Why not use cascading replication for this? That's precisely what I'm doing.
We need a "last chance" offsite backup of our backup server. Since the backup server isn't accessed by customers, we have the luxury of being able to shut it off briefly once per day. Call server "A" the backup, server "B" is offsite backup-of-backup: The procedure I'd like to implement is:
server B is always "cold" (Postgres not running)
while A is running, rsync A --> B
stop Postgres on A
rsync A --> B
restart Postgres on A
My question is: what about the WAL files? Do I need to rsync them from A to B too, or can/should I just clean out B's WAL directory, or something else?