...
Transaction Logs
Backups
OS
...
PGDATA
...
swap
...
system logging (/var/log)
...
PGDATA
...
To see how much space a server is currently using:
psql# select datname, pg_size_pretty(pg_database_size(datname)) from pg_database;
I do not have any data growth information.
But we know that street addresses do not change much in the city.
We do have one area of the application that (ab)uses audit tables - but I would be a little surprised if this became an issue.