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General Information about Media Format Obsolescence

Selecting media for prioritization of preservation activities, such as disk imaging, is a delicate balance of variables. This page outlines three of the major considerations for the initial selection prior to transfer to the BDPL for long-term preservation.

Prioritization Based on Format Risks

Certain formats will remain stable for much longer than others, and can be put off for preservation in order to ensure that other items will be accessible at the time of imaging. Some basic lifetimes for popular media are:

  • CDs/DVDs:  two to twenty years, varies widely based on use and storage conditions
  • Floppy disks: three to twenty years, varies based on storage and brand
  • USBs: 10,000 writes
  • Hard Drives: 3 years, then 12% annual failure rate
  • External Hard Drives: Less time than regular hard drives due to wear and tear

The Museum of Obsolete Media provides Media Stability Ratings for some widely-used obsolete media, which may be of assistance as you assess format risks.

Prioritization Based on Size

Another consideration for selecting born digital obsolete media for preservation involves the size of the original media. A hard drive has much higher capacity and therefore there is more likelihood of it having important files than a floppy disk with a much smaller capacity. Items like servers and computer hard drives should be prioritized immediately for preservation actions.

Prioritization Based on Content and Importance

Probably the most important factor in selection of media for preservation actions is the content and importance to the institution or historic record. The original owner and provenance of the media are very important in determining this, as well as any transcriptions on the label and other items in the collection. 


While there is no right or wrong answer for prioritization of obsolete media for preservation actions, it is important to balance the different variables in a way that will make the stewardship of important institutional and cultural heritage more likely.

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