Cloud providers typically offers different geographical data centers, and during setup you can point ti any one of them. When you want to offer global access to WSI data then, you can have data stored in multiple zones.
The different instances of PMA.core in these zones can share a single database, yet the mounting points of the root directories can refer to different endpoints in different locales.
Any time the end-user requests a particular slide from a particular location, PMA.core automatically selects the storage location closest to the accessed node.
See also Instance settings.