simply a .txt file with a change made to the three or four letter extension on the name so
that Internet browsers can recognize it. So many software programs rely on these simple .txt files for day-to-day
operation that they are unlikely to disappear.
Saving a table is a bit more challenging. As explained, an .htm file is really just a .txt file in disguise. However,
the HTML programming language allows the user to create tables by specifying row, column and cells, along with
bolding, colour and many other types of formatting. In this form, the user could save a table as .txt, but it would
require an Internet browser to render the layout. In fact, the HTML language allows the user to also include
references to pictures and to sound recordings, as long as the proper location of these other files is provided. It
is likely that as the World Wide Web Consortium (W3C) continues to update the standards for Internet documents,
they will continue to require backward compatibility with older .htm files.
Another variation of a table is the CSV (comma separated values) format, which, again, is a .txt file. It is a format
used to export information from a database. In the CSV format, the information following the comma is placed
in the next logical field of a database. A third variation, similar to CSV, is the TSV (tab separated values) format,
which uses tabs instead of commas to separate data. Delimited ASCII format allows combinations of punctuation
or keyboard strokes to be used to assign specific parts of the data to specific fields. Most databases allow the user
to export the software-specific file into a .txt file, which another database software can import and reconstruct the
file within the new software.
Choosing an enduring image format requires using your own judgement. For example, the .bmp format retains
all of the information in an image file, unlike .jpg, which compresses data (throws away information) selectively
to reduce file size. Again, as a means of back up, a colour print could be scanned later to create a new image
if necessary.
Audio files can be saved as .wav files, in which the data is not compressed. Currently, the international broadcast
community is attempting to standardize the BWF (broadcast wave format); therefore, this may be a promising
format for sound recording longevity. However, a BWF file contains metadata (that is, data about the data that
is stored) and is, therefore, not the simplest form you could choose.
If you need professional conservation help, please contact
the Canadian Association of Professional Conservators:
CAPC
c/o Canadian Museums Association
Suite 400, 280 Metcalfe Street
Ottawa ON K2P 1R7
Tel.: (613) 567-0099
Fax: (613) 233-5438 http://www.capc-acrp.ca/index.htm
Additional Resources
For further queries on various areas of conservation, please visit: Canadian Conservation Institute (CCI) Internet site (English and French): http://www.cci-icc.gc.ca/
