Lsyncd watches a local directory trees event monitor interface (inotify
or fsevents). It aggregates and combines events for a few seconds and then
spawns one (or more) process(es) to synchronize the changes. By default this
is rsync. Lsyncd is thus a light-weight live mirror solution that is
comparatively easy to install not requiring new filesystems or block devices
and does not hamper local filesystem performance.

Rsync+ssh is an advanced action configuration that uses a SSH to act file and
directory moves directly on the target instead of re-transmitting the move
destination over the wire.

Fine-grained customization can be achieved through the config file. Custom
actionconfigs can even be written from scratch in cascading layers ranging
from shellscripts to code written in the Lua language. This way simple,
powerful and flexible configurations can be achieved.