Reap time is the number of seconds between each maintenance thread. By default, reap time is 180 seconds (3 minutes), which means that the maintenance thread will occur once every 3 minutes.
The maintenance thread will destroy connections to the database that have been inactive longer than the unused and/or aged timeout. For example, if the unused timeout is 1800 seconds, and a connection has been inactive longer than 1800 seconds, the maintenance thread will discard the connection until the minimum connections are reached. Similarly, if the aged timeout is 2000 seconds, connections that have been inactive longer than 2000 seconds will be discarded, regardless of the minumum connections value. Reap time can be disabled by setting the value to 0. You usually do not want to decrease the reap time value, as this will decrease the time between maintenance threads, which will put more traffic on the network.
Unused timeout will discard a connection when the current number of connections exceeds the minimum connection setting. In other words, if minimum connections is 10, and there are 5 current connections, the maintenance thread will not destroy the connections to the database when the unused timeout has been exceeded.
Aged timeout will discard a connection that exceeds the aged timeout, regardless of the minimum connections setting. One thing to take into consideration is that there may be other security devices in the network, such as a firewall, that will timeout stale connections. The aged timeout should be less than the firewall timeout, to ensure the firewall never detects an idle connection.