Stanford Digital Repository

What is the Stanford Digital Repository (SDR)?
The SDR is a set of services provided by SULAIR/DLSS to support Stanford's institutional stewardship of information in digital form. The SDR services focus specifically on maintaining integrity, authenticity, and readability of digital information over time; they provide a trusted environment for long-term digital information storage and preservation activities. The SDR is one of several SULAIR initiatives focusing on Digital Preservation.

In simpler terms, the SDR is a type of digital archive for trusted long-term digital information preservation.

Trust over time
The most important function of any long-term service ((partner)) is building and nurturing trust'maintaining the trust of depositors ((information stewards?)) is the SDR's foremost priority. The SDR's approach emphasizes three key, symbiotic principles: Security, Transparency, and Proof.

Security
Security of access is maintained and enforced by the SDR. The owner or custodian of deposited data decides who, under what circumstances, is entitled to a copy of their data from the SDR. Security of digital information is also maintained by the SDR. Information is encoded and stored in durable logical packages designed to prevent undetectable degradation or corruption, and current best practices are employed to all but eliminate the risk of unrecoverable corruption or loss. The SDR's design and operations are optimized to support this security mission. For example, all information is stored redundantly across different types of storage at different geographic locations. Also, the network of systems trusted to store information is available only to SDR staff'it is not directly connected to the Internet.

Transparency
All of the SDR's methods, processes, technology, business mechanisms, and public statistics are available upon request to all depositors, members of the Stanford community, and members of the Digital Preservation community for review and auditing. The SDR reports regularly to these communities as well with current statistics on preservation activity, data recovery events, and business viability. Depositors, however, retain control over the dissemination of statistics tied specifically to their deposited data.

Proof
When a copy of deposited information is requested from and delivered by the SDR, the SDR provides proof that the copy contains exactly the same information as originally deposited. While the SDR's technology and business mechanisms maintain the security and integrity of deposited information, providing proof on delivery actually demonstrates successful preservation. Proof provides the ongoing assurance necessary for long-term trust.

An Archival Environment, not a Delivery Environment
SDR services are designed for archival storage of information. They are tailored for periodic deposit and infrequent (i.e., neither daily nor weekly) delivery. The services do not constitute an efficient high-traffic delivery environment and should not be considered as a platform for daily end-user access. They are optimized for trust, not speed.

Currently available services
There is one service currently available: Bit-Preservation'. The SDR's bit-preservation service commits to stewarding ((preserving?)) digital files (aka 'bitstreams') and their metadata from any computer environment, ensuring the ability to deliver those files and metadata in current computing environments. For example, imagine storing files from an old AppleII computer, and being able to deliver those files in current environments such as Windows, Macintosh, Linux, and UNIX (and eventually other environments as they are developed and adopted).

Though bit-preservation for the long term can be quite valuable and is not a trivial activity, it does not ensure that files are easily usable in current environments. For instance, if a file from an old AppleII originally encoded an image, bit-preservation services can preserve and deliver that file to current environments but do not ensure that the current environment can render the file into an image. Additional services are required to preserve the originally intended usability of information encoded within digital files.

SDR bit-preservation service is currently available only via DLSS/DPG project management services. A signed contract is required for SDR services.

Services available soon
SDR services are being developed and tested to preserve information encoded within digital files. Specifically, digital image, text, and audio preservation will soon be available. These services will ensure that specific kinds of information encoded in digital files remain usable over time, and in many cases will be available for existing bit-preserved content without redeposit. The SDR is also developing preservation services for compound digital information types. The initial offering will preserve digitized books, which typically consist of images, text, structure, and behavior (page-turning).

More Information
For more information, please contact Keith Johnson, SDR Product Manager, at keithj@stanford.edu or (650) 804-1177.