I'm running postgresql 9.3. I've currently got WAL archiving configured, but I'm doubting it's utility based on my configuration. On the master, I've got archive_command set to
rsync -az --ignore-existing %p postgres@slave_replica:/wal_archive
and on the slave replica, I've got restore_command set to
cp /wal_archive/%f %p || exit 0
If the slave server goes offline, it won't be able to receive the WAL files, and then when it comes back up, won't have what it needs.
Should I instead effectively reverse those two commands: archive the WALs locally on the master, and have slave replica rsync them from the master server? Or should I have the master archive the WALs both to a local directory and rsync them to the slave?