Bertrand Drouvot looks at some new statistics that will be available in Postgres 18:
It means that, thanks to the new pg_stat_get_backend_io() function, we can see the I/O activity in each backend (in addition to the overall aggregate still available through the pg_stat_io view).
Click through for some examples of what you can see and how it works. This seems like it’d be pretty helpful in a clustering scenario to make sure that you’re getting the load balancing that you expect.