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Long-term archiving dos and don'ts

Restoring data from long-term archives can be difficult (or impossible) if your archive isn't in a readable format. This tip outlines some ways that you can ensure access to your data over time.

Some legislative requirements mandate that data be kept for as long as 70 years -- that's the easy part. Having to restore a 70-year-old file is the hard part.

Twenty years ago, mainframe backups were done on nine-track, 1-inch tape, while PC backups were likely put on 5.25-inch floppies or audio-cassette tapes. Trying to read any of those media today would be difficult, even assuming the media hadn't deteriorated past readability.

Long-term archiving information
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Best practices for long-term tape archives 

Besides obvious issues like the device and removable media used for archiving, the data format used by the backup program and the format of the data itself, there are additional issues such as the usable lifespan of the media, the necessary keys for any encrypted data and -- a really big one -- the ability to find the name of the data file you want. If that's not enough to discourage you, you may also have to discover where the archive is stored and what specific piece of media actually holds the file.

The following suggestions can help ensure your data will be accessible in the future, and keep you out of hot water:



  • Test the entire process of recovering archived data. Refresh the data format and storage medium.

  • Think about updating data formats to Adobe Systems Inc.'s PDF/A, OpenDoc or some other data format that's likely to be readable in 70 or more years.

  • If your archives need to be encrypted, be sure to plan for recovering old keys even if the encryption software/appliance is no longer in active service.

  • Compare the actual cost of archiving to offline media, managing the data and renewing/refreshing it every five to 10 years against the cost of keeping the data online.



  • Assume you'll be able to read archived data just because the media shelf life is supposed to be longer than the retention period.

  • Assume your storage vendors will still be around in 50 years

  • Throw tapes in a box and hope you won't need them.

This first appeared in Storage magazine's October 2006 issue. Logan G. Harbaugh is a frequent contributer to "Storage" magazine.


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