Non-current Portable Optical Media

   Critically Endangered small

Materials saved to DVDs, CDs or other optical storage devices where the media is out of warranty and reader devices may no longer be supported or integrated easily into hardware infrastructure: typically, more than five years old.

Digital Species: Portable Media

Trend in 2022:

No change No Change

Consensus Decision

Added to List: 2019

Trend in 2023:

No change No Change

Previously: Critically Endangered

Imminence of Action

Action is recommended within three years, detailed assessment within one year.

Significance of Loss

The loss of tools, data or services within this group would impact on people and sectors around the world.

Effort to Preserve | Inevitability

It would require a major effort to prevent or reduce losses in this group, possibly requiring the development of new preservation tools or techniques.


CDs, laserdisc technologies, DVD, HDVD

‘Practically Extinct’ in the Presence of Aggravating Conditions

Poor storage; inability to access readers; no replication; encryption.

‘Endangered’ in the Presence of Good Practice

Active management; dependable access to readers; strong documentation; documentation independent from the media.

2023 Review

This entry was added in 2019 to ensure that the range of media storage is properly assessed and presented. Optical media is in some senses a preferred option as it is typically more stable than magnetic or solid state media: but these characteristics have been oversold. The substrates of the disks can prove unstable, and more importantly, the reader technology tends to be proprietary and can become obsolete long before the disks degrade. Storage at scale also means the percentage likelihood of failure increases. The 2021 Jury agreed with the entry’s assigned risk classification with no noted changes towards increased or reduced risk.

The 2023 Council agreed with the risk classification of Critically Endangered with the overall risks remaining on the same basis as before (no change to the trend).

Additional Comments

We know what to do; it is the scale of the problem. It is a big scale problem - and in many library catalogues the information about these carriers and their playing requirements do not exist in metadata. Big scale surveys of collections to identify these carriers might be a barrier to starting to tackle this one.

Optical media is less and less recoverable as time goes on. The data cannot be actively managed, the readers are starting to go out of style, and the carriers will continue to rapidly degrade. Early generations of this media are not as robust as the current generation and can deteriorate significantly if not stored appropriately. Many optical media that were created by individuals using consumer-grade hardware and software are more vulnerable than media created using commercial-grade production techniques, and often user error makes the data unreadable before bitrot and other degradation is able to begin. The presence of adhesive labels can be a big warning sign of this type of vulnerability.

Case Studies or Examples:

  • The British Library's Flashback project, a proof-of-concept that explored the practical challenges of preserving digital content stored on physical media (magnetic and optical disks) using a sample of content from hybrid collection items dating from between 1980 and 2010. See Pennock, M., May, P., Day, M., Davies, K. and Whibley, S. (2016) ‘The Flashback Project: Rescuing disk-based content from the 1980s to the present day’, 11th International Digital Curation Conference, Amsterdam, Netherlands, 22-25 February. Available at:

  • The Library of Congress’s CD-R and DVD-R RW Longevity Research project page provides summarized outcomes and findings from several different complementary studies undertaken or are continuing. Library of Congress (n.d.) ‘CD-R and DVD-R RW Longevity Research’. Available at: [accessed 24 October 2023]

  • The Preserving Write-Once DVDs: Producing Disc Images, Extracting Content, and Addressing Flaws and Errors analytic report by George Blood Audio Video Film (GBAVF) in which, The report was one product of a contract with the company, in which they converted a set of write-once DVDs for the Library of Congress. The report describes the issues encountered and provides some detail about methods for carrying out the work,, offering an overview of the range and extent of the issues, as well as describing the corrective tools and processes that were used. See George Blood Audio Video Film. (2014) ‘Preserving Write-Once DVDs: Producing Disc Images, Extracting Content, and Addressing Flaws and Errors, Final Draft Report’. Available at [accessed 24 October 2023]

See also:

Scroll to top