tahoe-lafs/docs/write_coordination.rst

Avoiding Write Collisions in Tahoe

Tahoe does not provide locking of mutable files and directories. If there is more than one simultaneous attempt to change a mutable file or directory, then an UncoordinatedWriteError may result. This might, in rare cases, cause the file or directory contents to be accidentally deleted. The user is expected to ensure that there is at most one outstanding write or update request for a given file or directory at a time. One convenient way to accomplish this is to make a different file or directory for each person or process that wants to write.

If mutable parts of a filesystem are accessed via sshfs, only a single sshfs mount should be used. There may be data loss if mutable files or directories are accessed via two sshfs mounts, or written both via sshfs and from other clients.