Hi Mike, here is the information from the CDR Analysis and Reporting Guide regarding the service parameters. Neither of which stipulate that a restart is necessary:-

Configuring CDR Service Parameters

CAR relies on the data in the CDR and CMR records to generate both the CAR and CDR reports. CAR requires that the CDR records be available in flat files on the CDR Repository node (the first node). To ensure that the CDR records are generated, and generated in the manner you can use for your particular system, you must enable certain Cisco Unified Communications Manager service parameters:

You can configure these parameters on the Service Parameters Configuration window in Cisco Unified Communications Manager Administration. To access the Service Parameters Configuration window, open Cisco Unified Communications Manager Administration and choose System -> Service Parameters. Choose the Advanced button to display the complete list of Service Parameters. The following list of service parameters can affect CDR/CMR records:

•System Parameters

-CDR Enabled Flag-This parameter determines whether CDRs are generated. Valid values specify True (CDRs are generated) or False (CDRs are not generated). For this required field, the default value specifies False. Enable this parameter on all servers in the cluster.

-CDR Log Calls With Zero Duration Flag-This parameter enables or disables the logging of CDRs for calls which were never connected or which lasted less than 1 second. Cisco Unified Communications Manager logs unsuccessful calls (calls that result in reorder, such as might occur because of a forwarding directive failure or calls that attempt to go through a busy trunk) regardless of this flag setting. This represents a required field. The default value specifies False.

•Clusterwide Parameters (Device - General)

-Call Diagnostics Enabled-This parameter determines whether the system generates call management records (CMRs), also called diagnostic records. Valid values specify Disabled (do not generate CMRs), Enabled Only When CDR Enabled Flag is True (generate CMRs only when the CDR Enabled Flag service parameter is set to True), or Enabled Regardless of CDR Enabled Flag (generates CMRs without regard to the setting in the CDR Enabled Flag service parameter). This represents a required field. The default value specifies Disabled.

Taken from this document:-

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/service/6_1_1/car/caranrpt.html#wpxref92733

If you click on the particular service parameter it displays the help and a description of the parameter. Generally it will tell you here if a reset is necessary when you change the parameter. I honestly cannot remember having to restart any service when I have enabled it in the past.

Hope this helps.

Allan.