When the replication starts, the security appliance console on the active unit displays the message "Beginning configuration replication: Sending to mate," and, when it is complete, the security appliance displays the message "End Configuration Replication to mate." Within replication, commands entered on the active unit cannot replicate properly to the standby unit, and commands entered on the standby unit can be overwritten by the configuration that is replicated from the active unit. Do not enter commands on either unit in the failover pair within the configuration replication process. Dependent upon the size of the configuration, replication can take from a few seconds to several minutes.
http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_configuration_example09186a00807dac5f.shtml#devi
