mirrordir mirrors filesystems over ftp or locally via a
minimal set of changes.
It is optimised for locally mirroring a device as an
alternative to RAID devices. It duplicates file-systems in
every detail, even correctly recreating hardlinks, devices
and access times. It works well mirroring ftp sites that
don't support ls-lR summaries. Mirrordir can take a C script
to customise the kind of files to mirror based on their stat
info, name, or other information.