The system catalogs located in the global directory but the global directory isnt so big(500K). As I mentioned, the base directory is huge and the directory 16400 is the biggest inside. I checked some big files inside the directory 16400 (which represents the commbit database) and for some there isnt an object that match and for some there are. So, How can I continue ?
pg_total_relation_size should have counted the toast tables, as well as the indexes, if memory serves.
What I'm wondering about is the system catalogs, which Mariel's query explicitly excluded. 180G would be awful darn large for those, but maybe there's a bloat problem somewhere.
Otherwise, try to identify the largest individual files in the database directory ...