Computer hard disks and diskettes – FAQ
by Christopher Dicks, former Assistant Audio and Video Conservator, Library and Archives Canada, Music Division, and edited by Joe Iraci, Senior Conservation Scientist, Canadian Conservation Institute.
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 and files will not open.
This FAQ explains the longevity of various electronic media, how to preserve diskettes and hard disks, the retrieval of "erased" files and choosing the best formats for the long-term storage of your files.
Table of Contents
How do I preserve computer diskettes?
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:
- bend or twist diskettes
- touch the inner surface of the diskettes with your bare hands
- 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% RH. Keep debris and dust away as much as possible.
Computer diskettes and drives to read them are becoming rare as time goes on. Most new computers do not come with floppy diskette drives. It is recommended to transfer files from floppy diskettes to a more current medium, such as optical discs or a computer hard drive, to ensure the readability of the files into the future.
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% RH) are:
- Read-only CDs (factory stamped): 50 to 100 years
- CD-Rs: 5 to over 100 years, depending on dye and metal layer type
- CD-RWs: 20 to 50 years
- Read-only DVDs (factory stamped): 10 to 20 years
- DVD-Rs: 10 to 50 years
- DVD-RWs: 5 to 20 years
- Analog Tapes: 10 to 30 years
- Digital Tapes: 5 to 10 years
- Floppy Diskettes (including ZIP Disks): 5 to 15 years
- Hard Drives: 2 to 5 years
Storing media in hotter and more humid conditions than recommended will reduce the lifetime ranges stated above; cooler and drier conditions 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. Always monitor technology trends and transfer information off of old formats and on to more current formats before it is too late.
If my hard drive will not start up the operating system (such as Windows or Mac OS) or if it stops spinning permanently, what can I do?
For most computers, this is the end. Computer hard disks reside in a sealed case (which should never be opened). The sealed case resides either inside or outside of your computer. If it is outside, it is connected to the computer via a USB connection. 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 minimum, but can often be more. You can avoid this costly situation if you back up all of your important files on a second medium and if you periodically copy the files to a new medium when deterioration is becoming evident or the technology begins to become obsolete. Having back-up copies in the case of hard drive failure is good insurance. Storing back-up media in a physically separate location is safer than having two copies in the same location.
Occasionally, viruses can completely disable Windows, Mac 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 possibly extend the life of a hard drive by putting it in sleep mode 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% RH, you can also keep the drive cooler and safer. A CPU fan can cost between $20 and $30. The fan is installed in the computer to keep the hard drive cooler. Avoid exposing the hard drive to large and sudden fluctuations in environmental conditions. Avoid bumping and jarring the hard drive, especially when it is in use. It is a good idea to connect the computer to an uninterruptable power supply to protect against electrical surges and sudden shutdown of the computer.
Partitioning a hard drive into separate sections can make file seeking more efficient by reducing the number of spins required to find files and therefore also reducing the wear and tear on the drive since it is not working as hard.
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 and reduce wear on the hard drive components.
Despite all these preventative measures, never depend on a hard drive for longevity and always back up your important files on another medium. Carefully made CD-Rs or DVD-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, and to 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 have not 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, by accident, chose not to save the file, 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.
If I have created complex files or multimedia files, such as Adobe Acrobat files full of images and tables and other elements, 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 silver halide photo paper or other photo printing paper with high stability and a photo printer.
Textual information can best be stored in the .txt file format. This is ASCII – 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 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 theTSV 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 within the new software.
Choosing an enduring image format requires using your own judgement. For example, the .tiff 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; 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.
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