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Why is it called "CLOCKSS"?

CLOCKSS, or Controlled LOCKSS (for Lots of Copies Keep Stuff Safe), runs on LOCKSS technology, but unlike LOCKSS (an open network), CLOCKSS is a closed system. There are only 12 nodes in the CLOCKSS network.

Why join CLOCKSS?

Libraries are joining CLOCKSS to ensure the world's e-content is protected for future generations of researchers.

Publishers are joining CLOCKSS to preserve their titles in a secure dark archive without the cost-prohibitive expense of building their own preservation and storage system. The CLOCKSS Board deemed that when a publisher's content is triggered (see what constitutes a trigger event below), CLOCKSS should not charge libraries for access; instead, the triggered content is made available for free at CLOCKSS' host sites.

Who is eligible to participate in CLOCKSS?

Any research library or publisher, worldwide.

Why is CLOCKSS considered the most cost-effective archiving solution?

CLOCKSS leverages existing infrastructure

CLOCKSS Archive Nodes -- libraries selected to be the custodians of the archived content -- are housed at institutions that have existed for decades, if not centuries. CLOCKSS supports the library's role in society as a "custodian of culture." These 12 institutions are located in geographically, politically, and geologically disparate locations in North America, Europe, and Asia-Pacific.

CLOCKSS runs on proven digital preservation technology

LOCKSS technology has been safely and securely preserving web-published content for over 10 years and has evolved with web advances to preserve new e-formats and genres.

What distinguishes CLOCKSS' from other dark archive solutions?

Business Model

Annual fees for publishers and libraries are set for a five-year period and designed to support operations during which time the Board will work to raise an endowment. The fees are intended to decrease at the end of the five years.

The Board considers an endowment critical to help cover costs. When times are tough digital preservation will not be a priority. An endowment will mitigate the risk to content preservation during economic downturns.

CLOCKSS is not a lease or a subscription service.


Publishers and librarians have equal say to influence CLOCKSS policies, priorities, and decisions that will impact them the most.

CLOCKSS participants have the opportunity to be deeply involved in all aspects of our industry and help to keep the community’s best interests at the forefront.


The CLOCKSS Board has two goals related to sustainability:

  • Minimize fees, and implement a win-win pricing model for publishers and libraries alike. Money spent on digital archiving competes with other needs. Minimize publishers’ fees; publishers pass along costs to libraries. Minimize libraries’ fees; leave libraries with more money to spend with publishers.
  • Make triggered content freely available. Do not set up another subscription layer that keeps the content behind yet ever-widening access barriers.

CLOCKSS incorporates into its business model an endowment to be raised over a five-year period, which is expected to underwrite 80% of ongoing costs.

Minimum yearly costs are projected to be low enough to make it possible to raise an endowment to cover enough of these costs to keep CLOCKSS preserving materials during hard times.


Both source files or presentation files are accepted for ingest and reservation.

CLOCKSS preserves the original files. When content is triggered from the Archive, the content is branded as the publisher's content.

Trigger Events

Triggered content will be made freely available to everyone. Other dark archives release triggered content only to their subscribers. This amounts to libraries paying publishers to subscribe to the e-content and paying a service to subscribe to the same e-content in perpetuity.

We're already participating in an archiving service. Why should we join CLOCKSS?

There are many reasons to join CLOCKSS, even if your institution already subscribes to an archiving service such as Portico.

Low cost

CLOCKSS runs on proven yet low-cost, open source LOCKSS software. Participation in CLOCKSS costs as little as $450 for libraries and $1,000 for publishers.

Mitigates Risk

In any market, it is important to have a choice of solutions. Those institutions that can afford to prefer not to keep all their digital preservation "eggs" in one basket.


CLOCKSS is a not-for-profit, joint venture developed by libraries and publishers. Unlike other archiving solutions, CLOCKSS answers to its community, not a parent company. Libraries and publishers have built their own archive and get to participate in its management.

When is a trigger event deemed to have occurred?

Trigger events include situations of non-availability of archived content in which:

Publisher No Longer in Business

The publisher is no longer in business or is no longer in the business of publishing content or providing access to previously published content and there are no successor interests or reversions or transfers of rights;

Title No Longer Offered

The publisher has stopped publishing and is no longer providing access to the content and there are no successor interests or reversion or transfer of rights;

Back Issues No Longer Available

The publisher has stopped offering or providing access to some or all of the back issues of the content and there are no successor interests or reversion or transfer of rights; or

Catastrophic Failure

While still publishing content, the publisher is not able to provide access to the content electronically due to technical or similar catastrophic and permanent failure.

Who gets access to content impacted by a trigger event?

Everyone. The materials are moved to a hosting platform and made available to everyone for free.

What does content preserved in CLOCKSS look like?

Take a look