disk, drive, disk drive: A physical data storage
device. Such as a hard
drive or solid-state drive. Usually requires the use of a filesystem
to be useful. mergerfs does not deal with disks.
filesystem: Lowlevel software which provides a way to organize data
and provide access to said data in a standard way. A filesystem is a
higher level abstraction that may or may not be stored on a
disk. mergerfs deals exclusively with filesystems.
path: A location within a filesystem. mergerfs can work with any
path within a filesystem and not simply the root.
branch: A base path used in a mergerfs pool. mergerfs can
accomidate multiple paths pointing to the same filesystem.
pool: The mergerfs mount. The union of the branches. The instance
of mergerfs. You can mount multiple mergerfs pools. Even with the
same branches.
relative path: The path in the pool relative to the branch and
mount. foo/bar is the relative path of mergerfs mount
/mnt/mergerfs/foo/bar.
function: A filesystem call such as open, unlink, create,
getattr, rmdir, etc. The requests your software make to the
filesystem.
category: A collection of functions based on basic behavior
(action, create, search).
policy: The algorithm used to select a file or files when
performing a function.
path preservation: Aspect of some policies which includes checking
the path for which a file would be created.
out-of-band:
out-of-band in our
context refers to interacting with the underlying filesystem
directly instead of going through mergerfs (or NFS or Samba).