📒Journaling and Versioning

Unlike traditional filesystems which store state directly, BanyanFS represents its state using a signed and versioned journal of changes, and records the cryptographic signature of each edit to a filesystem. This provides history tracking, rollbacks, and branching and merging; and empowers users to maintain multiple iterations of a file or dataset over time while tracking who has made changes to ensure the security and integrity of their data.

Journal-as-State

While traditional filesystems use journals as an addition to the data store to ensure file consistency, in BanyanFS the journal is the data store. Specifically, BanyanFS uses operation-based conflict-free replicated data types (CRDTs) to represent state as a catalogue of changes on data which can be repeated or "replayed" to reproduce any filesystem state, past or present.

Versioning and Time Travel

As discussed in Content Addressing, filesystem data is represented by a CID, which is a hash of the data. In BanyanFS, since data is represented by the journal, the CID of a filesystem is also the CID of its journal. Combined with signed edits described in Encryption (technical), this means verifying a CID verifies the current state of the filesystem as well as all previous versions of that state. Moving to a previous state moves to a previous CID and thus version. History, rollbacks, and auditing are extensions of the same core functionality.