rsync is pretty much the standard for syncing one drive/directory to another.
Basic usage would look something like:
Code:
rsync -aAHXv /path/to/mount/point/A/ /path/to/mount/point/B/
You can refer to the man page for the definition of those flags and the others available in rsync. The first time you run it, it will copy everything. From then on it will compare sizes and timestamps to determine if any of the source files have changed, and if so it will update them on the destination.
