Future Proofing Computer Data

Future proof file formats are important. Historians, genealogists, archaeologists, anthropologists, biographers, repair technicians, librarians, people who restore old equipment, and many others depend on reading old files/documents much further into the future than one might expect. Even a document that seems as inconsequential as a personal letter may be needed a century later; much of the information in our history books actually was gleaned from personal letters. Old paper information survived. Badly designed electronic formats will not survive even if the bits are preserved or resurected by future technologies that can read dead media. Non-consumer equipment often has a lifetime of 20 or 30 years. People restore 100 year old radios. In case of apocolyptic events, the designs of today could be needed for a very long time. Indeed, older designs might be more useful than more recent ones because they use semiconductors that don't fail after a few years due to diffusion. Being able to convert old files can be important for legal reasons. Patents can last something like 75 years. The patent office can issue patents for techniques that have been used for decades. 30 year old computers are still being used by collectors and museums. Old technology is sometimes shippped to third world countries where it is kept alive long after it is considered obsolete in industrial countries. The best speaker design today was developed in the 1945. That is 60 years old. If Paul Klipsh had used a CAD system to design those speakers, would we be able to read the files today? The company still hand builds klipschorns to order even though there are not enough people with the money and discriminating taste to permit mass production. I have laboratory equipment that is 30 years old. Expensive medical imaging eqipment (MRI, Cat scan, etc.) leads 4 lives just in the US: paying humans, paying animals, pro bono humans, pro bono animals. How old will that equipment be by the time it is crated up and shipped to the poorest country on earth? The text can be recovered from a 25 year old wordstar document in seconds by stripping off the high bit and it would take a programmer only a few hours to write a utility to recover the original formating but a ten year old Microsoft Word document is essentially unreadable today. Even todays Word files are only readable by Microsoft Word and a few other programs, none of which are suitable for many purposes. A clean HTML document that doesn't rely on attrocities such as javascript, java, and activeX will be readable 100 years from now.

Some Bad formats

• Microsoft Anything: Word, Excell, Powerpoint, etc.
• Word Perfect, Quatro Pro, etc.
• .DWG (2D CADD)
• Most binary formats (exception is image files which need to use binary format)
• Binary DBMS formats
• Shockwave Flash
• PDF
• All undocumented formats

Some Good formats:

• XML
• Docbook
• TEI-Lite
• HTML
• OpenOffice.org word processor, spreadsheet, presentations, etc. (.zip compressed
• DXF (2D CADD)
• Postscript (not great, but better than PDF)
• A few key well documented and widely used binary formats such as PNG, JPEG.

Store a copy of the file format documentation on the same media as the files. Store files uncompressed if possible. If you must use compression, use a well documented compression format with open source utilities. Store the source code for the utility program and the documentation for the compression format on the same media as the data files. A single error in a compressed file can render the entire remainder of the file unreadable while only the unreadable portions of a compressed file are lost.

Periodically copy your old media to protect against bit rot and to store it on more current media formats. It also lets you know which files have been damaged by bit rot so you have a chance to recover the data from other sources before those sources cease to exist. 7 track tape drives and 8 inch floppy drives are almost non-existent, 5-1/4 floppy drives are rare, 9 track tape drives are rarer still, and many new machines now ship without a 3-1/2" floppy drive. Drives that can read onlder tape cartridges are rare. CD-R and DVD+/-R should be readable for quite a while. Store important documents on multiple disks, preferably in different locations and protected from heat, light, and humidity.