Deleting WAL archives and pg_xlog when there is not a shared drive

Hello everyone,

I am trying to implement a high-availability cluster using only two nodes, without any shared disk storage.

In my implementation, the primary database has continuous archiving set up to a directory residing on the second node, where the standby database is. Streaming replication is also established between the two. When failover occurs, the standby is promoted to primary, and will start its continuous archiving but now on a directory on the other (former primary) node.

Call the primary node N1 and the standby N2. When N1 fails and N2 is promoted, can I safely delete the archive logs stored on N2 (which were archived by N1 when it was primary?)? Also, when N1 is started but now it must become a standby, I run pg_start_backup() on N2, sync the data directories (except pg_xlog) then pg_stop_backup() on N2. Can I safely delete everything under pg_xlog in N1 BEFORE starting it since anyways they won't be used (what will be used instead is the archive directory on N1 which is being populated by N2)?

Please let me know if my explanation wasn't clear. Thanks a lot!

- Yamen Laliberté