Where might I find the advice?
I set my Database Volume and Folder in OMV's PLEX setup to be: /srv/store/plexmediaserver/, yet PLEX stores nearly 20GB onto my boot USB in less than a week.
There seems to be too much here regarding PLEX that my searching ability falls short.
Thanks for your help.
You can always attempt to make this change yourself manually as documented on the Plex.tv forums: