Endangered large

Materials saved to magnetic tape, portable hard disks or other magnetic media in the last five years where the reader devices are still supported and can be integrated easily into hardware infrastructure.

Group: Portable Media

Trend in 2021:

Consensus Decision

Added to List: 2019

reduced riskTrend towards reduced risk

Previous classification: Endangered


Trend in 2022:


No change No Change


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 many people and sectors.

Effort to Preserve

It would require a small effort to preserve materials in this group, with the deployment of proven tools or techniques.


LTO8 tapes; portable hard disks

‘Critically Endangered’ in the Presence of Aggravating Conditions

Poor storage conditions; encryption; digital rights management; lack of replication; lack of documentation; lack of periodic testing; lack of refreshment pathway; lack of access to readers; out of manufacturers’ warranty or no warranty; storage within paper files.

‘Vulnerable’ in the Presence of Good Practice

Regular review and testing; replication; refreshment plan; comprehensive documentation; high quality storage; regular maintenance of readers; multiple readers available.

2021 Jury Review

This entry was added in 2019 to ensure that the range of media storage is properly assessed and presented. Magnetic media is typically more fragile than optical media because it is susceptible to ‘bitrot’ and magnetic damage in ways that optical media are not.
However, the 2021 Jury commented on how the types of magnetic media used have improved the last five years, notably the use of LTO, increasing good practice and trending towards reduced risk in this respect. It is important to note that LTO tapes come in different generations. Some pose greater preservation risks now (e.g., an organization with no equipment or way of reading content), so the use of LTO is good practice so long as it includes the active management of associated risks.

Additional Comments

This entry is highly dependent on who is looking after the portable media but made more difficult over time. The lack of granularity in the definition means that only general advice can be offered, such as to refresh media. In time, it may yet be more useful to split all storage media (maybe 100 items long) with an indication of how long these can be expected to last. In many cases, specialists can recover obsolete media, but the cost of employing them can become an aggravating condition.

It is important to emphasize that the short lifetime of many storage devices is not a problem to be solved with new long-lasting storage technologies (and indeed, many inventions have come and gone). Cheap commodity storage has been purposely designed to deliver value at a low price for a short time. Therefore, management and preservation processes for monitoring and refreshment need to take these characteristics into account.

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