the archive command is a cp command: 'test ! -f /bigpart/local/incoming/%f && cp %p /bigpart/local/incoming/%f && chmod a+rx /bigpart/local/incoming/%f'
Your primary and secondary instances/db clusters are on the same server?
No, two servers: the temp partition (/bigpart/local/incoming) is on the master and is shared via NFS to the standby (/mnt/db1_incoming_wals). On the standby server the partition is mounted in rw mode and the postgres user can read and write (and delete) on the partition (verified now).
I modified the command in the recovery.conf as follow, but no changes and no entry in the log file: archive_cleanup_command = '/usr/pgsql-9.3/bin/pg_archivecleanup /mnt/db1_incoming_wals %r 2>>/tmp/archive_cleanup.log'
Note that the cleanup will happen only after "earliest file that must be kept to allow a restore to be restartable" has been applied on secondary.
Can you run pg_start_backup() and pg_stop_backup() a few times and see if archives are getting cleaned or not?
Also share anything unusual that you notice in your database log files [on both the instances]
I will check again, but no logs I found about it, maybe I need to enable in postgres.conf some logs details.
Use these parameters and then restart your DB Server. (to be safe first stop the primary --> Then Stop the secondary --> Then start the secondary --> then Start the primary)