We are using two slaves this way:
- Active server moves WAL files to local directory,
doesn't care about slaves
(basically archive_command = 'mv %p /some/arch_dir/%f')
- Slaves pull WAL files via rsync
- Slaves also do full syncs every several hours (pg_start_backup / rsync /
pg_stop_backup)
- Active server also has "cleanup daemon": removes redundant archived WALs
based on last full backup time
The slaves are not warm,
however they periodically create LVM snapshots and pg_dump databases.