Anti-goals

This document collects things that are explicitly not design goals for Bazil.

Trying to do these things would probably force us to trade off something we consider more desirable. For example, global locks would prevent weakly connected and offline operation, and thus there is nothing to be done there.

If you have an idea of how to gain some of these without trading off the unique and desirable aspects of Bazil, please do let us know!

Heavy transactional workloads

Don’t run your SQL database on top of Bazil. It’ll never be the best possible fit for that, both because of the userspace indirection and because of how Bazil stores its data.

Application-specific conflict resolution

Writing application and file format specific merging algorithms is an endless swamp. Bazil won’t prevent you from writing your own, and we’ll make it as easy as we can, but as a project we won’t spend effort on it.

Full POSIX compatibility

Cannot be done while supporting weakly connected operation.

For example, a rename of a file on one peer might not be immediately visible on another peer. The second peer might even happily write to the old file name. At some later time, the changes will be synchronized, in this case resulting in an update/delete conflict on the original file name.

We try to provide useful local operation semantics (for example, atomic renames), reasonable distributed semantics and always detect conflicts where they’ve occurred.

For simplicity, Bazil does not support hard links. This may never change, as behavior of hard links when synchronizing remote changes gets really murky.

$ ln foo bar    # not supported

mknod support

Bazil is a userspace filesystem, and what would these things even mean in a distributed context?

$ mknod foo b 12 34    # not supported

Immediate write visibility to other peers

We follow something closer to the AFS “commit-on-close”. File state becomes visible to peers only on fsync or close.

Current implementation even holds dirty file content fully in memory.

Global inode numbers across peers

The synchronization operates on filenames, not on inodes. Inodes are local to one peer.

Projects

Bazil is a distributed file system designed for single-person disconnected operation. It lets you share your files across all your computers, with or without cloud services.

FUSE is a programming library for writing file systems in userspace, in Go.