软件包：backuppc-rsync（3.1.3.0-4） [debports]
patched rsync for BackupPC version 4
rsync-bpc (as it is called upstream) is a patched variant of rsync that has been developed specifically for server-side use with BackupPC (https://github.com/backuppc/backuppc) version 4. It extends the normal rsync so that it understands BackupPC 4's internal data structures on disk and can directly write to it.
You do neither need to use nor to install this package manually. It is pulled in as dependency where needed.
It is also no problem to install it in parallel with the normal rsync as it does not install any binary in the common search path ($PATH), just in a dedicated directory under /usr/libexec/.
In terms of functionality it replaces the less performant Perl module File::RsyncP (package libfile-rsyncp-perl) which was used by BackupPC version 3 on the server side.