replication stops working

I have a 9.2 hot standby setup with replication via rsync. For the second time, it has stopped working with no apparent error on the primary or standby. Last time this happened I fixed it by restarting the primary. Yesterday I started a new base backup around noon and it replicated without any problems for about 12 hours. Then it just stopped and I don't see any errors in the Postgres log (primary or standby). I looked at other system logs and still don't see any problems.

I'm running Postgres 9.2.4 on CentOS 6.4. Thanks for any ideas or debug suggestions.

John DeSoi, Ph.D.

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wal_level = hot_standby
wal_keep_segments = 48
max_wal_senders = 2

archive_mode = on
archive_command = 'rsync --whole-file --ignore-existing --delete-after -a %p bak-postgres:/pgbackup/%f'
archive_timeout = 300