DB2 Version 9.7 for Linux, UNIX, and Windows

Fast communications manager (Linux® and UNIX®)

For multiple partition instances, each database partition server has one FCM sender daemon and one FCM receiver daemon to provide communications between database partition servers to handle agent requests and to deliver message buffers. The FCM daemon is started when you start the multiple partition instance.

If communications fail between database partition servers or if they re-establish communications, the FCM daemons update information. You can query this information with the database system monitor. The FCM daemons also trigger the appropriate action. An example of an appropriate action is the rollback of an affected transaction. You can use the database system monitor to help you set the FCM configuration parameters.

You can specify the number of FCM message buffers with the fcm_num_buffers database manager configuration parameter. You can also specify the number of FCM channels with the fcm_num_channels database manager configuration parameter. The fcm_num_buffers and fcm_num_channels database manager configuration parameters are set to AUTOMATIC as the default value. The FCM monitors resource usage when any of these parameters are set to automatic, and incrementally releases resources. It is recommended to leave these parameters set to AUTOMATIC.