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.

Group: Portable Media

Trend in 2021:

Consensus Decision

Added to List: 2019

No change No Change

Previous classification: Critically Endangered


Trend in 2022:


No change No Change


Imminence of Action

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

Significance of Loss

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

Effort to Preserve

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


CDs, laser disc 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

2021 Jury 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 over-sold. 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.

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.

Highly dependent on who is looking after the portable media but made more difficult over time. There is a lack of granularity in the definition of media types, so generic advice like ‘make sure you're moving your data to new forms of storage every 5 -10 years’.

Early generations of this media are not as robust as the current generation and can deteriorate significantly if not stored appropriately.

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