pg_xlog dir not getting swept

About a day ago, there seems to have been some trouble in the network of my database (postgresql 9.3).

I’m running my db with a streaming replication setup with wall shipping.

I sync wal logs to a mounted networkdrive using archive_command = 'rsync -a %p /mnt/wal_drive/wals/%f </dev/null’. Somehow this command was failing, leading to my pg_xlog dir building up (590Gb). I rebooted the server, and the archiving command seems to succeed now - however - After about an hour of running, the pg_xlog drive has not decreased in size - I would have expect that! I can see that lot’s of files get’s synced to the /mnt/wal_drive/wals dir, but somehow the pg_xlog dir is not swept (yet)? Will this happen automatically eventually, or do I need to do something manually?

PS. I found this blog post http://www.hivelogik.com/blog/?p=513, but I’m unsure if it’s necessary and if it can be dangerous?

Best