Nimbus - A virtual, networked filesystem with strong upfront safety guarantees

The Nimbus Filesystem

Nimbus is a virtual, networked filesystem that provides upfront safety guarantees to a user, intended for personal use. In particular, it provides a filesystem that will FAIL LOUDLY and prompt the user if the consistency of reads and writes cannot be guaranteed. The user is thereby empowered to prevent conflicts before they occur.

Nimbus is implemented with FUSE and is currently a work-in-progress.

Modes of operation

Nimbus has two modes:

• development mode
• backup mode

Development mode

In development mode, when a project is being read/written to, nimbus will attempt to acquire a lock on the project. Development mode provides strong safety guarantees to the user. Intuitively, development mode enforces the notion that a user can only develop on one project/computer at a given moment. ¹ If a lock cannot be acquired it will FAIL LOUDLY and prompt the user for action (this should happen rarely). If a lock can be acquired, the user will not notice anything and everything will appear as normal. As nimbus will FAIL LOUDLY and prompt iff a lock cannot be acquired, the user is guaranteed that all successful read and writes are occuring on the most up-to-date version of the project and is consistent.

By default, projects will only be cached/stored on disk if:

• you are currently accessing the project
• the project has been recently accessed (and there is sufficient space to store the project)
• the project is pinned

Backup mode

In backup mode, eventual consistency is guaranteed. All operations are read-only. By default, if there is space, all projects will be cached/stored on disk.

Architecture

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