Currently, the BDR contains about 34TB of content. The storage layer is Fedora 3, and the data is stored internally by Fedora (instead of being stored externally). However, Fedora 3 is end-of-life. This means that we either maintain it ourselves, or migrate to something else. However, we don’t want to migrate 34TB, and then have to migrate it again if we change software again. We’d like to be able to change our software, without migrating all our data.
This is where the Oxford Common Filesystem Layout (OCFL) work is interesting. OCFL is an effort to define how repository objects should be laid out on the filesystem. OCFL is still very much a work-in-progress, but the “Need” section of the specification speaks directly to what I described above. If we set up our data using OCFL, hopefully we can upgrade and change our software as necessary without having to move all the data around.
Another benefit of the OCFL effort is that it’s work being done by people from multiple institutions, building on other work and experience in this area, to define a good, well-thought-out layout for repository objects.
Finally, using a common specification for the filesystem layout of our repository means that there’s a better chance that other software will understand how to interact with our files on disk. The more people using the same filesystem layout, the more potential collaborators and applications for implementing the OCFL specification – safely creating, updating, and serving out content for the repository.