I inherited this system and they had cron job which uses pg_dump for back up. I recently used to rsync to bring back my hot standby when it was out of sync and offline for few days because of space issue. That is when the thought that I might be able to use rsync to clone database.
Ah, I see. Yes, you can't use pg_dump to seed a standby, so if really want to have a pg_dump for backup, then you will need to have two different methods.
If I understood your reply correctly, you are currently using rsync for both clone and backup. Is that correct?
No, I use pg_basebackup and wal archiving/recovery for both backup, and for cloning dev/test servers. I'm pondering whether I should also take pg_dump occasionally so that I have a platform-independent secondary backup.
But I'm a big fan of practicing your restoration procedure, so if you want to keep using pg_dump as your backup, I think I'd also use that dump to make clones, unless there is a good reason not to.