Yesterday I moved my Plex installation from a Windows machine to a Linux machine. The primary data folders that needed to be copied over were Media, Metadata, Plug-ins, and Plug-in Support. It doesn't hurt to copy over some of the folders in Cache too. It's possible there may be some more data that needs to be moved over, but I don't have documented what.
After moving all the data, I updated the paths in the database for the new machine. Doing this allowed me to keep everything as it was and no new refreshes/scans needed to be done.
The location of the Plex modified SQLite for me was at /usr/lib/plexmediaserver/Plex SQLite. So the following is the bash commands to stop the plex server and open SQLite editor on Linux Mint 21.3.
service plexmediaserver stop
/usr/lib/plexmediaserver/Plex\ SQLite '/var/lib/plexmediaserver/Library/Application Support/Plex Media Server/Plug-in Support/Databases/com.plexapp.plugins.library.db'
And the following is the SQL I used to replace a D: drive with a path of /home/plex/drives/d/. You can replace these strings in the below code with your custom drives and paths.
#Replace backslashes with forward slash in paths
UPDATE media_parts SET file=REPLACE(file, '\', '/');
UPDATE section_locations SET root_path=REPLACE(root_path, '\', '/');
UPDATE media_streams SET url=REPLACE(url, '\', '/') WHERE url LIKE 'file://%';
#Replace root paths
UPDATE media_parts SET file=REPLACE(file, 'D:/', '/home/plex/drives/d/');
UPDATE section_locations SET root_path=REPLACE(root_path, 'D:/', '/home/plex/drives/d/');
UPDATE media_streams SET url=REPLACE(url, 'file://D:/', 'file:///home/plex/drives/d/') WHERE url LIKE 'file://%';
UPDATE media_streams SET url=REPLACE(url, 'file:///D:/', 'file:///home/plex/drives/d/') WHERE url LIKE 'file://%';
UPDATE metadata_items SET guid=REPLACE(guid, 'file:///D:/', 'file:///home/plex/drives/d/');
