Plugin "hdclone"

Hi all,
I wrote a plugin (hdclone) which updates the Volumio library via rsync. The source library is located on two NAS hard drives while the Volumio library is located on two USB hard drives locally connected to a Raspi, that is where Volumio resides.
My problem is that while rsync is running, the mpd daemon starts its scan, so the whole process is slow and sometimes it hangs, because, I think, it tries to scan the partially transferred files.
A way of solving the problem could be to set the “auto_update” option in mpd.conf to “no” (also in “/volumio/app/plugins/music_service/mpd/mpd.conf.tmpl” ) start the rsync process and subsequently do an “mpc update”.
Unfortunately, this is not a good solution at least for these two reasons:
1) with every Volumio update, the mpd.conf file will return in its previous state;
2) with “auto_update” set to “no” it is not possible to use an external USB pendrive;
Finally, the solution should avoid a Volumio service restart, because the plugin is intended to be used when Volumio is playing music.
Any idea to solve this problem?