The pg_xlog partition start accumulating WALs and archive_status directory will shows .ready status when WAL partition gets 100% full or NFS is not available. Once pg_xlogs also fills to 100%, database will shutdown till the issue get resolved.
I have "archive_mode = on" in my configuration and wals are sent via NFS to another server.
Could you please explain what will happen if the partition where are wals kept gets full or the NFS server goes down ? Can it cause the database disfunction ?